To the editor:

I appreciate Shoreline reader Carla Lindquist's empathy in her response to the story about the 12 osprey chicks translocated from Westport to help restore the endangered population in Illinois. This speaks to her care and concern, which are important for the protection of our wildlife neighbors.

Among birds, ospreys are long-lived, reaching up to 25 years. A successful female and her mate may attend to 50 offspring throughout their life. However, they care for their young for only about 18 weeks: Five weeks of incubating eggs, nine weeks of caring for chicks in the nest, and another four weeks of providing fish to fledglings.

The division of labor at the nest assigns fishing to the male while the female tears apart what he delivers and distributes it among the chicks. The female vacates the area soon after the chicks begin to fly. The male remains to provide fish to the young while they develop their flight and fishing skills. The male then departs on his migratory journey, leaving the young to fend for themselves. The young who survive will strengthen for several more weeks before venturing on a solo migration to southern climates. Upon their first northbound migration, 18 months later, male osprey may return to the region where they hatched but females more often take up residence farther away. In their lifetime, neither are likely to ever see their parents again or know any of their (49!) siblings. 

Mortality — from exposure, starvation, predation, competition, accident, and more — is common. Three out of five osprey chicks will not survive their first full year. An estimated 15 to 20 percent of juveniles starve in the nest, often because of intense sibling competition. When 12 chicks were translocated to Illinois, there was more food to go around for the siblings in Westport and less pressure on the male to provide it, leaving the remaining chicks more likely to survive and succeed in the migration to come.

Meanwhile, the chicks translocated to Illinois were provided fish steaks every day by their human caretakers. After the chicks fledged, a wild local osprey also delivered fish to them (an adult male will readily deliver fish to juveniles other than his own).

When it is their time to migrate, these birds will encounter many of the same hazards as their East Coast siblings, but they are likely to be stronger and better fed as they face these challenges. With luck and a little human assistance, some of this year's cohort of 140-plus Westport River fledglings will enjoy full adulthood and many migrations, whether they return to New England or to Illinois.

Gina Purtell

Ms. Purtell is program manager of community science and coastal resilience for Mass Audubon South East.