Hard Tropical Hummers (Andean) (1 Viewer)

[Perakito]

I'm having trouble identifying several of the tropical hummingbirds that I saw (in the Andes of the Merida state of Venezuela)- and unfortunately for anyone who is going to try to help me, yes, it included Chlorostilbon... (emeralds).
The first two summers I neatly (abeit ignorantly) separated this hummer and that into species shown in the book, but upon closer observation this year (my first year there after having birded with experts a few times- Cornell Lab of Ornithology members ) I've found them to be much, much, much harder.
Red-rumps: I have seen several hummers which I at first thought were Blue-tailed Emerald (I thought the copper tinge on the rump was an effect of iridescence), Steely-vented Hummingbird, and Copper-rumped Hummingbird. Looking closer at the "Blue-tailed Emeralds" and "Steely-vented"s, I found that their bellies and breasts were actually a dusky, buff-like color that had heavy specklings of bluish and greenish scale-like feathers. Otherwise, most of them fit exactly the picture of Steely-vented in the Birds of Venezuela book- including the ends of the overtail coverts being blue, and the base being rusty-copper colored. Looking closer at the "Copper-rumps", they had all-white undertail coverts-and prominently puffy legs. I notice now that the rusty color does not extend all the way down the overtail coverts, making them basically the same as the "Blue-tails" and "Steely-venteds"- just with more of the copper color- yet sharing the weird bellies with the rest of them (I believe they are all one species, just with a confusingly diverse set of colorations- or iridescence-based color changing). (pictures will be included soon in gallery, if not attached)
The book is lacking in in-depth descriptions of the Steely-vented Hummingbird, which seems the most likely candidate for the pictures. If I could just get some confirmation on variation like this is Steely-vented Hummingbirds or Amazilia-type hummingbirds, that would be really great.

Hummer1 is a previously-thought Copper-rump-Amazilia tobaci
Hummer2 is a "Steely-vented Hummingbird"-Amazilia saucerrottei
Hummer3 was previously ID'd as "Blue-tailed Emerald"-Chlorostilbon mellisugus

 

[Perakito]

Chlorostilbon: Isn't that the hardest hummer genus?

Furthermore, I am not entirely certain of my ID of the local certainly-Chlorostilbon species. It's REALLY hard to get a good look at the tail- those guys move like lighting, and even when paused in midair, their tail flares out so fast it's a blur. Me and my father got some non-scoped pictures (using flash), but unfortunately, the tail still isnt easy to make out. I've included one for the tail, and one for wing-tail comparison- the two main ID keys I know about.
As for range separation, I came up with Narrow-tailed Emerald- but am uncertain. The city of Merida was within seeing distance- we were about 1840m above, on the edge of a valley, and looking down along the valley you could see the city. What shakes my decision most is the 1840 part- which is supposed to be right on the boundary between short-tailed and narrow-tailed.
I hope one of my details will help someone to help me ID it.

 

[Rasmus Boegh]

Actually, male Chlorostilbon are not that bad as long as you stay away from Colombia where a bunch of very similar Chlorostilbon/Lepidopyga/Amazilia (-group) occur together. In Venezuela the most similar species have different distributions with little or no overlap (the problem is of course, that Merida is one of those areas where two such species meet, although they tend to be found at different altitudes). Anyway, for some reason I am unable to see a large version of the photos posted in the second post, so I'll refrain from commenting on them. The fourth photo in the first post is the easiest: A Steely-vented (Amazilia/Saucerottia saucerrotei). With a bit of experiance actually fairly easy to separate from Copper-rumped (A./S. tobaci). From this angle notice the relatively limited amount of copper on the rump and the small blue feathers at the base of the tail (they are also coppery in most races of the Copper-rumped). As always be warned that the colours can look very different from different angles and that colour of the undertail coverts is far more reliable if you enter the range of A./S. tobaci monticola (regardless of subspecies Copper-rumped always has reddish to brownish undertail coverts, while the undertail coverts always are blue with greyish edging in Steely-vented). The first & second photo in your first post quite probably is a Steely-vented as well, but I'll refrain from saying anything for certain due to the quality of the photos (they're not exactly easy targets for a photographer - they're fast little birds!). Third photo could very well be yet another Steely-vented, but I'm not certain (I think the crissum appears to be dark blue with pale grey edging). If it hadn't been for altitude and the apparent lack of white tail tips I'd be very tempted by female White-chinned Sapphire (Hylocharis cyanus).

Anyway, a few things to note when dealing with the typical "Green Hummingbirds" from this group:

1) Size (this is especially useful when having to establish if it is a Chlorostilbon or a member of the Amazilia group).
2) Lenght of bill compared to head + if it appears completely straight or slightly curved (as in 1, this can be very useful for separating Chlorostilbon and members of the Amazilia group).
3) Exact tail shape. Is it rounded? Is it forked and if yes, how deeply?
4) Bill colour.
5) Colour of tail (notice that some species have a bicoloured tail, e.g. blue central rectrices, with outer rectrices green).
6) Colour of undertail coverts.
7) Colour of rump/lower back.
8) ... realize that many hummingbirds are just too fast and getting an ID of every single individual observed is completely impossible even for a pro.

 

[Perakito]

OK... I can tell you that in all the four pictures (the first three possibly being the same individual, even), they seemed to fit steely-vented pretty well, with the exception of the crissum and the varying degrees of rusty extension up from the overtail coverts. The one in the third picture, I got lots of pictures of- one day I found it probing an aloe, and then a bush that is called something like "rods of china"... I know it's from china, but a lot of gardens have it, and hummers seem to love it. It has a red disc, and then a tube coming from the center- about the length of the Rufous-tailed hummingbird. The hummer was going back and forth between those two, and then every minute or so, it would rest of the twigs- I can give you a pic of the rump if you want, but all of them are rather contrasty.
I also thought that they might be female White-chinned Sapphires, but like you said, the lack of white tips, and the range, and the apparant lack of any males whatsoever (All of the hummingbirds I see I get good looks at[if they do anything more than just whizz by]- they're one of my favorite birds so I specialize in them-+ parrots- and I NEVER EVER saw something that was more than green body with varying colors on the rump, tail, crissum, and varying degrees of leg puff- with the exception of violetears, which I found quite distinct and usually pretty easy- mostly by sound: if it goes brrrrt-steek! of brr-brrt-steek! all the time, it's a green, and if it doesnt, check for the blue-violet "ear"- whether it goes under the bill or not.)
As for the second post about the emeralds... the reason you can't make them big is because that IS their size... I couldn't get any better shots, and was just hoping that someone could magically tell from that. Guess not. I would still saw Narrow-tailed Emerald, though, based on range.
Lets see... Bill color. Most of them seemed to have all-black bills, but that was kind of hard to see, as they were poking them into flowers all the time. I think I could see a little red on them at times, always on the bottom mandible, and mainly on the Rufous-tailed Hummingbirds, which were all over.
Tail shape: all the tails were forked, except those of the Violetears- and those were a little forked sometimes too. I'm not experienced enough to know how to describe the degree of forking... but I would guess (I'm not very good at guessing distances or lengths either though...) it never made more than a half a centimeter's difference between middle feathers and outer feathers.
Tail color: they all seemed to have one-color tails- but bicolored coverts- that is, the hummers in question.
Rump: I'm pretty sure that the rump was usually green, maybe with the exception of a coppery tinge, probably from iridescence. The uppertail coverts were blue with a few feathers of rusty color at the base.

And that is about as much as I can squeeze out... now, at least.

Thanks for all your help, Rasmus!