The average numbers of fledged young produced per pair during 1995, 1996, and 1997 in those colonies are in bold type.
The two study plots were checked regularly to determine date of egg laying, clutch size, hatching date, and number of fledged young.
In New York State alone - where an aggressive restoration program operates - the number of fledged young rose from fifteen in 1990 to seventy-one in 2000.
By mid-July, adults and recently fledged young form small, loose flocks.
A typical adult will breed several times over its long natural lifespan, but will only produce a small number of fledged chicks.
Egg quality was also assessed in terms of the probability that an egg would give rise to a fledged chick.
Newly fledged young have been found as early as May 21, suggesting a laying date of about March 20.
The male may provide support for up to 12 days after the young leave the nest, and the young often join other newly fledged young on communal roosts.
A nest was considered successful if at least one nestling was fledged .
Banding usually takes place during July-September (most bandings in this study occurred during August), and both young, fledged birds and adults are banded by capturing birds in bait traps.