Protecting and Creating Nesting Habitats to Boost American Kestrel Populations
We are excited to see that our efforts in supporting expanding American kestrel populations in the Mount Diablo area have been fruitful.
For many years, Save Mount Diablo volunteers and staff members have been installing and maintaining nest boxes around the mountain, and it’s great to see that many of these have been utilized as nesting habitats for North America’s smallest falcon.
American kestrel. Photo by Rick Cameron | CC BY-NC-ND
Kestrels are cavity nesters, they don’t typically build large stick nests or incubate eggs on rock scrapes, like eagles and peregrines. Instead, they find hollows in trees and at times buildings to lay their eggs and raise their clutch of young.
Populations of these fantastic raptors have been on the decline for more than 50 years in North America, and much of that decline can be attributed to habitat loss, like the removal of large trees with cavities, because of development.
Building and installing nest boxes is an easy way to create nesting habitat for these birds, and promote population increases, and the cool thing is, they seem to like these boxes.
Kestrel box in Curry Canyon. Photo by Floyd McCluhan
There are 37 nest boxes that we’ve installed around the mountain, and of the seven that we monitor closely, each of those boxes have fledged four to five young birds annually for the past five years of close monitoring.
This is really exciting news!
It shows that protecting and creating nesting habitats directly around the mountain is helpful in boosting populations, clearly linking the success of our conservation efforts and the importance of a positive interaction between human beings and open spaces.
How do we know that these boxes have been so successful?
Well, many years ago Brian Smith of The Kestrel Campaign and I installed game cameras on numerous boxes that had shown themselves to be productive.
Over the years we have included a couple more cameras on successful boxes so we can observe behaviors, prey delivery diversity, prey delivery rates of both parents, and when birds fledge.
An American kestrel feeds its young in one of our kestrel boxes. Photo by Save Mount Diablo wildlife camera
The wildlife cameras allow us to gather data without being invasive and causing stress to these wonderful birds while they are incubating and growing.
At the end of the nesting season, we gather memory cards and start crunching through the tens of thousands of images that have been collected during the season.
This year, we will be installing an additional 12 cameras on 12 boxes that we have not been monitoring as closely.
The additional cameras will help us to understand more about how kestrels are utilizing nesting habitat on a larger scale around the mountain, bringing our total number of boxes we observe to 19.
An American kestrel feeds its young in one of our kestrel boxes. Photo by Save Mount Diablo wildlife camera
This is in part because in fall of 2024 we received a grant from the Contra Costa County Department of Conservation and Development to explore our observations further, potentially affecting the future of project planning countywide.
We hope to discover more American kestrel populations increasing around the mountain, through our expanded monitoring efforts. Stay tuned!
If you would like information on installing kestrel boxes at your home or surrounding open space, please reach out to Sean Burke at sburke@savemountdiablo.org.
