Thanks to our dedicated volunteers and support from Maryland Ornithological Society, Hawk Mountain, and the National Fish and Wildlife Foundation, we have expanded nest box installation and monitoring efforts this year. We added 19 American Barn Owl boxes and 59 American Kestrel boxes. Both species depend on cavities, which are increasingly scarce in modern landscapes. By installing and monitoring these nest boxes, we are creating real opportunities for recovery while building the long-term dataset needed to guide our conservation work.
Raising a barn owl nest box for installation on the pole. Photo by Julie Maynard.
Landowners and volunteers are integral to our work. Landowners maintain the habitat these birds need and support the use of nest boxes on their farms. Many landowners also monitor their own boxes, letting the FRP team know when a pair has begun nesting. For landowners unable to monitor their boxes, our tireless volunteers help fill the gap. They provide updates throughout the season, clean and maintain the boxes over the winter, and—maybe the most exciting part—let our banders know when the chicks are ready. Our volunteers, landowners, and their families often join us during banding, creating lasting connections and memories with these farmland raptors.
Barn Owl Occupancy and Success Rates
We checked 110 barn owl boxes in 2025, and about one-third were occupied. A box is occupied when the raptors are actively using the box, and this 30% occupancy rate is nearly the same as in past years. About two-thirds of nests succeeded, while 19% failed (the outcome of the remaining nests is unclear). We banded 113 barn owls this year (91 chicks and 22 adults), compared to 134 last year (104 chicks and 30 adults). Occupancy has held steady from 2021-2025 (around 30%), but this year’s nest success rate was the lowest across that same period. From 2021 to 2023, 75-80% of nests succeeded; that dropped to 71% in 2024 and 68% this year.
Figure 1. Barn owl nest box occupancy rates, Maryland Farmland Raptor Program, 2021-2025
These statewide numbers, however, may mask important regional differences. Barn owl boxes in the Patuxent River Valley have historically shown lower occupancy and success compared to other parts of Maryland, and rates there now appear to be dropping further. Because these owls hunt the marsh, it is likely that sea level rise is altering marsh structure in ways that reduce prey availability. Areas that were previously drier are now wetter, making them less suitable for prey species like meadow voles and marsh rice rats to venture into the marsh. At the same time, increased nest box efforts in central Maryland, where occupancy and success rates have stayed steady, may make statewide results look more stable than they actually are regionally. Given the limited historical data from central Maryland and the rapid decline observed in the Patuxent River Valley, it is too early to draw firm conclusions.
Still, barn owls continue to make reliable use of nest boxes in Maryland, even as annual success rates fluctuate. Long-term monitoring will show whether barn owl productivity rebounds, and help us determine if additional conservation actions are needed.
Figure 2. Barn owl successful nesting rates, Maryland Farmland Raptor Program, 2021-2025
Avian Influenza Sample Results
During the course of our banding efforts, we also sampled seven barn owls for Highly Pathogenic Avian Influenza (HPAI) in partnership with USGS. Results are back for four of the owls, all of which tested negative. HPAI is a contagious virus that causes high mortality in poultry and sometimes affects wild birds, though many wild species can carry the virus without showing symptoms. With concerns about HPAI growing, this work is especially timely. These results will help us keep farmers informed about the risks that farmland raptors may, or may not, pose to their operations.
Kestrel Occupancy and Success Rates
Inspecting the wing feather color of an American Kestrel chick to determine its sex. Photo by Margaret Poethig.
This season also marked the start of a more intensive kestrel monitoring program. Incredibly, we have installed 64 boxes throughout central Maryland in the last two years, and over a quarter of those boxes were occupied this year. Even better, at least two-thirds of those nests successfully produced young. We banded 79 chicks this year. Many of the kestrel boxes are still newly installed, and our expanding monitoring efforts will help build the long-term dataset needed to track trends moving forward.
These early results are encouraging and show that kestrels are taking to the boxes. Through continued monitoring, we expect to better understand occupancy and nest success trends in the future.
Building a Foundation for Healthy Raptor Populations
As we continue to increase our nest box installation and monitoring work, the data we collect will show us where nest boxes are most effective and when additional management actions may be needed. With the continued support of landowners, volunteers, and partners, we are building the foundation for healthier populations of barn owls and kestrels across Maryland.