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Photo by Tom Grey

Cavity Nesters Recovery Program

The Basics

CNRP involves many volunteers in Santa Clara County who establish and monitor nest box trails for cavity-nesting birds. During the breeding season, these boxes are checked weekly for parasitism, predation, number of eggs, nestlings, and number of young fledged. Then at the end of the nesting season, volunteers submit their results to us. We compile these results for the county and submit them to the statewide California Bluebird Recovery Program and other interested organizations.


Our program is immensely successful in helping native cavity-nesting species such as the Western Bluebird, Chestnut-backed Chickadee, Ash-throated Flycatcher, Violet-green Swallow and others. Cavity-nesting birds of prey such as Barn Owls, American Kestrels and Western Screech Owls also benefit.


This program is part of the California Bluebird Recovery Program, which is jointly sponsored by Audubon California and the North American Bluebird Society.


How You Can Get Involved

If you are interested in monitoring a nest box trail, contact our Programs Coordinator at for more information. In the meantime, we have gathered lots of references, information, and plans to make volunteering easy and successful.

Upcoming Events

Nest Box Monitor Training
No trainings currently scheduled. If you would like to learn more about the program and shadow a current nest box monitor, please email us at


Current Monitors - Submit Your Data!

Please take a moment to submit all of the data that you worked so hard to collect throughout the season. Data is collected and compiled by the California Bluebird Recovery Program so that cavity nesting bird populations across the state can be monitored. Links to data entry forms can be found below.

Your data can have an even greater impact if you also submit box-by-box information to Cornell's NestWatch Program. This data is used to study bird populations nationwide. Links to those forms are found below. 



Western Bluebirds, Ash-throated Flycatcher, Western Screech Owl

© Tom Grey


by Don Yoder


A down-to-earth conservation effort - the larger the better - can make a difference! Over the years, bluebirds have lived and reproduced in California. However, development in rural areas has destroyed much of their preferred habitat. Now their numbers are declining and we must take action to reverse the trend and prevent their total disappearance.


California is a state with wide variations in terrain, altitude and vegetation. There are many niches where bluebirds can be reestablished if cavities — nestboxes — are provided. Many people have not seen a bluebird in years in areas in which they used to be residents or frequent visitors.


There are many ways to help cavity-nesting species. While we particularly emphasize bluebird recovery, we welcome any cavity nester. All native species are a part of the natural scene and their preservation is of utmost importance to our own survival. We invite your inquiry and earnest participation.


We want to share the fun and excitement we experience when bluebird fledglings leave the nest to take their place among the trees and the grasslands.


As part of the state California Bluebird Recovery Program, a network of County Coordinators provides close contact with individuals who maintain their own nestbox trails. Questions and problems do arise and local help is usually available.


Participation by more people, the selection of good habitat, and the provision of proper boxes can make an impact on the survival rate and numbers of bluebirds. We are already seeing results throughout the State.


Our aims are to:

  • • Enlist current bluebirders and recruit others who will help reestablish bluebirds in their normal habitat
  • • Find typical habitat for the placement of nestboxes suitable for use by bluebirds
  • • Secure monitors to care for the boxes and keep systematic records of the development of young birds during the nesting season
  • • Record and analyze all annual summaries of nestbox records
  • • Provide a forum (newsletter) through which fellow trail operators can exchange information
  • • Secure help in solving problems encountered in the field