Why we do what we do

Starting in the late nineteen century bluebird populations across North America (Sialia sp.) began to decline. Expanding human development resulted in the loss of their natural habitat and continues today.  Simultaneously the steady removal of dead and dying trees, which provide cavities for nesting, represents a significant and steady threat to bluebirds and other cavity nesters.   Two introduced non-native species, the European Starling and House Sparrow are aggressive competitors for tree cavities.  As development expanded so did their populations. They continue to impact the breeding success of bluebirds and some other cavity nesting species in some regions.  However other natural predators such as outdoor cats, raccoons, rodents and native bird predators also impact bluebirds. Climate change is predicted to pose additional challenges for many birds.

To mitigate these pressures, we build and install (or replace) suitable nest boxes, maintain them in appropriate habitats, and monitor the birds’ breeding behavior in spring. As a result, bluebird populations have rebounded and appear stable.  This is an excellent example of citizen science in action across North America.

You can learn more about the Western Bluebird here.

Our sister program, the Cavity Conservation Initiative, enables us to work with tree care providers and property managers to promote the safe retention of dead trees as habitat for cavity nesters and other wildlife.


Bluebirds are losing their natural habitat. Photo by Melissa McMasters