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No abstract

Successful reintroductions of endangered species rely on comprehensive knowledge of habitat requirements across spatial and temporal scales. To inform designs of reintroduction programs, we studied habitat selection of the federally endangered Sierra Nevada yellow‐legged frog (Rana sierrae) in streams in its northern range. We quantified multi‐scale habitat use across diverse streams, habitat types within streams, and seasonal flows. In one intermittent stream, we compared habitat selection between wild and captive‐reared frogs that were released as a population augmentation. We analyzed habitat selection of seasonal habitat unit types (e.g., pool, riffle, cascades) and dimensions, and microhabitat hydrology and cover. R. sierrae appeared able to meet its ecological requirements in a variety of habitats. Study streams ranged from third‐order perennial streams to first‐order intermittent headwater creeks. Perennial streams retained a variety of habitats across flows whereas intermittent streams dried to just a few pools. Frogs used all seasonal habitat types but selected deeper pools most often relative to available habitats in intermittent streams and selected riffles or showed no preference in perennial streams. Frogs avoided fast deep‐water microhabitats, but, otherwise, preferred flowing water or deeper water without flow. Our results suggest that diverse streams can be considered candidates for reintroductions. Within intermittent streams, deeper perennial pools may provide more stable release sites, whereas non‐pool habitats may be safer in perennial streams with fish. Importantly, captive‐reared frogs selected similar habitats as wild frogs, suggesting that captivity does not alter habitat selection behaviors post‐release and that reintroduction designs for this species can be based on wild frog preferences. By improving our understanding of how habitat use varies among different types of streams and differs seasonally in response to changing habitat conditions, our results inform the design of effective reintroduction programs for frogs in streams.

Habitat use by federally threatened California Red-Legged Frogs (CRLF; Rana draytonii) is incompletely understood. I captured, PIT-tagged, and radio-tracked CRLFs (n = 20) at Waddell Creek, Santa Cruz County, from July-December 2012. Limited tracking for movements was also conducted in 2013. Frogs were clumped in deep, complex habitats along the stream within 2 km of breeding ponds near the stream mouth, but most adults were concentrated in the lagoon. Marked and tracked frogs had very small summer home ranges, and most returned to the same home range after breeding. Frogs tended to use good aquatic (e.g., wood, undercut banks, dense willows) and bank cover (e.g., ground vegetation, wood) at all times but used open habitats more at night than during the day. Visual night surveys were biased against cryptic frogs compared to radio-tracking results. Early fall rains increased upland habitat use, but later heavy winter rains were needed to trigger migration to breeding sites and subsequent breeding. Site-specific studies using radio-tracking are needed to design protections for breeding, migration, and nonbreeding habitats. v ACKNOWLEDGEMENTS This work is dedicated to my family and their unwavering support, but especially to my mother, Carol, who intimately understands what it's like to have a son who spends most of his time dreaming. Even during my own brief moments of self-doubt, she never once doubted that I would complete my thesis. She is living proof that one woman, through her joyful love of life and family, and the calm grace of strength devoid of hate, can inspire all who know her with the nobility of the human spirit. Regrettably, I am uncertain in my ability to truly convey just how appreciative I am of Jerry Smith, a man of inspirational intellect, integrity, wit, and generosity… and a friend who is always there for me. Much of the biologist I am today is largely a direct result of his careful instruction and boundless patience. I transferred to San José State University in 2008, and I will always think fondly of my time as a student. I thank all the talented professors for unabashedly fueling my curiosity of the natural world, and for answering all my questions, no matter how silly, in this pursuit. I especially thank Stephanie Trewhitt, Paula Messina, Luis Bonachea, and Carole Ann Foster for their guidance and assistance throughout this project, but