Guide

Go seeBirds

Cornell NestWatch bird boxes along Allens Pond's accessible trail

May to July

Bird boxes throughout the fields beside the Allens Pond All Persons Trail are part of Cornell's NestWatch community science project, and a replica box at one stop opens to show a model bluebird and egg. Tree swallows and eastern bluebirds have both used them, and tree swallows are acrobatic insect hunters with bright, iridescent backs and white bellies.

Why this time of year

Mass Audubon's atlas account says tree swallow nest building peaks in the last week of April and early May, nestlings have been reported from early June to late July, and most young fledge from late June to mid-July. The sanctuary's guide says staff and volunteers check the boxes through spring and summer.

How to notice it

  1. Walk the All Persons Trail from the Stone Barn entrance at Allens Pond Wildlife Sanctuary to the field stop with the replica bird box, then scan the real boxes in the fields for a bird perched on top or ducking into the hole.
  2. Watch the air over the field. The trail guide calls tree swallows amazing acrobatic flyers, and they hunt insects.
  3. Listen for a perched swallow's liquid twitter, and for a bluebird's soft 'tur-a-wee' call.
  4. Lift the doorknob panel on the replica box at the stop to see a model bluebird and egg inside, and watch the real boxes from the trail, since they are part of a monitored study.

Try this with kids: Pick one nest box and count how many times a bird flies in or out in two minutes.

Phrase to know: “To fledge” is to leave the nest for the first time.

Sources

  • massaudubon.orgMass Audubon, Allens Pond accessibility page (landowner, primary): 'Trail surfacing consists of a combination of mixed stone, a grass paving material, and some boardwalks'; 'Starting off on a level gravel path'; audio stops '5 - Field Habitat' and '6 - Managing Fields.' (read 2026-11-10)
  • massaudubon.orgAllens Pond All Persons Trail audio tour booklet (landowner, primary; PDF dated 2022-06-28): replica nest box with doorknob panel and a resin Eastern Bluebird and egg; 'Similar bird boxes are found all throughout the nearby fields'; 'a community science project sponsored by Cornell University called Project NestWatch'; 'During the spring and summer, Mass Audubon staff and volunteers monitor these bird boxes'; boxes 'used by Bluebirds, House Wrens, Tree Swallows'; tree swallows 'amazing acrobatic flyers with bright iridescent coloration on their backs and a white belly'; song 'a liquid twitter'; bluebird call 'tur-a-wee.' (read 2026-11-10)
  • massaudubon.orgMass Audubon Breeding Bird Atlas 1 account, Tree Swallow (data 1975-1979): 'Nest building activity reaches its peak during the last week of April and early May'; 'Nestlings have been reported in Massachusetts from June 5 to July 23'; 'Most young fledge in the Commonwealth from late June to mid-July'; 'readily adapted to nesting boxes.' (read 2026-11-10)

Checked against these sources on November 10, 2026.

In the guide for May, June, July

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