|6/24/2015 3:53:00 PM|
Care and Feeding-
by Don ReimerSeen any baby birds in your neighborhood? For some species, the nesting season has reached the halfway point as fledgling birds are leaving the nest to trail their parents through the woodlands. Many ducks, geese and Pied-Billed Grebes have produced their yearly broods. Squawking raven chicks now perch near their vacated stick nests, yelling to be fed. Contingents of mocha-toned European Starlings are noisily begging from parents. Song Sparrow pairs scold anyone that enters the vicinity of their active nests. I observed an adult Red-Breasted Nuthatch cramming insects down its fledgling's throat; a fast learner, the fledgling immediately flew to my feeding station for a sunflower seed snack.
Currently a pair of Eastern Phoebes is raising their quadruple family of chicks out back. The two parents split up the feeding duties, taking charge of two chicks apiece and leading them around the rim of my yard. With food now being so plentiful, nourishing morsels are delivered every few minutes. Although the Phoebe's staple diet consists of flying insects, they are mid-April migrants to Maine. The species' distinctive tail-bobbing action helps us to clinch the bird's identification.
Any shelf-like projection, such as undersides of bridges and trestles, cliff sides, eaves and window ledges, makes for a desirable Phoebe nest location. The first recorded bird banding record in North America is attributed to John James Audubon in the early 1800s when, as a curious teenager, he fastened silver treads around the legs of nestling Phoebes. The following spring Audubon confirmed that the birds had returned to the same locality.
Like most small songbirds, Phoebe hatchlings are altricial birds. This means they are blind and naked when hatched, in an undeveloped state that requires care and feeding from parents. The 10- to 14-day incubation period is relatively brief and egg sizes are proportionally small in relation to the female's body size.
By contrast, Killdeer produce precocial young. This vociferous ground nester excavates a shallow nesting scrape in gravelly soil in open habitat. Males may create several scrapes and then await the female's final selection of the actual nest. Precocial eggs are relatively large and packed with an extra supply of nutrients to allow fuller development of the embryo during incubation time. Chicken-like birds, such as Wild Turkeys and Ruffed Grouse, are other examples of precocial species.
The Killdeer's 24- to 26-day incubation period does not commence until the fourth and final egg is laid, increasing the odds that the chicks will hatch on the same day. The resulting Killdeer chicks are fully clothed with downy feathers and are quickly afoot to search independently for food. The chicks' lanky, muscular legs are especially evident when they first hatch.
Instant mobility is a crucial survival factor for all ground-dwelling hatchlings. For about a month, the Killdeer parents will brood the chicks at night to keep them warm and engage in elaborate, "broken wing" displays to distract predators away from the flightless youngsters.
Food resources are less predictable for oceangoing birds. Out in the pelagic zones, tiny fish and other marine organisms may shift in their location or timing, causing adult birds to fly longer distances to obtain food. Sometimes a specific food type is not available and pelagic chicks are forced to consume other prey that doesn't suit their dietary needs or, in some cases, fit well down their digestive tract.
Article Comment Submission Form