Piñon-juniper fuels reduction treatment impacts pinyon jay nesting habitat

Abstract

Across multiple continents, mechanical thinning of forests and woodlands is an increasingly common management approach to reduce potential fire risks or improve ecological condition. Thinning programs designed to reduce fire risk typically place priority on human needs with little consideration of impacts to wildlife. We report on the results of a fuels reduction treatment at a traditional pinyon jay (Gymnorhinus cyanocephalus) nesting colony in persistent piñon-juniper woodlands in New Mexico, USA. The treatment affected 21% of the traditional colony site, reducing tree density in treated areas from a mean of 1893 trees per hectare to a mean of 248 trees per hectare, an 87% reduction. Generalized linear mixed models indicated tree density and basal area were significantly greater at pinyon jay nests than in untreated areas and greater in untreated areas than treated areas. Tree diameter was greater in treated areas than in untreated areas and at nests, indicating that treatments retained larger trees. Areas treated in 2018 included 11 nests active in 2017. No nests found in 2018 were within the treated areas, with tests indicating that pinyon jays avoided nesting in treated areas. Although the treatment rendered previously suitable pinyon jay nesting habitat unsuitable, pinyon jays continued to nest near treated areas. While treatments should be planned to avoid direct losses of habitat, pinyon jays may be tolerant of treatments near traditional nesting areas in the short run, suggesting that slightly altering the location of treatments might allow them to occur without impacting traditional nesting areas. Longer-term monitoring across additional areas will help improve understanding of the impacts of thinning on wildlife and their habitat.