Date: 1/11/18 8:46 am From: Norman Budnitz (via carolinabirds Mailing List) <carolinabirds...> Subject: Re: northernmost Ruby-throateds
I suspect that the question of feeder dependence is as varied as the bird species that use them.
--Species like Chickadees and Titmice are remarkably flexible in their feeding. They certainly make use of feeders when they are available, but if you have ever watched them closely, they are constantly searching every nook and cranny for anything worth eating.
--Cardinals and other permanent resident seed eaters also take advantage of feeders, but are they dependent? I have a couple of color-banded cardinals who visit my feeders every day, so I 'know' them as individuals. But I also have a number of unbanded cardinals who come and go. How many? I always thought perhaps half a dozen. But one year when we had 10 inches of snow, I counted more than 40 cardinals in my yard at one time, all waiting for a turn at the feeders. Did I just have every cardinal in the neighborhood that day? Or were those same birds coming to my feeder all along, just never concentrated like that? Were they dependent on my feeders or just taking the easy way out, given the snow conditions?
--The northward expansion of the range of cardinals began in the middle of last century, coincident with the rapid expansion of bird feeders. When I was kid, having cardinals at my feeder was very special. Now they are thoroughly established. But mockingbirds have also expanded northward, and they are not feeder birds. So is it feeders? Is it human induced changes in habitat--for example residential plantings? Is it global climate change? Is it all of the above?
--Hummingbirds are tiny and require lots of carbohydrates and protein (and probably fat) to make it through each 24-hour period (nighttime torpor helps). But there are many more insects out there than you might expect. After all, kinglets are insectivorous and most of them never come to feeders. Golden-crowned Kinglets make it through sub-zero, snow-covered Maine winters by finding over-wintering caterpillars on tree branches. Hummingbirds are not kinglets, but the more cold-hardy hummer species are probably well-adapted to finding insects out there, even on the coldest days. Less hardy species like the Broad-billed Hummingbird that was in Southern Shores NC are probably not as well adapted to finding wild food sources this far north. Each species has its own adaptive strengths and constraints.
--As Susan has noted, many of these species, particularly the migratory ones, are well-adapted to moving around. Times get tough? Go somewhere else. If you have stored enough fat, you should be good to go. If not, um, well, natural selection comes into play. Migratory species and nomadic species (think siskins and crossbills) simply move on. Resident species solve the problem by being flexible. Both take advantage of feeders when available.
--So after all this ranting, what do I think? Yes. And no. Feeders probably do play a part in the range expansion of some species and probably have no influence on other species. You can probably substitute 'human-induced habitat changes' for 'feeders' in the previous sentence and it will still be true. Or 'climate change.' If we suddenly stopped putting out sugar water, would those coastal hummers stop coming north in the numbers we see now? More to the point, would we know that they were no longer coming north? Or would they simply escape our notice because they wouldn't come to our backyards very often?
--The evolutionary question is this? Does feeding birds result in more offspring for the individual birds so provisioned versus those individuals with only natural food available? Do the hummers in John's yard all winter go on to breed and have grandchildren more than, as much as, or less than the hummers that never come north at all? How will we ever know?
Phew! Enough for now. If you have stuck with me through all this, thanks. If not, well, you won't read this sentence anyway, so it doesn't matter.
On Thu, Jan 11, 2018 at 10:12 AM, "J. Merrill Lynch" <carolinabirds...> > wrote:
> I will be interested in your thoughts on this given your powers of > observation and your many years living on the coast. > > Despite the comments to my post, I remain convinced feeders have had a > major influence on wintering ruby throats. To what degree is the question > when weighed against climate change and other factors. Would make a really > good research project! > > Merrill > > J. Merrill Lynch > Conservation Biologist > Echo Valley Farm > Watauga County, NC > Sent from my iPhone > > > On Jan 11, 2018, at 8:39 AM, John Fussell <jofuss...> wrote: > > > > In the wake of the rain/sleet/snow and sharp cold spell, I would be > interested in knowing where the northernmost Ruby-throated Hummers in the > state are now. > > > > Kelly Davis at Mattamuskeet has two, as does Ann Maddock at Cape > Hatteras. Here in the Morehead-Beaufort area there are a few birds, > although not as many as before the bad weather. > > > > Are there any other Ruby-throateds north of Morehead-Beaufort, other > than the ones cited above? > > > > Have numbers also decreased in the Wilmington area? > > > > Just curious. > > > > I also have some comments about whether or not feeders keep hummingbirds > from migrating south; I'll get around to posting those later. > > > > John Fussell > > Morehead City, NC >