Jim Williams has been watching birds and writing about their antics since before "Gilligan's Island" went into reruns. Join him for his unique insights, his everyday adventures and an open conversation about the birds in your back yard and beyond.
The chimney that provided me with a Chimney Swift nest last year has done so again. A friend helped me Wednesday morning take photos of and then remove the nest from the chimney. That involved some gentle pry work with a spatula. These birds have adhered their nests to the brick surface just above the fireplace floor and just below the metal chimney liner. A rough surface is needed for nest placement. The birds’ saliva is the glue that holds the nest in place and together. The nest sat about 10 feet down from the chimney opening and two feet above the fireplace floor. It was easily reachable. The chimney lining is evident in the photo. We’re looking at the nest from the bottom. What appears as the bottom edge of the nest in the photo is actually the front lip of the nest. The nest was surprisingly shallow, and had a slight downhill slant. The nest projected three inches from the brick, and is four inches across. The cup that held the young birds — normally four in number — has a diameter of about two inches. That’s pretty cozy. This nest held some egg shell pieces. There was no evidence on the fireplace floor of birds ever using the chimney. Young swifts produce their waste in fecal sacs that are removed by the adult birds. The birds, their sounds first mistaken for bats, could easily be heard while the nest was active. The swifts have returned to this chimney for several years without a miss.
Cowbirds and buffalo might not be as closely involved as we think.
Two weeks ago the birding column in the Home and Garden section of the StarTribune focused on cowbirds. I repeated the commonly held belief that cowbirds adopted their brood-parasite habit via their relationship with buffalo. Cowbirds fed on the insects and seeds disturbed by buffalo herds. Since those herds were always on the move, cowbirds could not nest in the usual fashion. While the birds were incubating and feeding hatchlings, the buffalo were moving on. So, it has been believed, cowbirds evolved into brood parasites: birds that lay their eggs in the nests of other birds, letting the host hatch and raise those chicks.
Roger Everhart, a birder in Apple Valley, wrote to tell me of new information that casts significant doubt on that idea. HIs information comes from an email post made to a national birding chat line by Alvaro Jaramillo, a senior biologist at the San Francisco Bay Bird Observatory. Jaramillo wrote of study of cowbird DNA by Dr. Scott Lanyon, professor and head of the Department of Ecology, Evolution, and Behavior at the University of Minnesota.
The upshot is the suggestion that Brown-headed Cowbirds, while they did follow buffalo herds, were parasitic before they ever found buffalo. This suggestion is based on age of the cowbird lineage, as determined by the DNA study. Jaramillo wrote, "Parasitism in the cowbirds may have evolved due to coloniality, and the safe predator-secure nests of the hosts, among other factors." (Coloniality: birds nesting in colonies.)
Jaramillo continued, "Basically, it (the evolution of brood parasite behavior) is still a mystery. However, the fact that brood parasitism has evolved in several unrelated groups such as cowbirds, two cuckoo lineages, many other birds, and even aphids it is clear that this is a good way to make a living."
The pair of Canada Geese nesting on a platform in our pond brought six goslings ashore Monday morning. The goose gave up on incubation of a seventh egg. She kept at it for 36 hours beyond the appearance of the six that hatched. Strangely, while the egg was clearly visible in the nest during the birds’ initial visit to our yard, it disappeared later in the day. I’m going to have to visit the nest to see if the goose buried it, pushed it into the water, or what else might have happened to it. The goslings were on land half a dozen times today to eat, meals of corn and sunflower seeds beneath our feeders alternating with next of greens and bugs along the pond shore. We have yet to see return of the Wood Duck and Hooded Merganser and their ducklings. I hope the geese stay here. They’re fun to watch.
Update: Monday 7:30 a.m. -- no visible progress from what is reported below. Now into Day Two, the goose continues to incubate at least one egg, the gander continues his watch at her side, and the four or five goslings hatched about 24 hours ago appear restless to get out from under mom and hit the water.
The Canada Goose nesting on our pond hatched eggs Sunday, with at least one gosling yet to make the break. We count five hatched goslings, probably, maybe six. And one unhatched egg for certain, maybe two. A usual brood is five to six goslings. The goose is sitting most of the time, so progress is a secret. The gander has stood on the nest platform, at her side, on alert the entire day. I first saw them at 7:30 a.m., and at 9:30 p.m., with barely enough light to tell, he remained on guard. I did not see him off the nest platform ever. He did lie down for perhaps 15 minutes in late afternoon. At that point, both geese shut their eyes briefly now and then (second photo). I could not find information on hatching sequence, whether or not eggs unhatched for more than 12 hours after initial hatchings is normal or not. An egg can be seen directly under the goose in the photo below.
Canada Goose pair with eyes shut.
Here is a robin’s nest, an unusual nest because it seems to contain what appears to be deer hair, a lot of deer hair. I found it at Westwood Hills Nature Center in St. Louis Park. The Birds of North America monograph on American Robin describes the typical nest made by this species: an outer wall of dead grass and twigs lined with mud, the cup finished with dead grass. The mud is said to be from worm castings. Occasionally, white paper, feathers, rootlets, and moss are added, according to the authors. No mention is made of hair. There are many deer at Westwood Hills. The bird apparently made use of available materials. I once watched a robin building a nest, a conventional nest with grass and mud. The bird shaped the mud by rotating its body in the cup, using its breast and stomach to spread the mud on the nest walls. I wanted to see the inside of this nest to know if a more conventional approach was taken with cup construction.
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