At the Project:
Most nests are empty now, although boxes where replacements or takeovers
occurred may still contain nestlings .  A few scruffy adults still hang around sunning
and preening, and you may notice the beginning stages of molt, the replacement of
their feathers.  In Tree Swallows adult molt usually starts by early July.  As they fly
overhead look for notches in the trailing edges of adults' wings and tails where their
first flight feathers have been lost.   

Since some of your former nestlings, now fully independent juveniles, may linger
around the project for a week or two longer if the foraging is good, this is the best
time to check them out.
















Concepts:
How do you tell juvenile Tree Swallows from adults?
  • Juveniles have sooty gray-brown upper bodies, wings, and tails, without any
    trace of blue or green.
  • A few juvenile Tree Swallows may show a faint breast band (see below).  















  • Don't mistake these juvenile Tree Swallows for Bank Swallows, whose breast
    band is much darker and more solid.  Compare the well-defined band on the
    Bank Swallow below left to the faint one on the Tree Swallow above.  The bird
    below right is a more typical, bandless juvenile Tree Swallow.















  • Juveniles weigh about the same as adults but their shorter, rounder-tipped
    wings and tails make them appear smaller and chunkier.
  • Juvenile flight is a bit slower, weaker, and more "fluttery" than adults'.
  • If viewed up close some juveniles may still show traces of yellow flanges at the
    corners of their mouths, as in the photo below by Len Blumin.
















When will juveniles get their adult plumage?
  • Juvenile molt to adult plumage begins a few weeks after fledging.
  • Molt is a gradual process, extending over several months.
  • Surviving juveniles will complete feather replacement by late autumn.
  • Juvenile males will acquire the blue-green iridescent upper body possessed by
    all after-hatch-year (AHY) males.
  • Juvenile females will acquire the brownish-green upper body plumage that
    distinguishes second-year (SY) females from older ASY females.

While juveniles hang around, what are they doing?
  • Juveniles join adults as they forage for food over fields and wetlands.
  • Some may beg at passing adults, trying to get a free meal.
  • When not foraging they often perch in groups on wires and trees, resting and
    preening their feathers.












  • They may land and sun themselves on roads, beaches, and other warm
    surfaces.
  • Juveniles often approach nest boxes, fluttering around, perching on, and
    even entering them, especially if they still contain living nestlings.
















Why do juveniles congregate at boxes that still contain nestlings?
  • We aren't sure.
  • It's been suggested they're "scouting" potential nest sites for next year, but
    there's no evidence supporting this.
  • Some may be trying to mooch a free meal from resident adults.
















  • They definitely are not "helping out".  Their presence may actually interfere
    with parents trying to feed nestlings in late nests.  Note the juvenile blocking
    the hole in the photos above and below, preventing an adult from delivering
    food to its own small young inside.
















Question for the next Topic:  After Nesting.
  • What happens after nesting is complete?
  • Where will all your the swallows go and what do they do?









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Independent Juveniles
Learn About Birds at Tree Swallow Nest Box Projects