Feathered Bipeds & Me.
Tuesday, January 17, 2006
Unidentified Aquila Eagle @ Hoskote
The new year started on a good note, with pretty awesome sightings of pelican flocks at YMC lake(on old madras road), and a sighting of a medium-sized aquila eagle at the fringes of hoskote lake, 23 kms north-east of Bangalore. This was on 1st Jan, 2006, a sunday.
The following exchange of thoughts & expressions by various people is not just about an identification of the Aquila eagle sighted, but it is also a perfect example of the difficulty that certain plumages of large raptors can pose in identification despite having procured good photographs.
Notes by Observers:Praveen.J, Job.K.Joseph & Prakash Poduval
Species in contention :-
Lesser Spotted Eagle: A. pomarina
Indian Spotted Eagle: A. hastata
Greater Spotted Eagle: A. clanga
Tawny Eagle: A. rapax
Steppe Eagle: A. nipalensis
As A.hastata is not described in any of the field books, descriptions of A.pomarina is taken as a bench mark for this species - though there will be slight plumage differences between these species, general characteristics might still be common.
From the Field
A moderate (not huge) raptor (A. hastata or A.rapax more than A.nipalensis) flew down over the Hoskote lake and landed on the grassy meadow (slushy?) next to the water line. Despite the size, our first implusive response was a Steppe Eagle because of the warm brown upper parts after ruling out Greater Spotted Eagle which has a comparatively shorter tail. Later when it took off, the distinct brown barring on the underwing and paler under parts suggested Tawny Eagle but once again the size and warm brown coloration in the upper wing took us towards Indian Spotted Eagle. In flight, the splayed fingers were kept higher than the wings. The tarsi appeared to be very lightly feathered, like an Indian Spotted Eagle.
Finer Analysis on the Images (The whole set of images are available in my yahoo album. The path is:-
http://photos.yahoo.com/jobkjoseph. The album is named "Indian Birds-Digital")
Facial Features:
Not a huge beak (A. hastata or A.rapax) but with a prominent gape extending well behind the eye (as in A.nipalensis). Nostrils appear oval (A.rapax or A.nipalensis), Iris appear dark (unlike A.rapax which is supposed to have yellow/light iris), throat appear greyish (A.nipalensis) but breast is dark and belly light-buff (as in A.rapax & quite unlike A.nipalensis). Head in general darker than belly.
Underside: All tail feathers finely barred from the half length of the tail to the tail-tip (seen when spread). 7 primaries, 7th primary very short & stunted (as in A. hastata) less than half (almost one third) of the length of 6th primary. 5th, 6th & 7th primary distinctly barred (much unlike A.hastata - more like A.rapax & A.nipalensis), 3rd & 4th indistinctly barred. Secondaries pale-cream with fine dark brown bars - dark bars thinner than the pale bands (unlike A. hastata). Base of the outer primaries unbarred pale-cream. Greater, Median and lesser coverts warm-brown - no distinct carpal crescents(unlike A.hastata). No dark trailing edge (unlike A.nipalensis). Tail length is almost as wide as the hand at the base of the wing & 3/4th the width of the wing at the carpal joint (rules out A.clanga). Hand long - wings angled at carpals. Legs appear to reach 3/4th the length of tail in flight - yellow legs.
Upperside: Nape - lighter than the head (A.nipalensis), secondaries dark with a fine white trailing edge. Greater coverts and primary covert dark - a thin white line separate the secondaries from greater coverts. Lesser and Median coverts warm brown, same as the back. A white wing panel seen in the primary coverts. White also in upper tail coverts but not in lower-back (unlike A.rapax). White blotches appear from above at the base of the wings. Tail from above all dark - same colour with secondaries.In short, the Aquila seems to be either A.rapax or A.nipalensis. Shape of the soft parts indicate A.nipalensis while the overall plumage and size indicate A.rapax.
REACTIONS(personal comments)
I would go for Tawny
Clement(Clement Francis)
(bngbirds)The photographs are wonderful.
I'd say it is Aquila nipalensis based on the long gapeline extending beyond the eye.
Regards,
Prashanth, Mysore
(Bird Forum)I think you are right with Steppe Eagle - maybe a 3rd/4th-year bird?
-Adam
(Bird Forum)I'm not sure this is a Steppe!...I reckon it's a Tawny Eagle.
The fine barring on the flight feathers, the lack of a dark trailing edge, and the pale window on the inner of the wing all point to it being a Tawny. A Steppe at this age would show a dark trailing edge to the wing and broader barring, plus it is very pale on the upperparts.
What do others think.
John. (John Barklay)
(Bird Forum)Actually, younger subadult Steppes don't show a dark trailing edge to the wings. In any event, the trailing edges on this bird appear quite worn.The upperwing flashes are very distinct on this individual. Are they so prominent on a Tawny?There are also the white patches on the back to consider, as well as the dark rump that contrasts greatly with the white uppertail-coverts.
-Adam
(India-nature-Pixs)Agreed that all plumage features point towards Steppe but for thesize and beak right? Have we totally eliminated the possibility of anhastata?I had made some notes from differrent sources ( I don't recollect itnow) on some positive ID features based on which hastata wasconclusively ID'ed in the past.
1. Head flatter than other aquilas.
2. Thick lips and large gape much like the steppe.
3. Stark contrast between the coverts and flight feathers on uppersideand underside.
4. Dark brown flight feathers and upper tail.
5. Moreover, as you note the size was much lesser than the steppe andit lacked baggy trousers as in the steppe.
6. The beak also looks very small for a steppe.
I also do not know whether how much we can rely on the carpalcrescents for IDing in differrent plumages.I am not suggesting this to be a hastata, but I think we better waitfor raptor experts to conclusively nail down the ID.
Regards,Chaitra
(bngbirds)Sorry for a delayed reply. Please look into A-R Handbook. The "old" A.rapax has a slit like nostril which is aligned perpendicular to the axis of the gape. The shape and orientation of the nostril is consistent character even used in the Keys to the Aquila eagles. Luckily you have one picture which clearly shows the bill and the nostril. Please confirm for yourself that it is not Aquila rapax.
In good faith,Krishna Mb.
At this point, it was realized that the observers made a mistake in comparing the eagle with A.pomarina. A.pomarina differs markedly from A.hastata.
1. Large gape extending well behind the eye
2. 5th, 6th & 7th primary distinctly barred
3. Dark bars thinner than the pale bands
These three features which were clearly seen in the photo are field ids for A.hastata
(pers comm)Its a Steppe Eagle.Rishad (Rishad Naoroji)
(pers comm)Certainly neither Steppe or Tawny. Round nostril means Greater or Indian Spotted.I would say latter on larger gape and plumage.
Bill Bill Harvey
(pers comm)We think it is an Indian Spotted Eagle in juvenile plumage because juvenile Steppe Eagles
- almost always show more white on the under greater coverts (although not always a continous white bar)
-also show a broad white trailing edge
- show under wing coverts which do not look darker than the remiges
- show broader dark bars on the secondaries and inner primaries
- usually show a unformly brown belly
- show a larger bill
- show broader pale tips to the greater coverts
- show a larger aquila patch
Antero & Annika (Antero Lindholm & Annika Forsten)
(OB)Great pictures!
I believe, that the eagle is Aquila hastata. I don't know much aboutrapax, but the bird is similar to the hastatas I've seen in Goa. Thevery pale inner primaries and the fine barring on the fligthfeathers fit hastata well (would be coarser in nipalensis and rapaxif I'm not mistaken). Hastata is actually (at least juveniles are)quite different than pomarina.The bird is in juvenile plumage. The plumage is uniform and there isa uniform pale trailing edge to the wings.A nipalensis of this age would have a broad whitish wing band on thegreater underwing coverts.
An example picture showing this feature:http://www.tarsiger.com/index.php?pic_id=JukkaJ1136621586&lang=eng
Examples of young hastatas, which show a similar upperwing: http://www.elisanet.fi/antero.lindholm/public_html/pedot/aquhas.htm
Those photos complement an article on Aquila hastata in the finnishbirding magazine Alula 2/2004. Yours:
Timo JanhonenHelsinki, Finland
(pers comm)I think that the pics are those of a sub-adult Steppe Eagle. The id is supported by the following points:
1. The extensive yellow gape flanges which reach the rear edge of the eye. The iris looks dark (black/brown); Tawny Eagle has yellow iris from sub-adult atage.
2. The distinct barrings on the tail and flight feathers
3. The upperwing pattern- white primary patches, white rump, thin white bar formed by the narrow white tips of the greater coverts, white patch on the lower back- is typical of the sub-adult Steppe Eagle.
4. Dark carpal area and pale wedge on the dark underwing formed by the pale inner primaries. But, the underwing pattern is a little confusing as it shows a sharp contrast between the dark underwing coverts and the pale flight feathers; probably, this effect could be formed by strong sunlight from above.
There is no dark trailing edge of wings; could be due to the worn plumage. Pale nape is not seen in any of the photographs. All the pics are of the same individual, I hope.I haven’t yet looked at the other picture. RegardsSashikumar (C. Sashikumar)
(pers comm)The photos are of a very pale juvenile Steppe Eagle. It is unusual as the wide white line on the underwing is not noticeable.Thanks for asking me.Do you know what camera equipment was used to take these photos?
Cheers, Bill Clark
The following exchange of thoughts & expressions by various people is not just about an identification of the Aquila eagle sighted, but it is also a perfect example of the difficulty that certain plumages of large raptors can pose in identification despite having procured good photographs.
Notes by Observers:Praveen.J, Job.K.Joseph & Prakash Poduval
Species in contention :-
Lesser Spotted Eagle: A. pomarina
Indian Spotted Eagle: A. hastata
Greater Spotted Eagle: A. clanga
Tawny Eagle: A. rapax
Steppe Eagle: A. nipalensis
As A.hastata is not described in any of the field books, descriptions of A.pomarina is taken as a bench mark for this species - though there will be slight plumage differences between these species, general characteristics might still be common.
From the Field
A moderate (not huge) raptor (A. hastata or A.rapax more than A.nipalensis) flew down over the Hoskote lake and landed on the grassy meadow (slushy?) next to the water line. Despite the size, our first implusive response was a Steppe Eagle because of the warm brown upper parts after ruling out Greater Spotted Eagle which has a comparatively shorter tail. Later when it took off, the distinct brown barring on the underwing and paler under parts suggested Tawny Eagle but once again the size and warm brown coloration in the upper wing took us towards Indian Spotted Eagle. In flight, the splayed fingers were kept higher than the wings. The tarsi appeared to be very lightly feathered, like an Indian Spotted Eagle.
Finer Analysis on the Images (The whole set of images are available in my yahoo album. The path is:-
http://photos.yahoo.com/jobkjoseph. The album is named "Indian Birds-Digital")
Facial Features:
Not a huge beak (A. hastata or A.rapax) but with a prominent gape extending well behind the eye (as in A.nipalensis). Nostrils appear oval (A.rapax or A.nipalensis), Iris appear dark (unlike A.rapax which is supposed to have yellow/light iris), throat appear greyish (A.nipalensis) but breast is dark and belly light-buff (as in A.rapax & quite unlike A.nipalensis). Head in general darker than belly.
Underside: All tail feathers finely barred from the half length of the tail to the tail-tip (seen when spread). 7 primaries, 7th primary very short & stunted (as in A. hastata) less than half (almost one third) of the length of 6th primary. 5th, 6th & 7th primary distinctly barred (much unlike A.hastata - more like A.rapax & A.nipalensis), 3rd & 4th indistinctly barred. Secondaries pale-cream with fine dark brown bars - dark bars thinner than the pale bands (unlike A. hastata). Base of the outer primaries unbarred pale-cream. Greater, Median and lesser coverts warm-brown - no distinct carpal crescents(unlike A.hastata). No dark trailing edge (unlike A.nipalensis). Tail length is almost as wide as the hand at the base of the wing & 3/4th the width of the wing at the carpal joint (rules out A.clanga). Hand long - wings angled at carpals. Legs appear to reach 3/4th the length of tail in flight - yellow legs.
Upperside: Nape - lighter than the head (A.nipalensis), secondaries dark with a fine white trailing edge. Greater coverts and primary covert dark - a thin white line separate the secondaries from greater coverts. Lesser and Median coverts warm brown, same as the back. A white wing panel seen in the primary coverts. White also in upper tail coverts but not in lower-back (unlike A.rapax). White blotches appear from above at the base of the wings. Tail from above all dark - same colour with secondaries.In short, the Aquila seems to be either A.rapax or A.nipalensis. Shape of the soft parts indicate A.nipalensis while the overall plumage and size indicate A.rapax.
REACTIONS(personal comments)
I would go for Tawny
Clement(Clement Francis)
(bngbirds)The photographs are wonderful.
I'd say it is Aquila nipalensis based on the long gapeline extending beyond the eye.
Regards,
Prashanth, Mysore
(Bird Forum)I think you are right with Steppe Eagle - maybe a 3rd/4th-year bird?
-Adam
(Bird Forum)I'm not sure this is a Steppe!...I reckon it's a Tawny Eagle.
The fine barring on the flight feathers, the lack of a dark trailing edge, and the pale window on the inner of the wing all point to it being a Tawny. A Steppe at this age would show a dark trailing edge to the wing and broader barring, plus it is very pale on the upperparts.
What do others think.
John. (John Barklay)
(Bird Forum)Actually, younger subadult Steppes don't show a dark trailing edge to the wings. In any event, the trailing edges on this bird appear quite worn.The upperwing flashes are very distinct on this individual. Are they so prominent on a Tawny?There are also the white patches on the back to consider, as well as the dark rump that contrasts greatly with the white uppertail-coverts.
-Adam
(India-nature-Pixs)Agreed that all plumage features point towards Steppe but for thesize and beak right? Have we totally eliminated the possibility of anhastata?I had made some notes from differrent sources ( I don't recollect itnow) on some positive ID features based on which hastata wasconclusively ID'ed in the past.
1. Head flatter than other aquilas.
2. Thick lips and large gape much like the steppe.
3. Stark contrast between the coverts and flight feathers on uppersideand underside.
4. Dark brown flight feathers and upper tail.
5. Moreover, as you note the size was much lesser than the steppe andit lacked baggy trousers as in the steppe.
6. The beak also looks very small for a steppe.
I also do not know whether how much we can rely on the carpalcrescents for IDing in differrent plumages.I am not suggesting this to be a hastata, but I think we better waitfor raptor experts to conclusively nail down the ID.
Regards,Chaitra
(bngbirds)Sorry for a delayed reply. Please look into A-R Handbook. The "old" A.rapax has a slit like nostril which is aligned perpendicular to the axis of the gape. The shape and orientation of the nostril is consistent character even used in the Keys to the Aquila eagles. Luckily you have one picture which clearly shows the bill and the nostril. Please confirm for yourself that it is not Aquila rapax.
In good faith,Krishna Mb.
At this point, it was realized that the observers made a mistake in comparing the eagle with A.pomarina. A.pomarina differs markedly from A.hastata.
1. Large gape extending well behind the eye
2. 5th, 6th & 7th primary distinctly barred
3. Dark bars thinner than the pale bands
These three features which were clearly seen in the photo are field ids for A.hastata
(pers comm)Its a Steppe Eagle.Rishad (Rishad Naoroji)
(pers comm)Certainly neither Steppe or Tawny. Round nostril means Greater or Indian Spotted.I would say latter on larger gape and plumage.
Bill Bill Harvey
(pers comm)We think it is an Indian Spotted Eagle in juvenile plumage because juvenile Steppe Eagles
- almost always show more white on the under greater coverts (although not always a continous white bar)
-also show a broad white trailing edge
- show under wing coverts which do not look darker than the remiges
- show broader dark bars on the secondaries and inner primaries
- usually show a unformly brown belly
- show a larger bill
- show broader pale tips to the greater coverts
- show a larger aquila patch
Antero & Annika (Antero Lindholm & Annika Forsten)
(OB)Great pictures!
I believe, that the eagle is Aquila hastata. I don't know much aboutrapax, but the bird is similar to the hastatas I've seen in Goa. Thevery pale inner primaries and the fine barring on the fligthfeathers fit hastata well (would be coarser in nipalensis and rapaxif I'm not mistaken). Hastata is actually (at least juveniles are)quite different than pomarina.The bird is in juvenile plumage. The plumage is uniform and there isa uniform pale trailing edge to the wings.A nipalensis of this age would have a broad whitish wing band on thegreater underwing coverts.
An example picture showing this feature:http://www.tarsiger.com/index.php?pic_id=JukkaJ1136621586&lang=eng
Examples of young hastatas, which show a similar upperwing: http://www.elisanet.fi/antero.lindholm/public_html/pedot/aquhas.htm
Those photos complement an article on Aquila hastata in the finnishbirding magazine Alula 2/2004. Yours:
Timo JanhonenHelsinki, Finland
(pers comm)I think that the pics are those of a sub-adult Steppe Eagle. The id is supported by the following points:
1. The extensive yellow gape flanges which reach the rear edge of the eye. The iris looks dark (black/brown); Tawny Eagle has yellow iris from sub-adult atage.
2. The distinct barrings on the tail and flight feathers
3. The upperwing pattern- white primary patches, white rump, thin white bar formed by the narrow white tips of the greater coverts, white patch on the lower back- is typical of the sub-adult Steppe Eagle.
4. Dark carpal area and pale wedge on the dark underwing formed by the pale inner primaries. But, the underwing pattern is a little confusing as it shows a sharp contrast between the dark underwing coverts and the pale flight feathers; probably, this effect could be formed by strong sunlight from above.
There is no dark trailing edge of wings; could be due to the worn plumage. Pale nape is not seen in any of the photographs. All the pics are of the same individual, I hope.I haven’t yet looked at the other picture. RegardsSashikumar (C. Sashikumar)
(pers comm)The photos are of a very pale juvenile Steppe Eagle. It is unusual as the wide white line on the underwing is not noticeable.Thanks for asking me.Do you know what camera equipment was used to take these photos?
Cheers, Bill Clark
So it's looking more like Indian Spotted? At least I thought it was the same species as Bill Clark!
-Adam
This Is definately NOT a Steppe Eagle! It seems to me that this is in fact an Indian Spotted Eagle, which is not really commom. These are some of the better shots I've seen of this species.
SeK
Looks confusingly like it has Steppe and Indian Spotted features first impression was Steppe on plumage but appears too lightly built for Steppe, esp bill etc? not familliar enough with ISE though... I knew we should have run that id piece on them in OBC Bulletin...
-Tim Allwood
I'm far from an expert on these birds, having never even been to India. Still, I think I have a relevant comment. Looking in some of my raptor books and the Ripley Guide to the Birds of South Asia, I noticed that there is a field mark that no one seems to have considered. It is the streaking of the underparts (or absence, thereof). Forgive me if someone made reference to this character, but I didn't notice it mentioned by anyone.
When dealing with raptors, I'm inclined to give more weight to structural features rather than minor variations in color. Color is simply too variable in these birds. So, based on gape length, I'm thinking it's either a juvenile hastata, or nipalensis. Gape length (among other things) causes me to rule out clanga, and rapax. Once narrowed to hastata or nipalensis, I am leaning strongly towards hastata due to the streaked underparts of the breast and belly. This particular color issue is not a matter of subtle degree. If my references are correct, nipalensis is never streaked below, in any plumage, but juvenile hastata always are. That is my understanding. The photos clearly show streaking below. Therefore, the bird would seem to be hastata.
--Kristin Williams
(In Litt.)When you have eliminated the impossible whatever remains, however improbable, is the truth
Sherlock Holmes
Moral of the story: With many observations ruling out tawny, steppe, & the greater spotted, the only other possibility to the ID is a sub-adult/immature indian spotted eagle.
