Common Grackle with food
Common Grackle with food
As the Maine Bird Atlas project progresses into late June, the number of confirmed breeding species found across the state has reached 160 (as of June 22). Locally, Knox County atlassers have confirmed 667 species, while Lincoln and Waldo counties have tallied 73 and 65 confirmations, respectively. Another 118 statewide species are currently in the “Probable” category and await further documentary efforts.

For their own security, birds become quite secretive during the early phases of the nesting season. Even species that lead normally bold and raucous lifestyles, such as our extroverted Blue Jays, are quietly restrained these days. Eventually though, clues of nesting activity become plainer as parents engage in feeding their growing nestlings.

I’ve discovered several nests of Yellow Warblers this spring. This common species nests close to waterways in thick, moist cover, often in stands of alders and low, brushy cover. I recently observed a lively nest as both scrambling parents alternately delivered insects to three nestlings at a roughly three- to five-minute rate. The Atlas breeding confirmation code for this particular behavior is FY = Feeding Young. The feeding maneuvers appeared coordinated and efficient. During several food passes, the parents removed whitish fecal sacs from the nest (Nature’s equivalent to the human diaper, the sacs sequester the liquid waste and keep the nest clean). The parents transport the sacs in their bill for disposal away from the nest location: confirming breeding code for that behavior would be FS = Carrying Fecal Sac.

Yellow Warblers are common victims of Brown-Headed Cowbirds that lay eggs in nests of unsuspecting hosts. After the hatching of the large cowbird chick, the smaller warbler parent must work vigorously to feed the demanding Baby Huey–sized fledgling. Occasionally, Yellow Warblers combat the cowbird’s parasitic ventures by adding a second or third story of nest material on top of the cowbird eggs. Resulting nests with as many as six stories have been found, with a cowbird egg in each layer! For us Atlassers, finding a cowbird with its host species is a bonus event, like spelling a double-combination word in Scrabble: we get confirmation credit for both species!

The high visibility of open marsh settings makes June nesting confirmations increasingly obvious as adult members feed their offspring. This includes two familiar marsh species, Common Grackle and Red-Winged Blackbird. It’s hard to ignore a territorial male Red-Winged perched atop his cattail empire. Studies indicate a strong degree of annual site fidelity once a male claims a territory. Being highly polygynous, the male blackbird assembles several mates within his nesting compound — 5 to 15 females in some cases. The females wind stringy plant materials around several upright stems to construct a platform of wet vegetation, leaves and decayed wood. Plastered mud forms a cup-like inner core to the finished nest.

Red-Wings are omnivorous, feeding primarily on plant materials and limited quantities of insects for much of the year. During the nesting season, dragonflies, damselflies, butterflies, moths, worms, spiders and flies provide a high-protein diet required for the fast-growing nestlings. Male Red-Wings breed at two years of age; females can breed at one year old.

On a recent morning excursion to Grassy Pond, I observed several adult Tree Swallows skimming the mirrored pond surfaces for moths and flying insects. The balletic, buoyant swallows raided groves of pond grasses, pausing momentarily to strip clinging insects from the upright grass stalks. In some instances, their catches were transported to nesting cavities in dead, waterlogged trees. The female Tree Swallow lines her nest with molted white body feathers of ducks and gulls, often placed so curved feather tips cover the eggs.