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The height of summer is upon us. Amidst the heavy haze the happy green hum of life reverberates throughout the fields, meadows and forest. Wildflowers, at their peak under the solar spotlight, are tended by busy bumblebees, honeybees, tiger swallowtails, spangled fritillaries and red admirals. Hummingbirds join the dance as they flit about like garden sprites. Cicadas lend an appropriately incessant voice to the heat; they are the chorus of summer’s daytime song. The lazy, undulating “per-chik-oree” call of the sweet goldfinches and the begging calls of their young signal the close of the avian nesting season.
That’s right! Acorns are dropping, blackbirds are flocking and fall songbird migration is just around the corner. In fact, beginning in September the Rushton bird banding station will be open Tuesday and Thursday mornings for public visitation between the hours of sunrise and 11am. Fall migration extends through the first week of November.
The Rushton banding crew just packed it in for the summer MAPS (Monitoring Avian Productivity and Survivorship) season. The final week in July marked the last of the eight summer banding sessions required each year for this banding project, the aim of which is to understand the breeding birds of Rushton and how their population changes from year to year. This year was our fifth MAPS year and it turned out to be the best! We processed 249 birds —7 more birds than our 2011 record of 242. In each of the three years in between, we didn’t make it to 200 birds.
We couldn’t have been more thrilled with this season’s catch. All summer long the forest rang with abundant, ethereal songs of Wood Thrush and Veery, and baby birds abounded! Breeding species included Ovenbird, American Robin, Gray Catbird, Tufted Titmouse, Wood Thrush, Carolina Wren, Downy Woodpecker, White-breasted Nuthatch, Veery and Common Yellowthroat to name a few. Below are some mug shots:
The Gray Catbird—named for it’s mewing call— always makes up the bulk of our catch, so we call it our “bread and butter” bird. Without it, sometimes we feel we’d be “out of business”!
It’s easy to take this common backyard bird for granted, but it is actually quite a fascinating little bird. Catbirds are a widespread species nesting in 46 of the lower 48 states as well as southern Canada. Some winter in the Gulf Coast and Florida with others traveling farther south to Mexico, the Carribean and Central America where they share the forest with jaguars, toucans and pit viper snakes! The Catbird is one of the few well-traveled birds that will nest in a shrub in your yard rather than requiring a remote woodland like many other neotropical migrants that just pass through.
Catbirds are also one of the few species that can learn to recognize and eject speckled brown cowbird eggs from their nest of beautiful turquoise eggs. The Brown-headed Cowbird is a parasitic species that lays its eggs in other birds’ nests, thus avoiding all parental care! It can be a real problem for the nesting success of some already threatened species like Wood Thrush (65% population decline since 1968) that don’t recognize and eject cowbird eggs. Cowbird babies often out-compete the thrush chicks. This is one of the reasons why unfragmented expanses of forest are so important; deep woods give Wood Thrush a bigger buffer zone against shady cowbirds that prefer edge habitat.
Studies have shown about a 60 percent annual survival rate for catbirds, but if they do survive the winter and migration, chances are the same wily catbird will return to your yard. (Many songbirds exhibit this site fidelity). The oldest catbird was almost 18 years old, banded as a chick in Maryland and recaptured that many years later by bird banders in New Jersey!
During MAPS this summer we were surprised to recapture one of our banded Gray Catbirds that was originally banded by us in 2010 as an after-hatching-year bird, meaning it was at least in its second year back then. That means this bird is at least 7 years old now! It’s marvelous to think that this migrant has been so successful and made it back to Rushton Woods every summer. This is especially significant to us because most of Rushton’s Gray Catbirds are young and inexperienced. Hopefully, he’s teaching ’em a thing or two!
If you recall, this spring was very cold and long. All of the trees and flowers were running a couple weeks late, and allergy season lasted longer as well. This weird weather did not make for an exceptional spring migration. We banded 344 birds of 49 species (compared to 449 birds the previous spring).
Interestingly, we actually still had migrants, like a Gray-cheeked Thrush, roaming the woods of Rushton during the first week of MAPS banding at the end of May when Rushton’s breeders were kicking off their nesting season. The Gray-cheeked Thrush is a reclusive bird that nests in dense stands of spruce and balsalm fir in cool boreal forests of Canada (the nursery of an estimated 3 billion North American songbirds of over 300 species). As one of the most northern nesting species that visits Rushton during migration, we shook our heads in awe thinking about the many miles the thrush had yet to go. Click here to learn more about the importance of and threats facing our boreal songbird nursery.
Anyway, not all of our birds were gray this spring. Even though overall numbers were slightly down, the species diversity was satisfying and some species had increased. Orioles, including Baltimore and Orchard, were more abundant this year than ever before—a tribute to the flourishing farm edge habitat that orioles love. Such enticing border trees may not have been spared on a typical large-scale, conventional farm.
An American Woodcock—also grateful for the respect of our sustainable farm on the surrounding thicket habitat— graced our nets this spring with its alien eyes, prehensile bill and giant shorebird feet!
Some other favorites of this spring’s catch included a pair of no-neck, aerodynamic, bug-gulping Barn Swallows and a handful of spectacularly handsome Blue-winged Warblers, a species that we haven’t caught since 2010. In fact, we think we might have had some Blue-winged Warblers nesting at Rushton this year because we heard their “bee-buzz” song well into June. A bird of old fields and shrublands, it should find a happy home in Rushton. Another bird with similar nesting habitat requirements, the Prairie Warbler, was also heard singing off and on from the fields this spring and summer, possibly indicating nest activity. These could be two new breeding species for Rushton; it’s a good neighborhood and the word is getting out!
Blue-gray Gnatcatchers were omnipresent this spring, and quite a few of the little things ended up in our nets. At only 5-7 grams, they can construct their nests with delicate materials that hummingbirds use, like spiderwebs and lichen.
A little disconcerting was the absence of a wood warbler that is usually one of Rushton’s most common warblers during migration: the Black -throated Blue Warbler. We normally band 10 of these each season, but only one checked into the station this spring. Could this indicate a problem like habitat loss or a weather event on the wintering grounds in the Carribean?
We couldn’t have known what a productive summer this would be by simply looking at the results of this year’s sub-par spring banding season. We might have had a better idea if we’d known about habitat conditions for our birds where they overwintered. Studies of migratory connectivity are now illuminating the importance of the wintering or nonbreeding grounds in determining the success and behavior of a bird on its breeding grounds.
For example, if a female bird overwinters in poor habitat, she may be underweight and have to delay migration. Delayed migration means getting to the breeding grounds after all the best males are taken (with the best territories). Now left with the dregs, she may have a low- success breeding season or be forced to seek extra-mate copulations with higher quality males to make up for her losses.
Migratory connectivity is the annual movement of birds between summer and winter locations, including stopover sites—those habitats of plentiful food and shelter that are critical for resting and refueling. Knowing what’s going on in the entire year in the life of a bird is fundamental to being able to understand and protect it in the long-run. For this reason many scientists are now combining traditional banding with modern tracking technology like satellite transmitters and light-level geolocators in order to better understand avian movements.
This combined approach has recently revealed that our backyard catbirds— the mid-Atlantic and New England breeders—are Catbirds of the Carribean! They also may overwinter in Florida, whereas the Midwest population overwinters in Central America.
The strength of migratory connectivity varies from species to species, which has important conservation implications. For example, a species exhibiting strong migratory connectivity means most of the population may overwinter in one small area rather than spreading out though a larger range. These species may be more susceptible to climate change or habitat loss.
Take a virtual walk in the woods with an ornithologist in New Hampshire to learn about the migratory connectivity of a small songbird that also breeds in the woods of Rushton; click here to watch the 3- minute video by the Smithsonian Migratory Bird Center of the recapture of an Ovenbird with a GPS tag! GPS tags have only recently become lightweight enough to be used on small songbirds. They have more accuracy than geolocators because they collect data from satellites rather than measuring light levels to estimate location.
Radio transmitter tags are also emerging on the cutting edge of wildlife tracking because they are lightweight and relatively inexpensive compared to GPS. The animal does not have to be recaptured to retrieve the location data; it just needs to pass by a receiving tower. This spring 36 Gray-cheeked Thrushes were tagged with radio transmitters in Colombia, many of which were soon detected by towers in North America! One awe-inspiring individual flew 2,019 miles from Colombia to Indiana in 3.3 days, which means it flew 3 days straight with only an hour or two of rest! Click here to see the map of this astounding feat.
Technology, bird banding and passionate field scientists are unraveling the mysteries of migratory connectivity, thus making conservation of our declining feathered Earthlings that much more tangible. Could such technology be coming to a banding station near you in the future?
If you can’t wait to get out to Rushton to see the bird banding, watch this video to get up-close looks at beautiful songbirds at a banding station similar to Rushton, on the coast of Texas. You will be moved by their take on migratory connectivity and the faces of the local school children getting to release these inter-continental creatures.
There’s a lot going on in the woods,
Blake
