Saturday, November 16, 2013

The trouble with hummingbirds...

Hummingbirds are cute aren't they? It's tough to argue with that. Hummers are everyone's favorites; they're tiny and thus non-threatening, they are brightly colored and they have fascinating lifestyles. And perhaps above all, their unique hovering flight style as they work their way around the flowerbeds is certainly entertaining. Yep, everyone loves hummingbirds. Except perhaps for those unfortunate birdwatchers who find themselves serving a term on a bird records committee! And that's because hummingbirds can be just so darned hard to identify!

When I say hummers are hard to identify, I don't mean those stunning males with their scintillant throat patches, I'm talking about the youngsters that have a nasty habit of turning up late in the fall - and often way outside of the normal range for the species. In the east, we are pretty hard done by for hummingbirds; we have just one species - Ruby-throated - which breeds east of the Mississippi, while west of that mighty river a much more impressive 13 species breeds, with a further five species occasionally wandering across the border from Mexico (please don't take me too hard to task if I've miss-counted by one or two, it's just a guide!). Despite this dearth of breeding hummers in the East we do pretty well for personal appearances by individual birds and this is, at least in part, due to a tendency for these birds to wander great distances outside of the breeding season. The commonest wanderers to our region are those with the longest migration routes and, as is the case with most vagrant species, young birds, migrating for the first time, are likely to make up the bulk of the birds that turn up.

For the past 20 or 30 years, vagrant hummingbirds seem to have been steadily increasing in number in the Eastern USA, and November generally seems to be the peak month for them to appear. There are many opinions on why this should be, but a lot of concensus centers on the possibility that birds are increasingly coming east because they are supported by the hummingbird feeders that are left out later and later. And so it becomes self-sustaining - birders on the look out for rare hummers leave their feeders out so that the rare hummers that turn up find food.

So, to cut to the chase. Yes it's great to have rare hummers turning up, but we birders need closure; we need to be able to identify the hummingbirds to species so that we can count them on our lists. More importantly, identifying these late-season hummingbirds to species is important if we want to study bird movements - migration trends, shifts in distributional patterns and a whole lot more. And now we hit the wall, and it's been a big wall this November, because the phone at the office here at CMBO seems to be forever ringing off the hook with folks calling in to report a late hummingbird in their yard. Don't get me wrong, we want to hear from you if you have a hummingbird in your yard in November, but the real problem comes with identifying it. So please do let us know if you have a hummingbird in your area here in New Jersey right now, but do try and help us with photos if you can - and the photos wil ideally need to be pretty good close-ups. To give you an idea of the problem, here's some photos of recent hummingbirds around Cape May, with some comments on what to look for.

As with all identification issues, you should start by knowing your local birds as best you can. So start by understanding Ruby-throated Hummingbird and start by having a list of points that you know you need to look for. With hummingbirds, important areas are tail shape and tail pattern, wing shape, throat color and pattern and overall colors - especially the amount and distribution of greens and oranges. On top of all this, structure is important, especially of the primary flight feathers and of the bird overall. I know, it's a lot to remember!!

Step 1. Know your local birds. Ruby-throated Hummingbird is the 'default' hummer in the east, so it is a good idea to know it inside out, especially in late fall. At this time of year, most individuals are likely to be immatures. Familiarize yourself with the overall rich green appearance of the upper parts, the lack of rufous in the tail and the light speckling on the throat. This bird can be safely aged as an immature because it is in fresh plumage with neat, crisp pale fringes to the upperparts; at this time of year, an adult would be in worn plumage and look relatively scruffy. In this individual, the relatively long, well forked tail suggests that it is a male [photo by Mike Crewe].

Ruby-throated Hummingbird, immature in fall. The same individual as above. Here's a trap for the unwary - the pink coloration below is caused by reflected light from the bright red feeder beneath the bird. Such things are always worth bearing in mind, but can be allowed for by taking many photos under different light conditions and from different angles. That way you are not fooled by such artifacts [photo by Mike Crewe].

Adult male Ruby-throated Hummingbird - sadly a window casualty. Adult males are easy to identify on plumage alone, but this individual gives us a chance to see the wing structure of this species. Here, each of the 10 primaries is numbered, with the number being placed close to the tip of each feather. Notice how primaries 1-6 are much narrower than 7-10 (though 10 narrows down to produce a tapered point to the feather). Seeing this in the field can be very difficult, but can be very useful in narrowing down the possibilities when faced with a fall hummingbird. Now that you know about this feature, look for it in the picture above this one. [photo by Mike Crewe].

So you look at your feeder and see a hummingbird feeding there. This photograph was taken just a couple of days ago in a private back yard in North Cape May. We can see a couple of things here that look wrong for a Ruby-throat. Firstly, there's quite a lot of rich rufous coloration on the flanks and secondly, a really careful look at the wing reveals a different structure - see next picture [photo by Mike Crewe].

Zooming in on the wing, we can see that there is no significant difference in width between the inner (3-6) and outer (7-10) primaries. I've marked around the tips of the primaries in red so that they stand out. Note that primary 10 is dislodged and would normally be tucked behind 9. Note also that 1 and 2 are missing as the bird is starting its primary molt. [photo by Mike Crewe].

Another phone call, another garden, also in North Cape May. This bird shows similar amounts of rufous on the sides as the bird above and now we can see the tail. Ruby-throats never have rufous in the tail so we know we are onto something good. In fact both these birds show all the signs of being either Rufous or Allen's Hummingbirds. Now we are in big trouble, for unless your bird is an adult male, telling these two apart can be almost impossible in the field without a lot of luck. There is the subtlest of differences in the width of the outer tail feathers between the two species (well shown here) and this bird does look consistent with Rufous. Thankfully, the two can be told apart by differences in their calls and both birds could be identified on call as Rufous Hummingbirds. Further to this, careful examination of many photos of the two birds revealed them to be almost certainly the same individual and it transpired that the two gardens were barely a third of a mile apart as the hummer flies [photo by Sam Galick].

Another shot of the Rufous Hummingbird in North Cape May yesterday. A Rufous/Allen's Hummingbird is the most likely hummingbird to be found in November in Cape May and the rufous coloration in the tail and flanks is pretty easy to see. If you can get good close photos from in front, the side and behind, plus good shots of the primaries - you could be in luck with an identification. Note on this shot another subtle feature of this pair - a thin, rufous brow line above the eye [photo by Mike Crewe].

Back to basics again. This is one of two rather drab hummingbirds that have been gracing a property in Del Haven recently. There's no rufous in the tail on this bird so it's not a Rufous/Allen's, but shows all the general features normally associated with Ruby-throated. With a bird like this, the confusion species is the closely-related Black-chinned, so that's what we need to check for. As with all hummers, we should first try to identify the age and sex of a bird before considering species. The narrow but clear pale tips to many of the upperpart feathers and overall neat appearance of the plumage indicates that this is an immature not an adult, while the rather clean, almost unspotted throat suggests that it is a female (this can also often be backed up with tail shape if a full set of photos is obtained). Telling immature female Ruby-throated from Black-chinned can be very difficult; there are some very subtle differences in the tail that can be hard to see except in the hand and the bill on Black-chinned averages slightly longer and slightly more down-curved, but there is some overlap. Both show the same structural pattern of narrower inner primaries as illustrated above. Perhaps the clearest distinction is the shape of the outer primary tips and this is where correct sexing of the bird is important as it only works in females. Female Black-chins have oddly squared off, almost club-shaped tips to the outer primaries which give the wing a peculiar, heavy-ended look. This does not appear to be the case here, if you look at the left wing tip - poking out above and behind the tail, so this appears to be a Ruby-throated which actually makes it an interesting bird this late in the year [photo by Sam Galick].

One final note of caution, lest we think we are beginning to make it look easy! Let's work through this bird, photographed recently in Cape May County. Neat plumage and narrow, pale fringes to the upperparts immediately tell us it is an immature. A lack of rufous on the flanks (but for a small buffy patch below the wing) and in the tail rule out the Rufous/Allen's pair, as well as the possibility of Broad-tailed, while other pictures revealed narrow inner primaries. This is a Ruby-throated/Black-chinned and, luckily for us, the heavy markings on the throat make it a male. The dull gray color of the crown and dull olive rather than emerald green back all point to Black-chinned. A find indeed, if that's where it ended; but persistence through repeated and prlonged viewing rather than a rapid assessment is what is always required and further studies of this bird left us all scratching our heads a little - more to come later, but think about hybrids...[photo by Mike Crewe].

We would love to hear from you if you have a hummingbird presently visiting your garden and we will see if we can get it identified for you. Keeping records of such occurrences is of value to us in learning more about bird migrations and populations. It may be possible to have someone check out your bird if there is a birder close by, otherwise, we may need you to get out the camera - time to go back over the pictures again!