Linking Reproductive Ecology and Habitat Use to Conservation

Dead Trees are Important (Martin et al. 2004)

Nest Predation is an Important Selective Force on Birds Higher in tropics and on open nesting birds –Parental behavior may be adjusted to reduce conspicuousness, guard nest, or thwart predators Introduction of exotic predators is devastating Tipping the balance in favor of certain native predators may be devastating –Increased edges and removal of top carnivores often leads to increases in generalist, mesopredators –LOVE YOUR LOCAL COYOTE

Does Habitat Use by Predators Matter? (Hutto 1985) ? Or ?

Our Basic Approach Mapping Predators Interpolating Predator Use of Study Area Relating Annual Productivity or Nest Success to Predator Use (Marzluff et al. 2007)

Relative Use of Area by American Crows

Relative Use of Area by Steller’s Jays

Relative Use of Area by Douglas Squirrels

Relative Use of Area by Townsend’s Chipmunks

Relative Use by All Surveyed Predators

Correlating Predators and Prey at 3 Scales Landscape Within Patch Forest patch Occurrence of Corvids 0 -2 / count 1 – 1.5 / count 0.25 – 1.5 / count

Scale-specific Responses to Crows Pearson Correlation Coefficient (r)

Pearson Correlation Coefficient (r) Some species are consistently found together Scale-specific Responses to Crows

Pearson Correlation Coefficient (r) Some species are consistently found apart Scale-specific Responses to Crows

Some Species Appear to Adjust Their Activity Within a Forest Patch to the Presence of Nest Predators

May adjust most to jays and squirrels because they are IN forest, and jays are incidental predators and small mammals are efficient, olfactory predators (Vigallon and Marzluff 2005; Bradley and Marzluff 2003)

Species May Vary in Their Exposure to Nest Predators Bewick’s Wrens, Dark-eyed Juncos, and Spotted Towhees exist with abundant predators --all permanent residents

Species May Vary in Their Exposure to Nest Predators Some Migrants live with Few Predators

Landscape Scale: Few Consequences of Living with Predators Correlations between total predator counts or counts of only corvids (subdivided and done various ways) were weak highest r = lowest p = 0.19 (1-tailed)

Conclusions Some songbirds may avoid nest predators within forest patches –At least we detect them less frequently during point counts in areas used heavily by predators Not avoidance during count (abundances during a count were often positively correlated), but avoidance of areas we determined independently to be used most frequently by predators Avoidance of jays and sciurids was stronger than avoidance of crows Living with jays and sciurids can reduce productivity which may reinforce the avoidance behavior we documented

Breeding May Occur When and Where We Don’t Expect It Hydrogen Isotopes Five neotropical migrants appear to breed in Western Mexico AFTER also breeding in more northern range (Yellow- billed Cuckoo, Cassin’s Vireo, Yellow-breasted Chat, Hooded Oriole, Orchard Oriole) Coastal Sinoloa and Baja get late summer/autumn rains that make it important areas for breeding that are in need of conservation (Rohwer et al. 2009)

Sibling Rivalry, Renesting and Captive Propagation Often the number of young that hatch is greater than the number that fledge –Cross foster or captive raise “extras” When a bird’s nest fails, they typically renest –Take eggs and double clutch to increase population (Cade and Jones 1993)

Literature Cade, T. J. and C. G. Jones Progress in restoration of the Mauritius Kestrel. Conservation Biology 7: Hutto, R. L Habitat selection by nonbreeding, migratory land birds. Pp in. M.L. Cody (ed.). Habitat Selection in Birds. Academic Press, San Diego. Martin, K., K. E. H. Aitken, and K. L.Wiebe Nest sites and nest webs for cavity-nesting communities in interior British Columbia, Canada: nest characteristics and niche partitioning. Condor 106:5-19. Marzluff, J. M., Withey, J. C., Whittaker, K. A., Oleyar, M. D., Unfried, T. M., Rullman, S. and J. DeLap Consequences of habitat utilization by nest predators and breeding songbirds across multiple scales in an urbanizing landscape. Condor 109: Rohwer, S., K. A. Hobson, and V. G. Rohwer Migratory double breeding in Neotropical migrant birds. Proc. Natl. Acad. Sci. 106: