Authored by Phil Doerr
Hopefully some of us are out seeing numbers of recently fledged juvenile American Goldfinches like this hot (panting) youngster Bob Oberfelder “captured” for us recently!
American Goldfinch baby, Cary, NC
Post nesting, Goldfinches of all ages tend to spread out across local landscapes with early to mid-successional vegetation, supporting lots of seed producing “weedy” species! Goldfinches will soon begin to aggregate in small foraging groups and make the rounds of suitable seed patches. In a few weeks they will begin the fall molt to winter (duller) plumage and begin to all look alike! In our part of the world, goldfinches are a bit nomadic, but definitely not really migratory. Birds nesting much to the north do migrate to our area or even much farther south for the winter. The need for seeds in our increasingly dormant pollinator gardens, roadsides, and field edges will increase as fall edges into winter.
Will NC lose our 2023 Bird of the Year as a Breeding Bird? Various climate change scenarios predict that in the NC piedmont we may lose our nesting American goldfinches as the environment becomes too hot and dry to support nestling survival. We may only see these delightful creatures as winter residents from the north, absent the spectacular breeding plumage males. Check out “Audubon Guide to North American Birds” on line for American Goldfinches and scroll down to “How Climate Change will reshape the range of…” As we are now on a trajectory to hit a 1.5 degree C global temperature increase, American Goldfinches will most certainly lose 34% of current breeding range, will only nest in our higher, cooler mountain areas, and if we fail to keep below a 3 degree C increase goldfinches will no longer nest in North Carolina at all, while losing 65% of current U.S. breeding range. The interactive Audubon website allows you to play out the resulting scenarios for each combination. Please explore! You will also see another side of this dramatic change, because while goldfinches lose much suitable breeding range in the US, they gain some suitable habitat to the north, much of it in Canada. Most North American breeding birds are facing similar challenges in the face of looming climate change.
While American Goldfinches may still winter in North Carolina, we may need to travel north to witness the stunning plumage of males in courtship and nesting in the future. Goldfinches do seem likely to fare better than most North American breeding birds, however. Most birds will lose much more habitat than will be gained by the northward march of a warming climate. Audubon report models predict 389 bird species will be at risk of extinction under the 3 degrees C. warming scenario.
And while it’s true that ecosystems are often in flux and ever changing, this current change is not natural! It is the unfortunate result of our callous disregard for the health of the planet and continued dependance on fossil fuels. We are fouling our nest and killing nature in the process.
We’ve just experienced the hottest July ever recorded on earth, while 2023 so far is filled with the one of the largest tallies of catastrophic weather events, ever. Most of these events would have been impossible before global climate warming.
So, what can we do? We must insist that our governments adopt policies for conversion of all energy use to renewable sources and we must be conservation minded in our own use of energy. Period! That’s it! No more fossil fuels!
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Remember “Lights Out Wake” begins September 10, continuing ‘til November 30, when we will pledge to douse all nonessential lights from 11pm to 6am to save our migratory birds and money! Check out “Birdcast.info” for real time updates on migration!
Thanks for doing all you can for the birds.
Phil Doerr ([email protected])
Wake Audubon Board
Authored by Phil Doerr. The female goldfinch has by now had over a month of “nesting”, including the demands of nest construction, egg laying, incubation, feeding chicks, and finally perhaps taking a break to fuel up for the fall molt and winter flocking with her “mates”….or she might start all over again with another male, in pursuit of her optional“bet hedging” reproductive strategy. This is the option where she produces a second brood with her genes plus the genes of a second male. Consequently, there are more young and there’s more genetic diversity among those young, all pluses, providing she can pull it off.
Curiously, American goldfinches may utilize a strategy peculiar to a relatively small number of bird species. This strategy involves invoking asynchronous hatching of the brood. So, one might reasonably ask just what is asynchronous hatching, and why does it happen?
The great majority of birds have evolved the reproductive habit of laying the “usual” number of eggs before the hen (usually!) begins to sit, and incubate the eggs. This continous attentive behavior keeps the eggs warm, and the embyoes growing until hatch time. And because the incubation of the eggs by the warmth of the hen began simultaneously the eggs all reach developmental maturity simultaneously and hatch at the same time. Why is this synchronous hatching such a commonly evolved reproductive strategy? Certainly it’s a plan that works well for waterfowl or game birds that all need to leave the nest at once and head to the water, or the bush! These chicks are precocial, meaning immediately mobile and able to feed for themselves. It also works well among birds for which nesting season food supplies are reasonably reliable. When the young are suddenly present all at once, the adults are motivated to bring home lotsa groceries to keep all the demanding “gapes” happy. Adults are, in fact, programmed by evolution to keep stuffing food into the always open gullets! This behavior also explains why a tiny common yellowthroat may be observed attempting to satisfy a much larger (and parasitic) brown-headed cowbird chick! And as long as there is always plenty of food, this system works well. Sometimes, however, adults may experience difficulty finding enough food and then all the chicks are likely to die, resulting in a missed breeding season. One might speculate that if an adult bird could “decide” to feed just one or two of the several chicks in the nest, they might survive while the others would die. An unhappy consequence for some, but at least the adults would produce some young that year.
Asynchronous hatching is an alternative strategy that may result when a female begins incubating before all her eggs have been laid…this is a “decision” that may happen by natural selection when variabity occurs. That is, while most females lay all their eggs before initiating incubation, sometimes a female may start to incubate when the second or 3rd egg is laid.
The outcome is that some embryoes start to develop a few days sooner, and hence hatch a few days before the others. The early hatching chicks get a real jumpstart on their nest mates, often monopolizing food at the expense of smaller mates to the extent they may not survive, and this may be particularly advantageous during a food shortage.
Asynchronous hatching is a strategy that has evolved in a number of raptors and other large birds, as an effective way for relatively long lived birds to produce at least one young in most years. Consequently, many hawks and falcons are among the most familiar groups displaying ansynchronous hatching, given that prey abundance and availability can be notoriously unpredictable. A first hatched, first served, strategy that awards advantage to those first in line!
An important question concerning American Goldfinches is “are there summer seed shortages dramatic enough, or frequent enough to provide a selective advantage?” There’s not much evidence for this, only the fact that because asynchronous hatching does occur regularly, there might an advantage often enough, that the trait persists in the population. Such uncertainty suggests an opportunity for more research to explore asynchrony in goldfinches.
Asynchrony allows some female goldfinches to favor their “first born”, but just why seems an elusive answer!
Thanks for reading, and thanks for all you do for birds. Remember that all those seeds in your “weeds” are important groceries to birds, and to the critters birds eat!
Phil Doerr ([email protected])
Wake Audubon Board