American Kestrel Subspecies and Ids


The American Kestrel is a highly polytypic, and sometimes polymorphic, species of falcon present throughout the New World. The latest taxonomy suggests 17 different subspecies (Clements 2023), though some are probably synonyms. Due to a recent series of inquiries and rebukes, I am responding to these questions via this post, rather than give a lengthy explanation on each observation. Hopefully, I can perhaps clear the air on the taxonomy of this amazing little falcon, and help you be able to confidently identify them to subspecies.

Northern American Kestrel (ssp. sparverius)

-- Range: Throughout Alaska, Canada and the lower 48 States (except southeast), including northwestern Mexico. Will winter throughout Central America, as far as Panama. Occurs regularly in the Greater Antillean as well.

-- Id marks: The most variable of all subspecies, it is hard to quantify what precises falls under the "Northern" umbrella. Perhaps the most unique feature is the red crown spot. This feature is exclusive to the Northern, though not all individuals exhibit this red crown spot. In essence, the presence of a red crown spot absolutely confirms this subspecies, but the lack thereof does not mean it's another subspecies. Here's some photos, also note the variation in markings on the upper and underparts.

https://macaulaylibrary.org/asset/301274451 (no red crown spot)

https://macaulaylibrary.org/asset/394463281 (heavily reduced crown spot)

Tropical American Kestrel (ssp. tropicalis)

-- Range: Baja California to N

-- Taxonomic Issues: Looking at photos, I believe that peninsularis (Baja California) and nicaraguensis (Honduras and Nicaragua) likely represent synonyms of this race. They share may common traits and they don't seem to fall under the 75% rule (Amadon 1949) for diagnosable subspecies.

-- Id Marks: Compared to the very similar Northern Kestrel, this subspecies differs consistently in have much more cleanly white underparts in males (vs. tawny or buffy in US birds), limited barring to the upperparts, and always lacking the red crown spot. However, in wintertime, it may become very difficult to distinguish breeding Tropical Kestrels from blue-helmeted Northern Kestrels. Female diagnosis follows a similar scheme.



Southeastern American Kestrel (ssp. paulus)

-- Range: Breeds in certain pockets from South Carolina to central Florida, though some recapture banding records come from southern Florida and the Bahamas.

-- Id Marks: Very difficult to discern from Northern Kestrel, especially in winter when both subspecies overlap ranges completely. Males are generally described as being blue-headed (no red crown spot), reduced or absent underpart spotting, and limited barring on the upperparts. However, there's plenty of individuals that push the boundaries of these id traits, and it's likely due to some intergradation with Northern Kestrels in the Gulf states. Females are often credited with having thinner streaking below, not having quite the globous streaking of northern females. Mustaches are also thinner, making the face appear more whitish.



East Caribbean Kestrel

由使用者 birdwhisperer birdwhisperer2024年04月07日 04:19 所貼文 | 2 評論 | 留下評論


New Discovery: Three Undescribed Steiroxys species in One Locality in NE Oregon

On the afternoon of September 5th, I found what appears to be three undescribed Steiroxys species living at Penland Lake, Morrow County, Oregon. Twelve individuals were captured and photographed, and there was a variety of differing terminalia.

We documented 8 females that have subgenital plates consistent with that of species-z, an undescribed species with 2 iNat reports in Alberta and four genetic samples in GenBank (confirmed by one of iNat reports being a sample). This is the same species that is erroneously identified as trilineata on sources like SINA and GenBank. This species appears to be a parthenogenetic species, which would explain why we didn't capture a male. Here's links to the 8 reports.


I captured 3 (1 m, 2 f) individuals of a completely new species that I'm not calling species-l2. Male cerci are large, tubular and sharply hooked. The inner tooth is very close to the base, and not always clearly visible. Visully the cerci look most like species-k2 of Long Creek and Philips Lake, OR, but the outer tooth of k2 curves under the inner tooth, making the hook-like appendage appears mono-toothed. Female subgenital plate drastically different from any species I've encountered (approx. 13 undescribed species) with strong apical hooks but a distinctly hourglass-shaped plate. I'm hoping that I can convince the folks I'm working with to name this species clepsydra because of that unique feature.


Lastly, I found one more location species-g occurs. This is a wide-ranging species, and I have collected specimens in Morrow, Umatilla, Wallowa, Union, and Grant counties, though it almost certainly occurs in Baker County, and southeastern Washington.


由使用者 birdwhisperer birdwhisperer2023年09月09日 03:45 所貼文 | 1 評論 | 留下評論


Renew IPNRM for 2022?

@masonmaron @cgates326 @peterolsoy @the-catfinch @jnelson @uta_stansburiana @andybridges @philkahler @brodiecasstalbott @nightjar09 @kenchamberlain @benmeredyk @er-birds @peregrinetracy @sydnianajones @josegarrido @hkibak @rlfg @bwana28 @eliloftis @craigjhowe @docprt @danithedeer @flammulated @chrisleearm

If you are one of the mentioned people above, that means that between July and December since 2019, you are one of the top observers for "raptors" for Oregon and Washington counties east of the Cascade Mountains. All raptors observed within this time frame was automatically added to a project I managed called the Inland Pacific Northwest Raptor Migration. The idea was to observe all 35 expected species of raptors, starting from the breeders (July/August) to migrants (September/October), to wintering species (November/December). It was also supposed to document as many individuals as possible.

The reason why I'm tagging you is because I'm wondering if I should renew the project for the 2022 season. This August, I will be moving to Wyoming, which means I will personally have little participation in the project. I'm worried that if I do create the 2022 project, it will have a very low outcome of observations since a third of all the reports are my own: https://www.inaturalist.org/projects/inland-pnw-raptor-surveys?tab=observers

Now I understand some of you don't live within the project perimeters, all I'm searching for is public opinion on how the project went. If it is something you enjoyed and was looking forward to, then I'll get started on the 2022 project. If it was of minimum importance to you or you don't really care, then it's apparent a project for this year will just fizzle out. I just want to hear what you have to say.

由使用者 birdwhisperer birdwhisperer2022年06月07日 16:16 所貼文 | 3 評論 | 留下評論


Why the Bald Eagle has no subspecies

There are two recognized subspecies of Bald Eagle, the Northern Bald Eagle (Haliaeetus leucocephalus washingtoniensis) and the Southern Bald Eagle (H. l. leucocephalus). As many might know, I'm really into subspecies and I try to identify them whenever possible. But the taxonomy is not perfect and there's simply subspecies that do not exist. One of these is the Bald Eagle.

The problem stems from the fact that even the authors who do recognize the two populations only tentatively believe they exist. The two subspecies are differentiated purely by size and wing chord, with the largest birds, living in Alaska, having about a 244 cm wing chord, and the smallest birds in Florida, with a 168 cm wing chord. However, take these measurements with a grain of salt since there's quite a bit of sexual size dimorphism, with females possibly being 25% larger than the male. Now if you don't use the metric system, these measurements translate into 66-96 inches.

Now you might say, 30 inches is quite a size difference, surely you can identify a size difference between an eagle with a 5.5-foot wingspread from one with an 8 foot. Let's do some math here: If 66 inches is the smallest male leucoephalus and females can be as much as 25% larger, then we can see a female as large as 82 inches, which means the southern population can cover most of the size variation. Flip the coin and assume 96-inch eagles are the largest female washingtoniensis, then the smallest male can be 72 inches. That gives us quite a bit of size overlap.

Now that we've identified the root of the problem, how can you be sure that the "female" leucocephalus you're looking at is not a male washingtoniensis. And we haven't even touched clinal variation yet. We have evidence that the mass and wing chord of Bald Eagles gradually increases with the latitude. That means eagles nesting somewhere like Montana are going to be smaller than Alaskan eagles but larger than ones in Texas.

That makes making a distribution map quite difficult, because if size is gradually and consistently increasing throughout the country, then it's very difficult to draw a line and say, "eagles north of this line are washingtoniensis and those south are leucocephalus." In fact, that line I am speaking about is literally the 40th parallel. Using that logic, and using that invisible line to differentiate Bald Eagle subspecies, eagles you see in Nebraska are washingtoniensis, while those in Kansas are leucocephalus, even if there are two nests, only a few hundred yards away, separated only by a latitude and state line.

With the combination of no morphological differences, sexual size dimorphism, geographical clinal size variation, and the lack of a true distribution range all point to one thing. The Bald Eagle has no subspecies! This is why I am discouraging the use of such ids, because there is absolutely no way someone can photograph an eagle and claim it to be the northern subspecies, let alone expect an identifier to correctly confirm that sighting. That is my two cents worth.

由使用者 birdwhisperer birdwhisperer2022年04月17日 23:57 所貼文 | 1 評論 | 留下評論


The "Mangrove" Black Hawk

This is one of the most erroneously used avian taxon in all of iNaturalist, the Mangrove Black Hawk (Buteogallus [anthracinus] subtilis). Out of the 60 observations on iNat, most of them are likely not this subspecies.

The problem is, we don't really know what the Mangrove Black Hawk is. It was originally described as a species in 1905, with its distribution being the Pacific coastline of South America. Though many authors have voiced their opinions on the taxonomic status of the Mangrove Black Hawk, for simplicity reasons, I will gloss over those fine details. The real problem started in 1931 when Peters supported the speciation of the Mangrove Black Hawk but extended their range well northward on the Pacific slope, all the way to Chiapas, Mexico. That is a huge range expansion! Ever since, authors argued on the id marks of Mangrove and Common Black Hawk, and whether or not the two species bred sympatrically.

Bill Clark (2007) provided an excellent summary of the complex by saying in places like Costa Rica or Panama, the black hawks looked and sounded identical on both the Pacific and Atlantic slopes. His paper was later cited as the primary source for lumping the Mangrove Black Hawk with the Common Black Hawk in a SACC and NACC proposals. Both committees passed the lumping but kept the current erroneous ranges of the two subspecies.

My take on the issue is, reduce the range of the Mangrove Black Hawk back to what it was in 1905. The Mangrove Black Hawk, and I mean the real ones, are readily and reliable identifiable. There are 5 currently recognized subspecies of the Common Black Hawk, I say there's only two; nominate which resides from Arizona to Trinidad, and subtilis from Panama (possibly) to Peru. Here's some photos to compare to:

Arizona Common Black Hawk:

Ecuadorian Mangrove Black Hawk:

Costa Rican "Mangrove" Black Hawk (Pacific Slope):

Costa Rican Common Black Hawk (Atlantic Slope):

Now that you've taken a good look at hawks from both endpoints of their distributions, and a number of individuals in countries where both of supposedly present, what do you see? The Costa Rican "Mangrove" Black Hawks look nothing like the hawks in Ecuador. Those Costa Rican hawks look no different to those seen on the Atlantic slope, who look identical to hawks seen in Arizona. If we look into what Mangrove BH look like, and by that, I mean those with rufous secondaries, there seems to be a narrow contact zone. See here:

Southeastern Panama:

Pacific Slope of Colombia:

Note the distinct differences again? It seems as soon as you head into South America, suddenly, the hawks become a spitting image of what Mangrove BH are supposed to look like. Regardless of what you think, subspecies or species, that's your opinion. But for identification purposes on iNat, look for these 3 features in identifying:

  1. Rufous secondaries; both readily visible in flight and perched.
  2. Barred emarginated primaries, not dark.
  3. Mangrove BH probably does not occur north of Panama.
由使用者 birdwhisperer birdwhisperer2022年02月28日 05:57 所貼文 | 0 評論 | 留下評論


My 2021 Birding Year

Year Total: 305
Life List: 349

Best Month: May -- 178 species
Worst Month: February -- 93 species

State Stats -- State and Life

Oregon -- 283 year -- 304 life
Idaho -- 174 year -- 240 life
Washington -- 160 year -- 273 life
Utah -- 89 year -- 127 life
Montana -- 36 year -- 245 life

New Counties Visited:

Oregon -- Coos, Tillamook, Yamhill, Douglas, Clackamas
Idaho -- Bannock
Washington -- Okanogan, Skamania, Chelan
Utah -- David, Weber

Memorable Moments of 2020:
April 14 -- On a guided tour on private land, I got to see my life Sharp-tailed Grouse in Weiser, Idaho.
May 1 -- Found my life Neotropic Cormorant in the Bear River Migratory Bird Refuge, Utah.
June 1 -- Heard my life Mountain Quail in the Elkhorn Mountains, Oregon.
July 25 -- Found my life Red Phalarope at Mann Lake, Idaho.
August 11 -- Found my life Wandering Tattler at the La Grande Sewage Ponds, Oregon. First county record.
August 23 -- Found my life Green Heron at the Hood River Delta, Oregon.
August 23 -- Found my 2nd life Red Phalarope at the Hood River Delta, Oregon.
September 12 -- Found my life Great Crested Flycatcher at Montour Wildlife Management Area, Idaho
September 26 -- Found my 3rd life Red Phalarope at the La Grande Sewage Ponds, Oregon. This self-found rarity was a 2nd county report!
September 27 -- Found my life Little Gull in McNary National Wildlife Refuge, Washington.
October 4 -- Possibly heard my life Boreal Chickadee at Sherman Pass, Washington.
October 6 -- Found my life Ancient Murrelet at the La Grande Sewage Ponds, Oregon. First county record.
October 23 -- Found my life Emperor Goose in Beaverton, Oregon.
October 24 -- Found my life Northern Fulmar in Newport, Oregon. The storm surge might've cancelled my pelagic trip, but the storm brought the pelagic birds to shore.
October 24 -- Found my life Red-throated Loon and heard my life Wrentit at Seal Rocks and Ona Beach, Oregon. I unfortunately couldn't photograph or record either of them.
October 25 -- Found my life Rhinoceros Auklet in Klootchman State Park, Oregon.
October 25 -- Found my life Brown Booby in Coos Bay, Oregon.

由使用者 birdwhisperer birdwhisperer2022年01月01日 06:34 所貼文 | 0 評論 | 留下評論


My 2020 Birding Year

Year Total: 277 species
Life List: 342 species

Best Month: June -- 176 species
Worst Month: December -- 68 species

State Stats -- State and Life

Oregon -- 255 year -- 274 life
Idaho -- 180 year --- 220 life
Washington -- 138 year -- 274 life
Montana -- 41 year -- 247 life

New Counties Visited

Oregon -- Lincoln, Marion, Crook, Polk, Benton, Washington, Wheeler, Deschutes, Hood River and Jefferson
Idaho -- Twin Falls, Blaine, Gem, Camas, Bonneville, Owyhee, Butte, Madison, Bingham and Jefferson
Washington -- Douglas
Montana -- Mineral and Sanders

Year Lifers: Whimbrel, Black-and-white Warbler, Eastern Phoebe, Plumbeous Vireo, Cassia Crossbill, Broad-winged Hawk, Ruff, Magnolia Warbler, Black Oystercatcher, Snowy Plover, Wood Sandpiper and Acorn Woodpecker

Memorable Moments of 2020 Birding

January 6 -- Found continuing Black Scoter at the Tri-Cities Animal Shelter Pond. 1st county record. https://www.inaturalist.org/observations/37403989
January 18 -- While driving into town to run errands, I found both the first Oregon record of a Northern (abieticola) and Eastern (borealis) Red-tailed Hawk. These two subspecies are almost certainly underreported in the Columbia Basin and are likely annual. https://www.inaturalist.org/observations/37728667 and https://www.inaturalist.org/observations/37729458
February 18 -- Found three Snowy Owls at a known wintering grounds in northern Washington. https://www.inaturalist.org/observations/39307851
April 10 -- Performed my 2nd survey for Project WAfLS (Western Asio flammeus Landscape Survey) and got a pair of copulating Short-eared Owls.
April 23 -- Second times a charm to go to a lek and find 61 Greater Sage-Grouse and those were mostly males! https://www.inaturalist.org/observations/44556023
April 28 -- After two days of unsuccessful searching, I was finally about to get my life Whimbrel in northeastern Oregon. https://www.inaturalist.org/observations/44287770
June 1 -- Found a continuing Black-and-white Warbler at Malheur National Wildlife Refuge. Sighting unfortunately not accepted due to the lack of photos and the eBird reviewer being present who did not see it.
June 27 -- Found continuing Eastern Phoebe in Spokane, Washington; first county record. https://www.inaturalist.org/observations/51368685
July 18 -- Found life Plumbeous Vireo in Castle Rocks, Idaho, who liked my pishing. https://www.inaturalist.org/observations/54024122
July 19 -- Found life Cassia Crossbill in several places in the South Hills; confirmed by flight call recordings. https://www.inaturalist.org/observations/54127771
August 24 -- Found continuing Red-shouldered Hawk in Ladd Marsh, Oregon. 4th county record. https://www.inaturalist.org/observations/57653088
August 30 -- Finally got my first Spruce Grouse photos, three males in fact, in Wallowa County, Oregon. https://www.inaturalist.org/observations/58275181
August 30 -- Found life Broad-winged Hawk from probably two miles away on Ferguson Ridge in the Wallowa Mts. First northeastern Oregon record. Same individual (presumed by age, markings and Swainson's companion) was photographed by a good friend of mine the next day 50 miles away in the Powder Valley. https://www.inaturalist.org/observations/58122598 and https://macaulaylibrary.org/asset/259427941
September 1 -- Found continuing Ruff at near Cove, Oregon. https://www.inaturalist.org/observations/58253639
September 12 -- Found Magnolia Warbler at Thief Valley Reservoir, Oregon. Unfortunately, the warbler was incredibly secretive and since it was the first county sighting, the county reviewer told me it wouldn't be accepted without photos.
October 21 -- Found life Black Oystercatcher at Depoe Bay, Oregon. https://www.inaturalist.org/observations/63432501
October 22 -- Found life Snowy Plovers in Lincoln County, Oregon. Almost had the county high record with 41 individuals. https://www.inaturalist.org/observations/63497058
October 23 -- Found continuing Wood Sandpiper in Ankeny National Wildlife Refuge. 2nd Oregon record. https://www.inaturalist.org/observations/63541135
October 23 -- Found life Acorn Woodpecker in Klickitat County, Washington. https://www.inaturalist.org/observations/63544931
October 27 -- Found continuing Long-tailed Duck at the La Grande Sewage Ponds. https://www.inaturalist.org/observations/63891624
November 10 & December 6 -- Subspecies are important because I found a pair (yes, two) Eastern Song Sparrows at North Powder. They represent the 4th Oregon state record and 2nd Intermountain record. https://www.inaturalist.org/observations/64627927
November 16 -- According to eBird, my "best" photo of the year is a Black-capped Chickadee. https://www.inaturalist.org/photos/104957433
December 1 & 4 -- In a span of four days, I was able to find and photograph all 4 Blue Jays in Union County. https://www.inaturalist.org/observations/65987368 and https://www.inaturalist.org/observations/66232459
December 6 -- Finally found my biggest nemesis bird, the Harris's Sparrow at North Powder. https://www.inaturalist.org/observations/66237137

Goals for 2021
I do have a few goals I want to obtain in the following 12 months. Here's to name a few:

  • Obtained 8 new "photo lifers" so I can say I've photographed 300 species of wild birds.
  • See my life Eastern Bluebird because it's the most common bird on iNat I have not seen.
  • Photograph my next nemesis bird, the White-headed Woodpecker.
  • If safety permits, travel to Pennsylvania to bird for a week or two.
  • See 50 new state birds for Idaho so I can tie that number with OR and WA.
由使用者 birdwhisperer birdwhisperer2020年12月31日 19:21 所貼文 | 0 評論 | 留下評論


Steiroxys Revision Beginnings

Steiroxys is a genus of shieldback katydids with currently four described species. Though we know there are many undescribed species (Caudell 1907) and though it's sister genus Idiostatus was revised (Rentz 1973) with many new species, now much work has been done on this genus. All we know is, there are many species and most probably have small ranges. I've decided to tackle this issue and use citizen science to view distinguishing features of potential species. The downside to this, I cannot be able to revise the genus with just photos naturalists posted because in order to describe a species, you must have a holotype specimen. Which means I have to go out into the field, capture and ultimately kill the insect. I can send the specimen to a museum with my description of species and only then will the science community accept my work. Right now, this is just a outline of eight potential species photographed on iNaturalist and I will tag the observers as I go.

We have additional problems with this. Out of the four described species as of now, S. trilieatus and S. pallidpalpus holotype specimens are lost so we have no clue what they look like. To add onto the problems, I cannot get a sufficient view of holotype of S. borealis to determine the distinguishing features. As mentioned by Caudell, potential species can be identified by the male's cerci, the sensory organs on the abdomen end and the shape or size of it can determine species. For females, subgenital plate shape seems to play a role in identification but since no iNaturalist observer has photographed the female underside, they are all genus level for me. So here's the list:

Steiroxys species-a

Observer: @jimmylegs
Individuals: 2 males
Range: South-central valleys of British Columbia; Kamloops Lake to Kettle River Recreation Area.
Cerci: Probably incorrect terminology but the cerci have two "prongs". The two prongs in this potential species are close to the tip of the cerci and they curve sharply inward in unison.
Notes: A lot of confusion here for this. The cerci of James's individuals are identical to Steiroxys trilieatus photographed by Dan Johnson in the website "Katydids North of Mexico". What I need to decide is whether these are a described species or Dan misidentified and his individual is a part of species-a.


Steiroxys species-b

Observer: @justine_dm
Individuals: 1 male
Range: White Lake Grasslands Protected Area, British Columbia.
Cerci: Compared to species-a, the inner prong is thicker, shorted and triangular-shaped. The outer prong is straight and long.
Notes: Might not be a potential species since it's a nymph.


Steiroxys species-c

Observer: @geographerdave
Individuals: 3 males
Range: Mount Saint Helens, Washington
Cerci: Short and stubby. Inner prong curves slightly and the outer prong may bend outward. The indentation between the two prongs is indistinct.
Notes: If I were to name this species... Steiroxys helenae


Steiroxys species-d

Observer: geographerdave
Individuals: 1 male
Range: Cascades near Panther Creek Falls, Washington
Cerci: Short and stubby. Almost identical to species-c but the inner prong is straight, not curved and is almost equal length of outer prong.


Steiroxys species-e

Observer: @axyaliendragon
Individuals: 1 male
Range: Willamette National Forest near Rainbow, Oregon
Cerci: Intermediate between species-a and species-c. The prongs angle inward at a slight curve but not as distinctive as species-a. Inner prong has a more definitive prong.
Notes: I admit the cerci in the photos are kind of blurry so its possible it's not species. Could be S. strepens.


Steiroxys species-f

Observer: jimmylegs
Individuals: 2 males
Range: North Shasta Mountains, California
Cerci: Cerci enormous with the two prongs exceptionally curved and they'll meet in the middle.
Notes: This could be a new species but this part of California is within the proposed range limits of S. borealis. Unfortunately the provided photo on Orthoptera Species Files (OSF) regarding the holotype does not clearly show the cerci.


Steiroxys species-g

Observer: birdwhisperer (myself), @coreyjlange and @birdernaturalist
Individuals: 3 males
Range: Eastern Oregon
Cerci: Identical to species-a but the inner prong is placed near the base of the cerci not near the tip. This type of cerci shape occurs in three in the same general vicinity leaving me to believe it is indeed different from species-a.


Stieroxys species-h

Observer: Heidi (BugGuide user)
Individuals: 1 male
Range: Lucky Peak near Boise, Idaho
Cerci:: Similar to species-i, long, mostly straight prongs though the outer prong has a slight arch to it.


Steiroxys species-i

Observer: @maybedre
Individuals: 1 male
Range: Atla, Utah
Cerci: Short and straight, very similar to species-d but the outer prong is significantly longer than the inner.
Notes: This sighting is well within the proposed range of S. pallidpalpus but since the holotype specimen has been lost, I cannot confirm if the cerci are correct.

Summary: So there you go, 8 potential species. I hope with help of James, we can collect a few specimens and clear up the waters of this genus. I'm expecting quite a few more species to show up since we do not know which species live in Montana, Colorado, Idaho, eastern Washington and species limits throughout the Cascades. I wouldn't be surprised if the number doubles. Through citizen science, we can make plans on where to go to find species and that's what makes iNaturalist such a great platform for a project like this.

由使用者 birdwhisperer birdwhisperer2020年08月11日 23:08 所貼文 | 8 評論 | 留下評論


My Goals as a Biologists

I'm not quite a wildlife biologists, just a college freshman, but that doesn't mean I have goals. Here's a list of goals I want to acquire as a biologist.

  1. Confirm through vocalizations and plumage markers that the Song Sparrow subspecies merrilli range extends much further south than originally believed and the intergrade zone with montana is much larger than previously suspected.
  2. Redefine the plumage features of Song Sparrow subspecies montana and show how they are visually more similar to the nominate than coastal subspecies.
  3. Confirm through nuclei and mitochondria DNA testing that the Barbary Dove is a domesticated hybrid between the African and Eurasian Collared-Dove.
  4. Find and study nesting sites of Red-tailed Hawks in western Canada to confirm the validity of the subspecies abieticola and establish the percentage of intergradation with Harlan's Hawk.
  5. Do studies on vocalizations of Pacific Pseudacris and see if there's any evidence beyond mtDNA testing that the Pacific Tree Frog complex is indeed three separate species.
  6. Study breeding populations of Mexican and Central American Red-tailed Hawks to provide more accurate data on the distribution of subspecific population and show what features to use for identification.
  7. Provide a detailed guide on the distribution and identification of Orthoptera (Grasshoppers, Crickets or Katydids) in the Pacific Northwest through citizen science projects.
  8. Create a roadkill survey citizen science project to see what measures we can take to minimize deaths on the roads.
  9. Use GPS tracking to find wintering ranges of South American avian species, previously unknown such as the Antillean Nighthawk or Mexican martins.
  10. Explore the variation extend of the Bewick's and Whistling Swan and use yellow loral percentages to determine what can be called an intergrade.
由使用者 birdwhisperer birdwhisperer2020年05月12日 14:45 所貼文 | 2 評論 | 留下評論


Identifying Mexican and Central American Red-tailed Hawks

Recently, I've made several posts in regards to Red-tailed Hawks and it's subspecies. In my first journal post, "Identifying US and Canada Red-tailed Hawks", I explained in thorough detail the differences between Red-tailed Hawk subspecies in that area. I've had thoughts to do a similar post for countries not mentioned above as well and now I'm doing it. But also note that Mexican, Caribbean and Central American Red-tails are very ill-studied and future research may prove invalidity of subspecies or more depending on what researchers find. INaturalist is a great platform to find out the variety of the species so perhaps a little description of each subspecies may help users. All information used here is gathered from photos on iNat/ebird and research papers (usually the describing paper) in regards to the subspecies. Here we go!

Non-Migratory Caribbean Subspecies

The Red-tailed Hawk lives on nearly every island in the Greater Antillean and are vagrant to the Lesser Antillean (probably US migrants though). There are 2 subspecies.

Jamaican Red-tailed Hawk (Buteo jamaicensis jamaicensis)

Range: Jamaica, Hispaniola, Puerto Rico and norther Lesser Antillean Islands

Head: Normally rich brown with no markings. Throat is dark.

Upperparts: Same brown as head with blackish-brown mottling. White scapular mottling light.

Underparts: Bellyband variable from lightly to heavily-marked. Bellyband is normally blackish and often has barring. Rufous wash often occurs on the sides of the breast. Legs are typically unmarked. Breast and legs are white but can have a buff wash.

Wings: Patagials very thin and often has white markings encroaching on it.

Tail: Tail lacks tail banding and subterminal band is very thin. White uppertail coverts.

Morphs: Only light

Juvenile: Heavily marked below, white breast and considerable amount of white in the face.

Notes: Nominate subspecies, described in 1788. Comparing photos on iNat and eBird, I believe there's a good chance there might be geographic variation in the subspecies. I noticed individuals in Jamaica had very thin patagials and lightly to moderately marked bellybands. However, Hispaniola and Puerto Rico hawks, nearly every individual had incredible heavy bellybands, some where the entire belly was black. Patagials were also thicker and breast had rufous, not buff, tones. Subterminal band also appears broader in Puerto Rican individuals. I suspect some research needs to be done.

Photos: (1) Lightly-marked Jamaican Red-tailed Hawk -- Jamaican form (2) Moderately-marked, thick patagial Jamaican Red-tailed Hawk -- Hispaniola form (3) Heavily-marked, thick patagial Jamaican Red-tailed Hawk -- Puerto Rican form (4) Juvenile Jamaican Red-tailed Hawk -- Hispaniolan form


Cuban Red-tailed Hawk (B. j. solitudinis))

Range: Cuba, Bahamas and Isle of Pines.

Head: Quite variable. Most common head pattern is a rich brown unmarked head with dark throat but can have a darker malar or white throat. Some Bahama individuals have very pale, "washed out" heads.

Upperparts: Variable but is usually a shade darker than the head. White scapular mottling light to heavy depending on the darkness of the upperparts/head.

Underparts: Light to moderately-marked bellyband with rufous (Cuba) or white (Bahamas) breast. Rufous wash can occur on the sides of the breast. Rufous wash is usually present in the bellyband. Barring uncommon and does not occur on flanks.

Wings: Moderately prominent patagials, white unmarked underwing coverts.

Tail: Subterminal band moderately thick and red tail is usually lacks banding.

Morphs: Only light

Juvenile: Moderately to heavy bellybands with black markings on the sides of the breast making an incomplete breast band.

Notes: Appears to differ from jamaicensis by having thicker patagials, broader subterminal band and lighter bellybands. They are also darker dorsally and head coloring is more variable. Also keep in mind that Bahama individuals appear to be more variable than Cuban individuals and it may suggest geographical variantion but the variations are not nearly to the extent of jamaicensis on their islands.

Photos: (1) Heavily-marked, rufous-breasted Cuban Red-tailed Hawk -- Cuba form (2) Moderately-marked, rufous-breasted Cuban Red-tailed Hawk -- Cuba form (3) Pale-headed Cuban Red-tailed Hawk -- Bahamas form (4) Moderately-marked, bellyband washed Cuban Red-tailed Hawk -- Bahamas form (5) Heavily-marked, incomplete breast-banded juvenile Cuban Red-tailed Hawk -- Bahamas form


Non-Migratory Central American Subspecies

Central American hosts 7-8 different subspecies of Red-tailed Hawk and the variation between them is amazing. Also note that most non-migratory Central American subspecies are residents of the mountains and highlands. If you happen to see a Red-tailed in the lowlands, it's probably a migrant from the US.

Western Red-tailed Hawk (B. j. calurus)

Range: Resident and breeder to Baja California. Winter visitor throughout Mexico but recent evidence suggests that they migrate and winter all the way to Panama.

Head: Throat mostly dark, some have streaked, collared or white throats and these variations seem to occur more often in northern Canadian breeding areas or southwestern US deserts.

Upperparts: Very dark brown, white scapular mottling is light and barely visible comparative to other subspecies, however it is visible enough to use as an id feature to distinguish from other Buteo species.

Underparts: Perhaps the most variable subspecies in terms of underpart markings. Bellyband can vary from a few streaks and barring on the flanks to a thick black band across the belly with barring extending into the breast. Though typical bellybands have barring on the flanks and belly.

Wings: Almost all individuals have tawny or rufous underwings that contrast with the whit remiges. Patagials are dark and noticeably thick, making a huge "U" shape cut on the humerus region. If the bird is in wing, these two features are key to whether your Red-tailed is Western or not.

Tail: Incredibly variable from the "classic" all red-tail with thin subterminal band to a thickly banded tail with no distinct subterminal band. Also note where the wingtips end on the tail. Eastern/Northern Red-tails have wingtips barely extending past the uppertail coverts while calurus can extend from midway across the tail to the tail tips.

Morphs: Light, Rufous, Intermediate (only juveniles) and Dark. However light morphs dominate other morphs and from a compilation of photos I did for research about 96% of all calurus Red-tails are light morphs and 3% are rufous morphs.

Juvenile: Throat usually dark but younger individuals may have white throats that resemble borealis or abieticola. To distinguish light morphs from other subspecies, look for heavily marked bellyband and underwings. Only subspecies that have intermediate and dark morphs which is heavy markings on the breast (intermediate) or black underparts with white streaking, similar to Harlan's juveniles (dark).

Photos: (1) Dark-throated moderately-marked light morph calurus. (2) Tawny-breasted heavily-marked light morph calurus. (3) Lightly-marked calurus. (4) Dark morph juvenile calurus. (5) Heavily-marked rufous morph calurus. (6) Lightly-marked rufous morph calurus. (7) Flying molting very lightly-marked light morph calurus -- note thick patagials. (8) Flying typical light-morph calurus. (9) Flying dark morph calurus -- note that this was a breeder I observed all season and if you see something like this in the field and this is your only shot, best identify it as rufous/dark morph. (10) Dark morph calurus with very thick subterminal band.

Fuertes or Southwestern Red-tailed Hawk (B. j. fuertesi)

Range: Throughout northern Mexico with the range limits believing to be Durango and Tamaulipas.

Upperparts: Light to moderate whitish or buff scapular mottling.

Underparts: Very little to no bellyband and if markings do show, it's only two or three streaking marks. Western Mexican (aka Arizona) individuals appear to have more streaking (more being visually similar to a very lightly marked borealis) and even barring on rufous washed flanks.

Wings: Underwings completely white with the exception of thin but dark patagials and "chevrons" where the primary coverts end.

Tail: Tail is pale red with a thin subterminal band.

Morphs: Only light morphs.

Juvenile: Similar to borealis but with longer wings and bellyband has a distinct "V" shaped patterning where borealis is just streaking.

Notes: It is disputed if this is even a subspecies or just another form of borealis.

Photos: (1) Arizona fuertesi -- note slight rufous wash. (2) Arizona fuertesi on the far end of markings. (3) Flying Texas fuertesi on the far end of markings. (4) Flying Arizona fuertesi.


Sutton's Red-tailed Hawk (B. j. suttoni)

Range: Sierra de San Lazaro of Baja California

Head: Rich brown with dark throat or white throat.

Upperparts: Richly mottled upperparts with white scapular mottling light to moderate.

Underparts: Very little markings to the bellyband or can be absent overall. Typically has a rufous wash to the breast.

Wings: Dark, thick patagials with slight rufous wash to underwings.

Tail: Appears to be variable from brick red with very thin subterminal band to maroon with dense tail banding.

Morphs: Light and possibly dark.

Juvenile: Probably similar to calurus.

Notes: This is an incredibly understudied subspecies and perhaps not a subspecies. Neither iNaturalist nor eBird recognize the taxon but Avibase and Handbook of Birds of the World (HBW) however too. It is possible the subspecies is not well recognized because it was described by Dickerman (1993), quite some time after the American Ornithological Society (AOS) stopped doing assessments in their taxonomic updates. In a nutshell, the description of the subspecies was morphically intermediate between calurus and fuertesi, and measurably smaller. You can read what Dickerman said here -- https://www.jstor.org/stable/30054375?seq=1

Photos: (1) Possible Sutton's Red-tailed Hawk, note almost no bellyband. (2) Possible Sutton's Red-tailed Hawk, note rufous-washed breast. (3) Flying possible Sutton's Red-tailed Hawk.


Mexican Highlands Red-tailed Hawk (B. j. hadropus

Range: Varies by source. Presumed to be Mexican Highlands from Jalisco and Veracruz to Oaxaca. See notes.

Head: Rich rufous-brown with darker malar. White throat normally with collar.

Upperparts: Moderate to heavy white scapular mottling. Upperparts are a strong gray-brown.

Underparts: Light bellyband with dark teardrop-shaped streaking, though an absent bellyband (see notes) is not unusual. Flanks are very contrasting rufous compared to buff or white underparts.

Wings: Dark but thin patagials with rich buff underwings coverts. Banded remiges are well visible both dorsally and ventrally.

Tail: Variable in tail banding and color but it appears the main feature is, is that the 'subterminal band' is actually the tail tips with no visible red or white below the band.

Morphs: Light, rufous and dark. Differs from calurus rufous/dark morphs with white scapular mottling and black terminal band. See notes.

Juvenile: Unknown. See notes.

Notes: Incredibly understudied subspecies. The only published paper on the subspecies is the description paper (Storer 1962). He describes the range as being Jalisco to Oaxaca. Avibase and HBW claim the range goes to east coast of Veracurz. However no ebird photos of breeding Red-tails in hadropus purpose range show any of the features Storer claimed to be diagnostic. The individuals photographed in Jalisco, Guerrero and Socorro looked very much like kemsiesi or perhaps fuertesi. However a photo in Veracruz shows a Red-tailed that shows every feature Storer described in his paper and the features appeared to be consistent with all Veracruz and Puebla individuals. It is possible that hardropus is an eastern Mexican subspecies not western. However, a breeding dark morph individual was photographed in Guerrero and a rufous morph in Veracruz. Storer reported both hadropus and kemsiesi having dark morphs and we know fuertesi only occurs in light morph. So assuming that western Mexican Red-tails are not hadropus, it can be hypothesized that kemsiesi is not geographically separated by the Isthmus of Tehuantepec as originally believed and is the subspecies breeding from Jalisco to Nicaragua. Also in support of this hypothesis is the fact no hadropus individuals were photographed in western Mexico and vice versa for eastern Mexico. In southern Mexico, only one juvenile has been photographed in Puebla, subspecies undetermined but it may possibly be hadropus. The individual showed a heavy bellyband, dark throat, broader patagials and barred flanks. You can read Storer's paper here: https://sora.unm.edu/sites/default/files/journals/condor/v064n01/p0077-p0078.pdf

Photos: (1) Adult Veracruz Mexican Highlands Red-tailed Hawk that appears almost identical to Red-tailed Storer described. (2) Adult Veracruz rufous morph probably Mexican Highlands Red-tailed Hawk. (3) Adult Michoacán kemsiesi/hadropus Red-tailed Hawk. By range it should hadropus but it appears eerily similar to kemsiesi. Look up proceeding subspecies to compare photos. (4) Adult Michoacán dark morph kemsiesi/hadropus Red-tailed Hawk. Note tail tips is the subterminal band. (5) Colima kemsiesi/hadropus Red-tailed Hawk, note again the subterminal band. (6) Puebla juveniles kemsiesi/hadropus Red-tailed Hawk.


Kemsies Red-tailed Hawk (B. j. kemsiesi)

Warning! Theoretically, there is no "common name" for this subspecies but every other subspecies besides this one does and Kemsies is the Latin translation of the scientific name (Kemsies was a Yellowstone park ranger). I'm wondering if a better name can be applied such as the Sierra Madre Red-tailed Hawk to describe it's range.

Range: Chiapas, Mexico to northern Nicaragua. Though photographic evidence suggests that the Isthmus of Tehuantepec is a geographic "break" in their breeding range and they may live all the way up into Jalisco. See notes.

Head: Dark brown. Differs from other subspecies with dark auricular and cheek, not malar.

Upperparts: Light to moderate white scapular markings. Very dark charcoal-brown upperparts.

Underparts: Buff or white underparts with little or no bellyband. Whatever streaking they may have will be more prominent on the flanks. Belly can have a rufous wash that forms a "bellyband".

Wings: Patagials dark and moderately thick. Buff unmarked underwing coverts. Remiges are prominently banded both ventrally and dorsally.

Tail: Variable from brick red to pale chestnut-red. Subterminal band broad and prominent. Tail banding not uncommon. Uppertail coverts are whitish including bases to interior rectrices.

Morphs: Light, rufous and dark. See notes.

Juvenile: Variable, not studied hard so differences from other subspecies is uncertain.

Notes: Photograph evidence suggests that the subspecies range is not restricted the Nicaragua lowlands and the Isthmus of Tehuantepec and it may very well breed in western Mexico. Second issue about range is that most authorities claim kemsiesi range ends in Nicaragua but ebird reports that subspecies costaricensis is the expected subspecies for Honduras, El Salvador and Nicaragua and kemiesi being rare. However I cannot find any individuals photographed and identified as costaricensis appearing similar to "real" costaricensis in their breeding range in Costa Rica and Panama. Most of the reporting are probably misidentifications. They are variable in morphs and there appears to be quite a few rufous and dark morph breeders in their range. However it has been undetermined how dark morphs differ from hadropus. Dark morphs do differ from calurus with white scapular markings not buff or solid brown. Rufous morph differences are unknown as well. Juveniles are hard to place on subspecies especially when most juveniles photographed in the subspecies range are in spring, suggestable that some may not be resident birds. Further study is needed to determine differences.

Photos: (1) Adult Chiapas Kemsies Red-tailed Hawk -- textbook example. (2) Adult Guatemala Kemsies Red-tailed Hawk. (3) Adult Guatemala Kemsies Red-tailed Hawk. (4) Adult Honduras kemsiesi/costaricensis Red-tailed Hawk -- this bird was identified as costaricensis on ebird however I see no features supporting it. (5) Juvenile El Salvador kemsiesi/costaricensis Red-tailed Hawk


Costa Rican Red-tailed Hawk (B. j. costaricensis)

Range: Though all authorities (including the Clements Checklists) claim this subspecies range to be Costa Rica and western Panama, ebird reports having this subspecies being the expected subspecies throughout central America from Honduras and El Salvador to Panama, though it is expected that most if not all the sightings north of Costa Rica are actually kemsiesi.

Head: Solid rich brown-rufous. Collared throat, often with brown streaking on the white throat. Throat can be almost solid brown.

Upperparts: Light to almost no white scapular mottling. Very dark charcoal-brown upperparts with dark feather tips, giving a mottled appearance.

Underparts: Unique to the subspecies. White breast and very rufous-pink (like rotisserie chicken color, there I said it) belly. If a bellyband is present, it is lightly marked and the markings on the contrast line of the white breast and rufous belly.

Wings: Dark, thick patagials with rich rufous underwing coverts, identical in color with belly and in flight, makes the white breast more distinctive. Remiges are prominently banded.

Tail: Not quite as variable as other subspecies, seems to be relatively consistent for the tail to be between rotisserie chicken rufous to slightly redder but not quite the classic brick red. Tail normally has no subterminal band but a broken or thin subterminal band can be present in some individuals.

Morphs: Light

Juvenile: Like adults except throat is whiter. Bellyband can be heavy but the markings are pale. There is prominent streaking dribbling into the sides of the breast.

Notes: This is perhaps the most unique-looking subspecies in the entire Red-tailed spectrum.

Photos: (1) Adult Costa Rican Red-tailed Hawk. (2) Adult Costa Rican Red-tailed Hawk flying. (3) Rotisserie-colored Costa Rican Red-tailed Hawk. (4) Juvenile Costa Rican Red-tailed Hawk


Mexican Island Endemic Subspecies

There are two subspecies of Red-tailed Hawks that are endemic, meaning they live nowhere else, to offshore Pacific Islands in Mexico.

Tres Marias or Smoky-colored Red-tailed Hawk (B. j. fumosus)

Range: Tres Marias Island chain off the coast of Nayarit.

Head: Dark brown overall, including throat.

Upperparts: No scapular mottling. Dark brown upperparts the same color as the head.

Underparts: Dark brown-rufous mottled breast with rufous barring belly and flanks.

Wings: Dark, thick patagials with heavily marked underwing coverts.

Tail: Fairly consistent, rufous tail with thin or no subterminal band.

Morph: Rufous

Juvenile: Like adults except throat is white and collared and tail is finely banded.

Notes: Understudied subspecies as very few photos have been obtained (ebird has none). It may be possible that light or dark morphs exist but because of it's range isolation it is hard to obtain photos. To our current knowledge, only "rufous" morphs exist and is explanatory to the secondary name Smoky-colored Red-tailed Hawk.

Photos: (1) Adult Tres Marias Red-tailed Hawk. (2) Flying adult Tres Marias Red-tailed Hawk. (3) Juvenile Tres Marias Red-tailed Hawk.


Socorro Red-tailed Hawk (B. j. socorroensis)

Range: Socorro Island off the coast of Colima

Head: Solid brown, best described in my words as the discoloration in old milk chocolate.

Upperparts: Solid brown like the head with no scapular mottling.

Underparts: Bellyband lightly-marked with smoky-tawny underparts.

Wings: Unknown in rufous morphs. Dark morphs have solid dark underwing coverts.

Tail: Unmarked brick red tail with very broad subterminal band. Uppertail covert color unknown.

Morph: Light morphs (only juveniles), rufous and dark, though dark appears much more common.

Juvenile: Much more variation than adults. Intermediate morphs appear most common and have a arid dirt color with pale spotting on the marginal coverts. Light morphs are very heavily-marked with only a small patch of the breast white. Some appear to have very heavy upperpart spotting while others show scalloped marginal coverts.

Notes: Understudied subspecies and only photos of the subspecies occur on iNat. It's possible that light morph adults exist but range isolation and sensitivity limit a person's ability to study them.

Photos: (1) Adult dark morph Socorro Red-tailed Hawk. (2) Adult lightly-marked rufous morph Socorro Red-tailed Hawk. (3) Flying adult dark morph Socorro Red-tailed Hawk. (4) Juvenile intermediate morph Socorro Red-tailed Hawk. (5) Juvenile spotted Socorro Red-tailed Hawk


Migratory Subspecies

There are several subspecies that migrate into Mexico and Central America but do not breed in area. There are three migratory or wintering subspecies.

Eastern Red-tailed Hawk -- Buteo jamaicensis borealis

Range: Confirmed sightings includes several in Costa Rica, Tamaulipas, Quintana Roo and Cayman Islands, but probably migrates throughout Central America, eastern Mexico and Greater Antillean.

Head: White supercilium is common. Throat is usually white, streaked or collared; dark throat is rare. Malar/cheek region usually dark.

Upperparts: Scapulars are moderately to heavily mottled white.

Underparts: Lightly to moderately marked bellyband. Barring occurs often on the flanks, rarely anywhere else. Breast almost always white but tawny does occur.

Wings: No rufous on the underwings. Patagials are thin or dull. Limited underwing markings.

Tail: Nearly all individuals have white uppertail coverts. Subterminal band thin to moderate. Partial or incompletely tail banding is uncommon. Nearly all individuals have white tips to the tail.

Morphs: Only light.

Juvenile: Throat almost always white, supercilium often white, bellyband light to moderately-marked.

Photos -- (1) Clear-cut example of borealis. (2) Lightly-marked streak-throated borealis. (3) Clear-cut flying example of borealis. (4) Flying moderately-marked streak-throated borealis.


Krider's Hawk -- B. j. kriderii

Range: No confirmed reports in Mexico or Central America but there are many sightings along the Rio Grande in Texas, and water isn't hard to cross for hawks.

Head: Varies but is normally very whitish. Palest form has nearly completely white head. Darkest form has dark cheek and crown.

Upperparts: Heavy white scapular mottling and scalloping pattern is well defined on the rest of the upperparts.

Underparts: Little to no markings on the underparts and whatever markings an individual may have will be a few streaking. Underparts may have a buffy look, especially when compared side-by-side with the incredibly similar light morph Harlan's.

Wings: Patagials nearly none existent and thin with completely white underwing coverts. When compared to Harlan's look for buffy underparts, banded remiges and reddish-white tail with no other markings.

Tail: Variable with half of the tail being red to completely white. If the rectrices have a white base and reddish tail extends past half the tail, that's a solid candidate for Eastern X Krider's intergrade.

Morphs: Light only.

Juvenile: Heads are typically whiter than adults and white upperparts mottling is even more noticeable. Tail with whitish with banding.

Photos -- (1) Dark Krider's Hawk. (2) Lightest form Krider's. (3) Flying intermediately dark Krider's -- note buffy underwings. (4) Juvenile Krider's. (5) Flying juvenile Krider's.


Harlan's Hawk -- B. j. harlani

Range: Only two confirmed sightings in Mexico (Baja California Sur and Durango) but there are many sighting along the Rio Grande so it's easy to assume they winter in Tamaulipas.

Overall body difference: Besides I find Harlan's such a unique bird, I'm not going to go through all the body part features. All you need to know is; they are either black and white or cool brown and white, tail is incredibly variable from reddish mottled to brown mottling to white with reddish tip. Light morph adults can appear incredibly similar Krider's and are often misidentified in Western US but they differ with colder brown tones, white tail with mottled tail (usually in light morphs) and lack of buffy underwings. Harlan's also frequently show unbanded remiges and thicker patagials. Some Harlan's have Some juveniles can appear very calurus-looking but they differ with having "V" shaped tail banding.

Morphs: Around 84% are dark morph or intermediate morphs and the rest are light.

Photos -- (1) Light morph Harlan's. (2) White-spotted dark morph Harlan's. (3) Same dark morph Harlan's but shows awesome tail pattern. (4) Intermediate morph Harlan's. (5) Flying juvenile intermediate morph Harlan's. (6) Dark morph Harlan's.


Final Words and Overview

So there you go, all 15 Mexican, Central American or Caribbean Red-tailed Hawk subspecies. Most of endemic, non-migratory subspecies are poorly studied and as new information comes forth, we can better understand them. I believe iNaturalist is a great platform to find out this research and it appears we have a very strong Mexican community compared to ebird.

I believe that southwestern Mexico should be a place closely observed to see if it's true that Kemises' Red-tails really do reside there, along with Baja California Sur and see if the Sutton's Red-tailed really deserves subspecies status.

Also, another shoutout to all of those contributing their sightings and sharing their thoughts on subspecific ids. I hope this post will help you feel just a little more confident in identifying Red-tails.

Literature Sourced:

  • Clark, William S. (2014) -- Harlan's Hawk differs from Red-tailed Hawk, especially in plumages
  • Dickerman, Robert W. (1994) -- Undescribed Subspecies of Red-tailed Hawk from Baja California
  • Ligouri, Jerry (2004) -- Dark Red-tailed Hawks
  • Ligouri, Jerry and Brian L. Sullivan (2010) -- A Study of Krider's Red-tailed Hawk
  • Ligouri, Jerry and Brian L. Sullivan (2014) -- Comparison of Harlan's with Western and Eastern Red-tailed Hawks
  • Storer, Robert W. (1962) -- Variation in the Red-tailed Hawks of Southern Mexico and Central America
  • Wheeler, Brian K. (2018) -- Birds of Prey of the East
  • Wheeler, Brian K. (2018) -- Birds of Prey of the West

由使用者 birdwhisperer birdwhisperer2020年01月23日 17:46 所貼文 | 1 評論 | 留下評論