CONFRONTING THE HABITAT FRAGMENTATION - HETEROGENEITY PARADOX: DOES ENHANCED PREY ACCESSIBILITY BUFFER FORAGING COSTS BY SPOTTED OWLS IN PATCHY LANDSCAPES?
|Ceeanna J Zulla; University of Wisconsin - Madison; firstname.lastname@example.org; H. Anu Kramer, Gavin M. Jones, John J. Keane, Kevin N. Roberts, Brian P. Dotters, Sarah C. Sawyer, Sheila A. Whitmore, William J. Berigan, R. J. Gutiérrez, M. Zachariah Peery|
Tension exists between two paradigms guiding species’ habitat and biodiversity conservation. One suggests that habitat fragmentation negatively affects individual species, while the other suggests that habitat heterogeneity can benefit individual species that rely on multiple habitat types. The California spotted owl (Strix occidentalis occidentalis) is an exemplar of the conundrum, where spotted owls benefit from larger patches of mature forests for both nesting and foraging purposes, but also benefit from younger forest and hardwood edges for foraging. Thus, we integrated high resolution GPS tagging, nest video monitoring, and remotely sensed habitat data to test three predictions regarding relative costs and benefits of heterogeneous landscapes. We predicted that owls with more heterogeneous habitat within their home ranges 1) travel farther distances, 2) deliver more prey to nests and 3) have higher reproductive rates. To test these predictions, we GPS-tagged 15 nesting male spotted owls and deployed cameras at their nests, allowing us to measure fine scale movements and prey delivery rates. We documented 358 prey deliveries, primarily of dusky-footed woodrats (41.5%) and Humboldt flying squirrels (40.2%). We examine the relationships between habitat heterogeneity and owl movement distances, prey delivery rates, and reproductive rates – and discuss their implications for Sierra Nevada forest management.