Monitoring for Nest Box Successes


"We are proud participants in the Farmland Flyways initiative, which encourages farmers and ranchers to provide habitat and nest boxes for beneficial wild birds." -Little Paradise Farm (click to see a video of their bluebird nestlings)

By Nick Filannino, WFA GrizzlyCorps Fellow

Wild Farm Alliance and our partners monitored 174 songbird nest boxes last year on farms across the Central Coast of California. Most of the boxes were checked while cleaning them out in the fall or winter. We recently analyzed the data and of the 174 boxes, 127 were occupied during the breeding season by songbirds, giving us a 73% occupancy rate! We determined seven different species were using our boxes.


Out of 129 nests we found:

  • 64 Western Bluebird nests
  • 44  Tree or Violet-Green Swallow nests
  • 10 Chestnut-backed Chickadee nests
  • 7 Oak Titmouse nests
  • 1 of Ash-throated Flycatcher nest
  • 1 of Bewick’s Wren nest
  • 2 unidentified nests

For the keen reader, let me answer a few questions!

  1. First you might ask “Why were 127 boxes occupied, but there were 129 nests… How is it possible?!” Every season we find that boxes are used for more than one brood throughout the season. For example a Bluebird might raise a clutch of chicks from late-March until May, raise a second clutch from Late-May until Mid-July, and then possibly a third after that before the fall. Sometimes we find that the same species will use a box during a season for multiple clutches, but other times we find that a different species will use a box after the first species and build a new nest right on top of the old nest! We saw twice this year a Bluebird nest with a Swallow nest stacked upon it. So that’s where we get the two “extra” nests from!
  2. Your next question might be “Why do you group Tree and Violet-Green Swallows together?" We group them together because the nests are indistinguishable from each other, and they fill a very similar ecological niche!
  3. You’re also probably wondering how we can tell the difference between all the different nests we find? There are easy to spot identifiers that can tell you what species made the nest you’re looking at. You too can learn how to tell the difference between nests you find by using our “What and Where Beneficial Songbirds Eat and Nest” Chart available on our website!
  4. Finally, you might be asking "How can I share information about my nest boxes as part of the Farmland Flyways Initiative?" Keep records of what you find when monitoring your boxes and share the information with Wild Farm Alliance by emailing us at [email protected]. We will add you to our Farmland Flyways Map (see the Farmland Flyway Trail tab).