Today I'm going to talk about... hummingbirds. Actually, I'm only going to talk about hummingbirds here, so if you need a break from politics, national crises, or washing dishes -- well, you're in the right place!
Hummingbirds are incredible little creatures. They're only found in the New World, although there is fossil evidence that in the past they may have occurred in the Old as well. They thrive in extreme habitats, from dusty deserts to dense rainforests and remote mountaintops (did you know there's a Volcano Hummingbird?). They can have beaks as long as their body, and tails much more so. Some of them have a rather flamboyant sense of fashion or are part-time dancers, while others seem to take life more seriously. But many of us know about these living jewels simply because they can be found right at home, in our own backyards, and they seem to appreciate the flowers and food we put out to attract them.
There are many kinds of hummingbirds -- around 340 species -- but I'm going to focus mainly on those regularly found in the United States and Canada. Specifically, I'm going to focus on the hummingbirds in this area which are known to hybridize with one another.
What is hybridization? (No, I am not talking about fuel-efficient cars here!) According to the Merriam-Webster Dictionary, a hybrid is "an offspring of two animals or plants of different races..., breeds, variety, species, or genera" (see link). In this case, it refers to a cross between two species, say, an Anna's Hummingbird and a Costa's Hummingbird. More well-known examples of this include the mule (a cross between a horse and a donkey) and the liger (between a lion and a tiger).
Here's the typical notation for a bird hybrid, excluding scientific name:
Anna's x Costa's Hummingbird
To save space, the word "hummingbird" is not repeated. Also, at least with birds, the first-mentioned species is not necessarily the father, and the second is not necessarily the mother -- or vise versa -- as this is usually difficult to impossible to determine in the field. Rather, the species mentioned earlier in the hybrid name has an earlier sequence on the evolutionary tree, while the second-mentioned species appears later (see link).
So, what are these hummingbirds, and what scandals occur in their world? Let's start with the:
Anna's Hummingbird (Calypte anna)
Anna's Hummingbirds are a common Western species, found most notably in Washington, Oregon, California, and Arizona. They are medium-sized, hummingbird-wise; the male has a bright magenta-pink head and is emerald green above, with some clean gray below. The female is green above and gray below with a small amount of speckling on the throat. To be honest, I will not be talking about female hummingbirds much here, since they can be difficult to identify even without bringing hybrids into the mix!
Let's take a look at some pictures.
© Kyle Blaney/Macaulay Library at the Cornell Lab
ML45345081
https://macaulaylibrary.org/asset/45345081
This is a male Anna's Hummingbird; the female is below:
© Matt Davis/Macaulay Library at the Cornell Lab
ML73136521
https://macaulaylibrary.org/asset/73136521
© Kent Forward/Macaulay Library at the Cornell Lab
ML90382651
https://macaulaylibrary.org/asset/90382651
Note that the color of these iridescent throat and crown feathers can change dramatically with lighting. The reason behind this is very interesting and boils down to the feather's microscopic structure; you can read more about that subject here. Importantly, when hummingbirds hybridize, the iridescent throat color (known as the "gorget") of the resulting hybrid is often intermediate between the two parent species. However, you must be cautious when assessing a potential hybrid, as light can change the color of even a "pure" bird! Multiple angles and good lighting are ideal for determining whether the throat color is truly intermediate.
Now, before I get into the Anna's Hummingbird hybrids themselves, I would like to discuss a very important but perhaps under appreciated element of hummingbird ID. Take a look at the two illustrations below (adapted from The Sibley Guide to Birds by David Allen Sibley).
What do you notice about these two illustrations? Can you point out some differences when there isn't any color?
To note a few things, the hummingbird on the top has a more streamlined barrel- or tube-shaped body, especially compared with the more "dumpy" look of the bird on the bottom. The top bird has a straight bill, while the one on the bottom has a somewhat downcurved bill. The top bird's tail extends past the wingtips, while bottom bird's does not. Finally, the bird on the top has a particularly large-looking head, even more so than the bird on the bottom.
All of these things add up to a different impression, unique to each species, and you should always keep shape in mind when looking at any hummingbird, especially a potential hybrid. (By the way, the bird on the top is an Anna's Hummingbird, and the bird on the bottom is a Costa's.)
Now that we've considered shape, let's move on to an actual hybrid. For now let's just look at one example: the Anna's x Costa's Hummingbird!
For reference, here are a few photos of pure Costa's Hummingbirds:
© Gordon Karre/Macaulay Library at the Cornell Lab
ML47682281
https://macaulaylibrary.org/asset/47682281
© Daniel Irons/Macaulay Library at the Cornell Lab
ML109782961
https://macaulaylibrary.org/asset/109782961
© Andrew Core/Macaulay Library at the Cornell Lab
ML82550311
https://macaulaylibrary.org/asset/82550311
Once again, notice the "dumpy" shape and small stature of the Costa's. The male has one pretty clear difference: he has a royal purple, not pink, throat and crown. His gorget (colorful throat patch) is also noticeably "flared" (extended) at the lower corners.
Aaaand finally.... the hybrid, in a front-on view:
© David Rankin/Macaulay Library at the Cornell Lab
ML35590081
https://macaulaylibrary.org/asset/35590081
Notice David Rankin's comments from the Macaulay Library specimen page:
Here's two photos of a different individual, same type of hybrid:
© Peter Svensson/Macaulay Library at the Cornell Lab
ML85582511
https://macaulaylibrary.org/asset/85582511
© Breck Tyler/Macaulay Library at the Cornell Lab
ML85615261
https://macaulaylibrary.org/asset/85615261
Once again, the gorget color is an intermediate purple-magenta. The body shape is also heavier than Costa's, but a little lighter than Anna's. Can you notice any other intermediate characteristics?
That's it for now! Let me know what you think, and keep looking up!
Marie
