Graduation Date
Fall 2017
Document Type
Thesis
Program
Master of Science degree with a major in Natural Resources, option Wildlife
Committee Chair Name
Dr. Daniel Barton
Committee Chair Affiliation
HSU Faculty or Staff
Second Committee Member Name
Dr. Brian Hudgens
Second Committee Member Affiliation
HSU Faculty or Staff
Third Committee Member Name
Dr. Matthew Johnson
Third Committee Member Affiliation
HSU Faculty or Staff
Keywords
Tadpoles, Frogs, Eggs, Survival, Canopy, Population, Climate
Subject Categories
Wildlife
Abstract
Many amphibian species are in decline due to habitat loss and changing climates. Understanding how habitat characteristics and climate influence vital rates, and if they act in concert or in opposition can inform management decisions. This study investigated the potential interaction of canopy cover and climate on early stage vital rates of northern red-legged frogs. Demographic data were collected from sample populations in experimental canopy cover treatments across a latitudinal distribution. Rearing cages were used to estimate hatch success, and mark-recapture surveys to estimate tadpole survival. Ambient air temperature was used as an index of climate because it is easily relatable to the effects of climate change and collected at fine scales without specialized equipment. Estimates from field data, along with published accounts were used in a matrix modeling analysis to evaluate if tadpole survival impacted population growth rates.
Egg hatch success did not differ between canopy treatments or among sites. Canopy cover did affect tadpole survival rates, but not tadpole development time. The effect of canopy over on tadpole survival varied depending on which population was being evaluated. There was no evidence that the effect of canopy cover on tadpole survival was dependent on air temperature. Tadpole survival rates did impact population growth rates.
This research shows that the effect of canopy cover on early stage vital rates for this species is variable between populations, but not due to differences in average air temperatures. For some populations the effect of canopy cover on tadpole survival was large enough to change projected population growth rates from stable to decreases of 30%. These results demonstrate that manipulating canopy cover can influence tadpole survival sufficiently enough to alter population trajectories. However, the variable effects of canopy cover on vital rates suggest a universal management strategy through canopy cover manipulation will not have equal impacts across populations.
Citation Style
Journal of Wildlife Managment
Recommended Citation
McHarry, Kecly, "The influence of canopy cover and climate on early life-stage vital rates for northern Red-legged frogs (Rana aurora), and the implications for population growth rates" (2017). Cal Poly Humboldt theses and projects. 87.
https://digitalcommons.humboldt.edu/etd/87