Each year Wake Audubon chooses a bird on which to focus. The species is always one that is found in Wake County and a bird that is under pressure from climate change, development and/or loss of habitat. We learn about the species through articles in our newsletter, lectures, and field trips.
Wake Audubon Society is pleased to share among members and anyone else interested, our exploration of this delightful year ‘round resident of Wake County.
American Goldfinch pair at Mid Pines Road, Raleigh, NC Photo by Phil Doerr
This prim, spectacular pair were seen and “captured” in late July along Midpines Road in Wake County, of course! The male (left) sports his breeding best plumage, as summer is the nesting season for goldfinches. The males sing and display in early summer to attract females and defend territories from competitors. The female (right) is not as bright, a feature rendering them less visible to potential nest predators. They are likely the most seed dependent species we know of, and often forage “weedy” grass and forb dominated areas in fallow fields, and roadsides where infrequent mowing allows wildflowers and grasses to develop.
The goldfinch habit of frequenting roadsides in all seasons, and bird feeders in winter make them one of the most familiar birds in our area. Catkins and seed pods of alder, and sweetgum are another spot to observe goldfinches in winter where they dangle up-side-down on the ends of branches high overhead. So this winter, make it a habit to check out those weedy roadsides, or high sweetgum “balls” where these dainty little birds forage, and give a listen for their high pitched “potato chip” calls especially in flight.
In winter, American Goldfinch females and males really look alike, as males drop the very distinctive black wing feathers and brilliant yellow body plumages. By now (February) males have molted and replaced the bright yellow body feathers of late August w/ the drab plumage
Male American Goldfinch in Winter (photo by Bob Oberfelder)
American Goldfinch female in Winter (photo by Bob Oberfelder)
that will see them through winter. Females do the same but it’s not so noticeable! It’s a definite advantage to be less visible to predators as the birds forage leafless treetops and fields in groups of a dozen or more. Some winters when we have “finch years” goldfinches may be seen in tree tops or at feeders, in the company of a hoard of pine siskins. Siskins are by comparison a bit smaller, and with some yellow wing and tail feathers that contrast with a streaky brown head and body.
Goldfinches (and other finches) that regularly visit our thistle seed and sunflower feeders in winter are known from banding studies to make the rounds of available feeder stations within a 4-mile radius. This behavior seems to decrease the likelihood that the birds will encounter an empty feeder! This semi-nomadic behavior also keeps the birds moving about in more natural agricultural and woodlot areas with seed producing grasses, forbs, wildflowers and a variety of “weeds”. In flight, groups can be heard vocalizing their “potato chip” call. Keep an eye out for these wonderful winter wanderers and see if you tell the males from the females at winter feeders.
Cautionary… There’s a downside to the observed finch behavior we’ll consider next.
The Bird of the Year is a frequent visitor to our late winter feeders, which you may have noticed, often sharing the largess with purple finches this year. So, keep the “nockies” handy to check out your finches! Have purple finches joined, or even supplanted the house finches? Your ever reliable goldfinches will most likely “weather” the purple storm and mingle readily with these boisterous groups.
American Goldfinch female enjoying an icy winter perch (photo by Bob Oberfelder)
But Wait! Be alert! You may recall, that a worrisome, and potentially dangerous situation can develop among these birds when they mob our feeders. Mycoplasma gallisepticum is a bacterium causing respiratory disease in several bird species, including goldfinches!. Mycoplasmosis is especially prevalent in house finches, presenting as red, swollen and crusty eyes. Birds mobbing feeders may, unfortunately, “share” the disease by rubbing against feeders, where infected birds have fed. In harsh weather there may be significant losses, but many birds do recover infection.
So, what do we do? Mainly we keep alert! Watch your birds feeding, relish their beauty and enjoy their behavioral interactions and displays. Learn the secrets of goldfinch plumage change, because “any minute” some males will begin brightening and incorporating some bright yellow in fresh feathers. This awareness also allows us to detect the appearance of Mycoplasma (or other diseases) in any of our finches so we can react! Once detected there are several things to do:
1-Take the feeders down, and clean thoroughly with disinfectant.
2-Keep feeders down for 2 weeks (but no worries, the birds will return within hours of restarting feeding.
3-Contact Cornell Laboratory of Ornithology at Project Feeder Watch (feederwatch.org) to report the disease and perhaps the join the Lab’s Feeder Watch program and learn about the science of bird feeding.
4-When re-starting your feeder program consider increasing the number of feeders, or spreading them to reduce crowding and hence disease transmission. Consider avoiding tube feeders as there are data suggesting this configuration enhances opportunities for disease transmission as birds rub against the feeder while actually feeding. Table feeders can present similar hazard.
5-Plan to take feeders down once a week or so to thoroughly clean, disinfect, and dry.
6-Keep the area underneath feeders clean and free of waste, hulls, droppings etc.
7-Clean and disinfect any water features/baths regularly.
Now here’s another alert. Do not remove or cut out any of the long dead plant stems from last year’s pollinator gardens, flower beds, or so-called “weeds”, and don’t mess with the ground level detritus! Don’t do it!! -Not until spring is really truly here! This is really important! More next month!
Thanks for checking us out! Keep watching our American Goldfinches and all their winter buds!
Thanks for caring for the birds, they do tell us to “Act on Climate!” Spread the word!
April Musings
With the “Ides of March” safely behind us our American Goldfinches have really become just that! Or nearly so! Gold! Lotsa Gold! Recall that our Goldfinches performed a complete molt (replaced all their feathers!) in the fall becoming relatively drab, but males are now, in spring, replacing their body feathers with the brilliant yellow breeding colors! If you’ve been keeping an eye on your feeders, the transition is beginning to show in many males.!
This year, late February to early March was warm enough that daffodils, azaleas, trout lilies, and a whole lot of other spring ephemerals were blooming. We’ve had a really warm, early onset of spring, with a pattern of warm fronts added to general climate warming influences. True to form, March then gave us several cool (cold?) systems that slowed the onset of spring.
The birds do require lots of nutritious seeds to accumulate the energy needed for this transition. In some areas this need may explain the persistence of goldfinches at our seed feeders in spring and early summer. Goldfinches are especially fond of thistle seed, in the wild, and at feeders where during winter “finch years” they may have to battle with large flock of pine siskins for access. A “finch year” is when large numbers of siskins, purple finches, and evening grosbeaks move south for the winter due to widespread food crop failures in northern forests. .
Now, in addition to noting that some of our winter feeder visitors (eg, purple finches, dark-eyed juncos) are departing to return to northern breeding locations, we’re seeing other changes. **
If we’ve been cultivating our native pollinator gardens (maybe even converting portions of our lawns to wildflower meadows?) we might have seen the Goldfinches hanging onto the dried out seed heads of the coneflowers left from last season. And these delightful visits are right down low! The important operative here is that we’ve indeed kept all the dried stems of the native wildflowers and “weeds” from last year all through the winter, and until spring “green up”. This undisturbed habitat is crucial to the survival of all our native invertebrates that will feed all the birds and other wildlife that populate our yards and woods. Many of these micro-critters overwinter in hollow stems or the leaf and grass litter in the garden and woodlot edges.
Furthermore, fireflies and native bees overwinter in the litter and first couple inches of ground cover, so it’s important to leave that substrate undisturbed until these critters have emerged, the bees to seek out early blooming plants. Consider leaving your garden cleanup to the very last moment before you cultivate or freshen for the spring. Generally, we should avoid mulching with heavy materials like wood chips, because most invertebrates are unable to burrow in that medium. An undisturbed light natural leaf mulch is best for most native species.
For now, enjoy the goldfinches at your feeders, and watch for migration arrivals and passing birds in your area. Check out https://birdcast.info for migration forecasts and real-time radar tracking of ongoing migration events. Check your yard and nearby wooded areas daily for overnight arrivals. And remember to observe the Lights Out Wake protocols of dousing exterior lighting between 11pm and 6pm so that migrating birds are not confused and crash into buildings or homes.
If you’ve been fortunate enough to have these dainty little seed-eaters frequenting your winter-spring seed and suet feeder offerings you have likely noticed many of them have transformed to a sometimes blindingly brilliant yellow! These bright birds are of course the males adopting their breeding season colors. While the yellow body feathers are emerging
the buffy wing bars of winter have flaked off, leaving the much brighter white wing bars remaining to enhance the yellow/black contrasts. In late April and May you may be seeing birds that look like this at your feeders! Keep your “nockies” and camera handy!!
Courtship begins in the spring when one or several male birds chase a female. Sometimes several males will chase a female, which allows her to select a mate that demonstrates the best “fitness”, or vigor (=faster, or more aggressive, or??). The female may take off in an apparently evasive maneuver while the male(s) pursue. During this courtship period, a pair (once a choice is made!) may fly in a circular pattern with the male singing. These behaviors may begin in late spring and continue into June. Again, be sure to keep your “nockies” handy when out and about as you might catch the birds engaged in these aerial antics. Also keep in mind these are very late nesters so pair bonding may still be happening in June with actual nesting usually in July or later! The birds seed diet has them waiting ‘till well into summer, when primary seed producers (especially thistles) have matured and there’s plenty to feed growing youngun’s.
American Goldfinches are typically monogamous but some females change mates after producing their first brood. The female may then leave the nest to begin another brood with a new male while the first mate stays to look after the fledglings. This behavior has evolved in many species to allow females some “bet hedging” that may diversify the genetics of her offspring and increase the likelihood some will have the “the right stuff” to enhance their survival probabilities and ensure her lineage continues. And as it happens most American goldfinch populations have more males than females and this strategy helps balance that evolutionary scale.
To signal that his territory is taken, a male will sing and patrol from perch to perch. He may also cruise around the territory and do a low flight followed by an undulating flight with wings close to his body as he dives down and then spreads them again as he flies upward in several loops. At this time the males are truly spectacular as illustrated by these males Bob Oberfelder “captured” in May 2015, and August 2016 when the wings are almost completely black.
Some Goldfinches will choose to nest in small groups in adjacent shrubs or small trees, a behavior that may reflect good seed sources nearby, and suitable nesting substrate. Predator avoidance may also be enhanced with more eyes present. Again be alert, and if you pinpoint a likely nest area with a male singing, look for additional goldfinches and more nesting.
Also watch for goldfinches that may be working low in weedy areas harvesting thistle down and spider webs to use in nest construction. If you spot this behavior, you may be able to see where a nest is being built.
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Thanks for all your interest in birds! And please consider reducing outdoor light use at night
(11pm-6am) all during May when migration traffic often exceeds 200 million birds in motion every night!
July – The American Goldfinch Nesting Now!
Watch for them along woodland edges and shrubby corridors in open fields! It’s July in North Carolina, the heat is building, the milkweed is flowering, thistles are setting seed and the not always patient American goldfinches are ready! Perhaps worried the male will botch the job, female goldfinches build the nest, using 2-3 vertical stems as a base about which she weaves small twigs and bark strips to fabricate a cup. She’ll then line the cup with small plant rootlets and downy materials from thistle seed or milkweed pods. The females collect the cottony down of thistle seeds and milkweed pods to cushion her eggs. She will collect thousands of these to weave into the cup of the nest. The entire project is stitched together with spider silk! And the resulting cup is famous for being so tightly woven it will hold water. Careful scrutiny of the top down view of the nest illustrates her skill.
This construction may take an exhausting week of work, followed by several days of egg laying, to produce the customary 2-7 egg clutch. Sitting the eggs for 2 a week incubation, the female will take occasional feeding breaks, but is often fed by the male . Once the eggs hatch, the male will begin nearly nonstop seed deliveries for the female to pass to the demanding nestlings. Soon the demands escalate as the chicks grow, however, and both parents will feed. After nearly 2 weeks, the nestlings “fledge” (leave the nest) but continue to beg piteously. The male will feed them a few more days, but the female has more important business, now…. It’s been a month or more since she began building the first nest, and her best investment now is to initiate another brood quickly!
So now she will leave her fledglings with the doting dad to finish the job and often, as we mentioned last month, seeks out another spot to initiate a new nest with another male! While this may at first seem a questionable behavior it does have ecological, and evolutionary benefits. First, there’s another 6 weeks of summer weather with an abundance of seedy delights and soft fluffy goodies for nest building, so plenty of time to fit another brood in! Thus, the female has a chance to double the number of offspring with her genes in the annual lottery and add the potential benefits of a second male. She’s a bet hedger! No point in putting your eggs in a single basket when options are available! Second, this strategy also helps to compensate for the unbalanced sex ratio among adults that favors males…it provides an opportunity for more males to breed than could otherwise. Females are often a scarce resource among American Goldfinch populations. There is some thought that females may be worn out by the fall, and grateful for a less demanding life style.
As always, remember the importance of the weedy edges, gardens and roadside fence vegetation in providing the seed crops American Goldfinches need to survive, and which provide habitat for all the invertebrates (insects, and various creepy crawlies) the other birds need! You can convert part of your lawn to native plants, and help all the wildlife!
Thanks for all you do for birds! It is the way.
August – Why Might Some American Goldfinches favor their “firstborn”?
Female Goldfinch
This 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
Bird of the Year Archives