Thick or Large -billed Seed-Finch in Colombia (3 Viewers)

[Valéry Schollaert]

Hi all,

All males of big-billed Sporophila (former Oryzoborus) I've seen here were Thick-billed Seed-Finches. However, I've sometimes doubt of female-type individuals, including one I've published here already.

Large-billed Seed-Finch is not listed for Loma Merchán in e-Bird, thus I never really considered it, but I just realized the precise dots are not given because it is considered as a sensitive species...

I've seen one today, that looks larger than the ones I'm used to see, the beak is very big, but I'm not confident to distinguish both species I listed in the subject of the thread. Can some of you help me please ? How can I separate these two ? Is the coloured gape necessarily a sign of immaturity ?

Thanks

Edit : Loma Merchán is in Bucaramanga (Santander), the bird was taken at 1100 m asl.

 

[THE_FERN]

I don't know what the definitive answer to this is. However, large-billed usually has a clearly bulging culmen. It may have a more or less noticeable pale eye ring and it tends to be a warmer, slightly more rufous brown

The bird is definitely a young one with that gape. The dull colour and what we can see suggests thick billed to me. However, the angle isn't good for judging the culmen and there's a hint of an eye ring

 

[Valéry Schollaert]

Thank you @THE_FERN ! Here are other angles on the beak, can they help ?

 

[THE_FERN]

Thank you @THE_FERN ! Here are other angles on the beak, can they help ?

Compare with the "female" here:

ML614311214 - Large-billed Seed-Finch - Macaulay Library

Macaulay Library ML614311214; © Andres Vasquez Noboa; Sucumbíos, Ecuador

macaulaylibrary.org

(female in quotes because again we can see it's a young bird). Here's a roughly edited version comparing yours (centre) with theirs (left = large-billed, right = thick-billed)

(thick-billed image is: ML149097831 - Thick-billed Seed-Finch - Macaulay Library)

The bill of yours is closest to large-billed. The ground colour is closest to thick-billed and the eye ring is intermediate. From looking at other images I suggest: if the culmen is strongly arched it's large-billed. If not, if the lower bill is thin and pointed (no hint of convex shape, very acute angle at point) then it's clearly thick-billed. Ground colour can vary with wear and lighting. If very buffy then should be large-billed.

Yours looks a strong candidate for large-billed but I don't know if there's hybridisation and I don't know what range of bill shapes is. You need a Colombiano/a to comment.

 

[Valéry Schollaert]

Compare with the "female" here:

ML614311214 - Large-billed Seed-Finch - Macaulay Library

Macaulay Library ML614311214; © Andres Vasquez Noboa; Sucumbíos, Ecuador

macaulaylibrary.org

(female in quotes because again we can see it's a young bird). Here's a roughly edited version comparing yours (centre) with theirs (left = large-billed, right = thick-billed)

The bill of yours is closest to large-billed. The ground colour is closest to thick-billed and the eye ring is intermediate. From looking at other images I suggest: if the culmen is strongly arched it's large-billed. If not, if the lower bill is thin and pointed (no hint of convex shape, very acute angle at point) then it's clearly thick-billed. Ground colour can vary with wear and lighting. If very buffy then should be large-billed.

Yours looks a strong candidate for large-billed but I don't know if there's hybridisation and I don't know what range of bill shapes is. You need a Colombiano/a to comment.

I've seen a Thick-billed this morning, te beak is indeed more triangular, a bit smaller... I'll follow your advice and look for more opinion. It seems both are sympatric in this part of Colombia. Thank you.

 

[THE_FERN]

[Note the image I included got destroyed. I have recreated, added]

 

[THE_FERN]

I should also have noted that Opus has no images of large-billed seed-finch and only a male of thick-billed

 

[Valéry Schollaert]

I should also have noted that Opus has no images of large-billed seed-finch and only a male of thick-billed

Yes, I can add once the ID confirmed. I've 3 Colombian opinions, all in favour for S. crassirsotris, but with no justification.

 

[Valéry Schollaert]

The same individual came again, and I've seen it next to a Grey Seedeater. It is considerably larger, looked huge. This is, I guess, the final feature to confirm that is S. crassirostris, identification given also on the group "Red de Observadores de Aves en Latinoamérica " on Facebook.

I will add a photo on the opus and on e-Bird, as well in my Flickr in English and Spanish that have already near 70 close-up of birds of Loma Merchán.