Aquile

Unidentified Aquila Eagle @ Hoskote

The following episode is not about an identification of an Aquila eagle, but it is am illustration of the difficultly certain plumages of large raptors can pose in identification despite having procured good photographs. (Photo Credits: Job.K.Joseph)

Notes by Observers:

Praveen.J, Job.K.Joseph & Prakash Poduval

In contention
Lesser Spotted Eagle: A. pomarania
Indian Spotted Eagle: A. hastata
Greater Spotted Eagle: A. clanga
Tawny Eagle: A. rapex
Steppe Eagle: A. nipalensis

As A.hastata is not described in any of the field books, descriptions of A.pomarania 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.rapex 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.

Finer Analysis on the Images

Facial Features: Not a huge beak (A. hastata or A.rapex) but with a prominent gape extending well behind the eye (as in A.nipalensis). Nostrils appear oval (A.rapex or A.nipalensis), Iris appear dark (unlike A.rapex which is supposed to have yellow/light iris), throat appear greyish (A.nipalensis) but breast is dark and belly light-buff (as in A.rapex & 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.rapex & 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.rapex). 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.rapex or A.nipalensis. Shape of the soft parts indicate A.nipalensis while the overall plumage and size indicate A.rapex.

REACTIONS

(pers comm)

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 the
size and beak right? Have we totally eliminated the possibility of an
hastata?

I had made some notes from differrent sources ( I don't recollect it
now) on some positive ID features based on which hastata was
conclusively 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 upperside
and underside.
4. Dark brown flight feathers and upper tail.
5. Moreover, as you note the size was much lesser than the steppe and
it 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 carpal
crescents for IDing in differrent plumages.

I am not suggesting this to be a hastata, but I think we better wait
for 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.pomarania. A.pomarania 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 about
rapax, but the bird is similar to the hastatas I've seen in Goa. The
very pale inner primaries and the fine barring on the fligth
feathers fit hastata well (would be coarser in nipalensis and rapax
if 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 is
a uniform pale trailing edge to the wings.

A nipalensis of this age would have a broad whitish wing band on the
greater 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 finnish
birding magazine Alula 2/2004.

Yours:

Timo Janhonen
Helsinki, 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.

Regards

Sashikumar (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

(In Litt.)

When you have eliminated the impossible whatever remains, however improbable, is the truth

Sherlock Holmes