Tall, heterogeneous forests improve prey capture, delivery to nestlings, and reproductive success for Spotted Owls in southern California

• Published in: Ornithological Applications 2023-03, Vol.125 (1), p.1-12
• Main Authors: Wilkinson, Zachary A., Kramer, H. Anu, Jones, Gavin M., Zulla, Ceeanna J., McGinn, Kate, Barry, Josh M., Sawyer, Sarah C., Tanner, Richard, Gutiérrez, R. J., Keane, John J., Peery, M. Zachariah
• Format: Article
• Language: English
• Subjects: Animal reproduction; Breeding success; Canopies; captura de presas; Chaparral; Conservation; Ecosystem resilience; Forest management; Forests; Global positioning systems; GPS; habitat selection; Heterogeneity; Neotoma; Nests; Ornithology; Owls; Predator-prey interactions; Predators; Prey; prey capture; rata de bosque; reproducción; Reproduction; RESEARCH ARTICLE; selección de hábitat; southern California; Strigidae; Strix occidentalis; Strix occidentalis occidentalis; Structure-function relationships; sur de California; Vegetation; Wildlife conservation; woodrat
• ISSN: 0010-5422; 2732-4621
• DOI: 10.1093/ornithapp/duac048

Predator–prey interactions can be profoundly influenced by vegetation conditions, particularly when predator and prey prefer different habitats. Although such interactions have proven challenging to study for small and cryptic predators, recent methodological advances substantially improve opportunities for understanding how vegetation influences prey acquisition and strengthen conservation planning for this group. The California Spotted Owl (Strix occidentalis occidentalis) is well known as an old-forest species of conservation concern, but whose primary prey in many regions—woodrats (Neotoma spp.)—occurs in a broad range of vegetation conditions. Here, we used high-resolution GPS tracking coupled with nest video monitoring to test the hypothesis that prey capture rates vary as a function of vegetation structure and heterogeneity, with emergent, reproductive consequences for Spotted Owls in Southern California. Foraging owls were more successful capturing prey, including woodrats, in taller multilayered forests, in areas with higher heterogeneity in vegetation types, and near forest-chapparal edges. Consistent with these findings, Spotted Owls delivered prey items more frequently to nests in territories with greater heterogeneity in vegetation types and delivered prey biomass at a higher rate in territories with more forest-chaparral edge. Spotted Owls had higher reproductive success in territories with higher mean canopy cover, taller trees, and more shrubby vegetation. Collectively, our results provide additional and compelling evidence that a mosaic of large tree forest with complex canopy and shrubby vegetation increases access to prey with potential reproductive benefits to Spotted Owls in landscapes where woodrats are a primary prey item. We suggest that forest management activities that enhance forest structure and vegetation heterogeneity could help curb declining Spotted Owl populations while promoting resilient ecosystems in some regions. How to Cite Wilkinson, Z. A., H. A. Kramer, G. M. Jones, C. J. Zulla, K. McGinn, J. M. Barry, S. C. Sawyer, R. Tanner, R. J. Gutiérrez, J. J. Keane, and M. Z. Peery (2023). Tall, heterogenous forests improve prey capture, delivery to nestlings, and reproductive success for Spotted Owls in southern California. Ornithological Applications 125:duac048. LAY SUMMARY Identifying where prey is captured can help understand high-quality hunting habitat for predators but is very difficult to do for small cryptic predator