Birds, the most mobile and migratory of animals, are at their most vulnerable while nesting.
Right now the breeding season is in full swing for Cape and Island bird life. Some species - the Neotropical migrants that only have one brood - are close to finishing their nesting chores, while others like Mourning Doves and American Robins are well into round two.
Tied to one spot for this critical period, not only are the adults easy targets for predators, but the eggs and nestlings have no defense. However, over the course of time and constant evolution, the birds that nest successfully are doing something right and this gets passed on to the succeeding generation. Which is why bird nests are so hard to find.
When a predator like a cat or a snake threatens a bird’s nest with an adult bird incubating or brooding the young, the adult birds remain until they either must flee or be eaten. The flight response is the proper one and the adult bird can live to nest another day and in another season. They may attempt to lure the predator away feigning injury and often put up a stiff defense, especially in the case of crows or Blue Jays, to drive off much larger animals.
Nests are placed to be as inaccessible to four-legged predators as possible. Some species defense from winged predators comes by nesting colonially, mobbing would-be predators, and driving them off. At any rate, the moment the young can leave the nest and become mobile, the parent birds get them away from the nest site. Instantly, they are safer from terrestrial predators that no longer have scent clues and a fixed target to hunt.
A phenomenon that has been increasingly documented and debated is the so-called post-breeding dispersal, exhibited by many species of herons, terns, raptors and sub-adult birds of many species. Our region is a very good place to find southern species that have wandered or purposely chosen to venture far north of their species normal or expected range. Maybe it is normal for them to occur, late in the breeding season, mid to late summer, in some or most years. We learn more every year.
