First-of-its-Kind Study Sheds Light on Forest Thinning Impacts on Pinyon Jays

Though the pinyon jay population continues to decline at alarming rates, until now the threats facing it remained largely under-researched.  Defenders of Wildlife, along with the U.S. National Forest Service and Santa Fe County, have released a three-year research project evaluating impacts of forest thinning on bird species reliant on piñon pines and juniper trees.  

The study, published in the peer-reviewed scientific journal Avian Conservation and Ecology, is the first to record statistically significant negative impacts of forest thinning on pinyon jays — a species Defenders petitioned for protection under the Endangered Species Act in 2022. As a result of the research, Defenders recommends land managers reevaluate thinning in piñon-juniper woodlands, especially those home to pinyon jays and other imperiled species.  

“While we’ve known that loss of habitat and, in particular, woodland thinning has an impact on the decline of pinyon jays, now we know more critically the severity and details of this impact,” said Peggy Darr, Defenders of Wildlife New Mexico representative. “This research opens new doors for better-informed pinyon jay conservation. Defenders of Wildlife looks forward to continued collaboration with our partners to incorporate the results of this research into piñon-juniper land management.”

The study, “Thinning Effects and Underlying Pathways for Birds of Conservation Concern in New Mexico Piñon-Juniper Woodlands,” found that thinning in these ecosystems has negative effects on bird species of high and moderate conservation concern, as well as five priority imperiled species identified by the New Mexico Avian Conservation Partners:  

• Pinyon jay (Gymnorhinus cyanocephalus)
• Woodhouse’s scrub-jay (Aphelocoma woodhouseii)
• Juniper titmouse (Baeolophus ridgwayi)
• Virginia’s warbler (Leiothlypis virginae)
• Black-throated gray warbler (Setophaga nigrescens)

Piñon-juniper woodlands span across the American Southwest and Great Basin and are essential to the survival of many species. Thinning piñon-juniper woodlands commonly occurs throughout the pinyon jay range for the purpose of fire hazard reduction and livestock grazing.