I prefer the term "poop pellet."? I have been photographing the swallows at the Edmonds marsh doing the same thing with the nest boxes.
?Bill Anderson; Edmonds, WA. USA

From: J Christian Kessler <1northraven at gmail.com>
To: Eric Ellingson <abriteway at hotmail.com>
Cc: tweeters <tweeters at u.washington.edu>; Whatcom Bird List <whatcombirds at lists.wwu.edu>
Sent: Saturday, July 8, 2017 10:33 AM
Subject: Re: [Tweeters] Bushtit nest behavior question. Diaper removal?

the technical term is fecal sack, but you got it exactly.? great photos.

Chris Kessler
Seattle