Endangered Species Management
flatwoods salamander recovery
My PhD dissertation at Virginia Tech focussed on conducting a population viability analysis of flatwoods salamanders. Using information on growth and survival obtained through drift fence monitoring, I constructed integral projection models (IPMs) to estimate extinction probabilities under different management scenarios. To build the IPM I developed growth curves, the first of their kind, that jointly model amphibian growth before and after metamorphosis, and survival curves that account for seasonal differences in mortality. Scaling up from individual populations to the landscape level, I developed one of the first spatially-explicit metapopulation models for a pond-breeding amphibian, and investigated the importance of detectibility and genetic diversity in the context of future reintroduction efforts. Ultimately, this body of work was used to aid flatwoods salamander recovery.
Publications
Martin, A. K., G. C. Brooks, H. C. Chandler, K. C. Jones, B. K. Rincon, and C. A. Haas. Tracking Reticulated Flatwoods Salamander (Ambystoma bishopi) recovery in response to habitat restoration and translocations. in review
Chandler, H. C., N. M. Caruso, G. C. Brooks, and C. A. Haas. 2024. Wetland hydrology, not altered phenology, challenges Reticulated Flatwoods Salamander (Ambystoma bishopi) management under future climate change. Ichthyology and Herpetology 112:531-543. link
Brooks, G. C., H. C. Chandler, D. Z. Childs, Y. Jiao, and C. A. Haas. 2024. Predicting the population viability of an endangered amphibian under environmental and demographic uncertainty. Population Ecology 66:184-195. link
Brooks, G. C., T. A. Gorman, K. C. Jones, H. C. Chandler, B. K. Rincon, M. A. Sission, J. Himes, and C. A. Haas. 2023. Removing duff layers in fire-suppressed wetlands can aid habitat restoration efforts. Wetlands 43:95. link
Chandler, H. C., N. M. Caruso, D. L. McLaughlin, Y. Jiao, G. C. Brooks, and C. A. Haas. 2023. Forecasting the flooding dynamics of flatwoods salamander breeding wetlands under future climate change scenarios. PeerJ 11:e16050. link
G. C. Brooks, A. Wendt, C. A. Haas, and J. H. Roberts. 2023. Comparing estimates of census and effective population size in an endangered amphibian. Animal Conservation 26:839-850. link
Brooks, G. C. and C. A. Haas. 2021. Using historical dip net data to infer absence of flatwoods salamanders in stochastic environments. PeerJ 9:e12388. link
Brooks, G. C., J. A. Smith, E. Frimpong, T. A. Gorman, H. Chandler, and C. A. Haas. 2019. Indirect connectivity estimates of amphibian breeding wetlands from spatially explicit occupancy models. Aquatic Conservation: Marine and Freshwater Ecosystems 29:1815-1825. link
diagnosing hellbender declines
Detecting declines and quantifying extinction risk of long-lived, highly fecund vertebrates can be challenging. In addition to the false notion that large clutches always buffer against population declines, the imperiled status of long-lived species can often be masked by extinction debt, wherein adults persist on the landscape for several years after populations cease to be viable. Here we develop a demographic model for the Eastern Hellbender (Cryptobranchus alleganiensis), an imperiled aquatic salamander with paternal care. We examined the individual and interactive effects of three of the leading threats hypothesized to contribute to the species’ demise: habitat loss due to siltation, high rates of nest failure, and excess adult mortality caused by fishing and harvest. Our model suggests that high rates of nest failure observed in the field are sufficient to drive hellbender populations towards a geriatric age distribution and eventually to localized extinction, but that this process takes decades. The combination of limited nest site availability due to siltation, nest failure, and stochastic adult mortality can interact to increase the likelihood and pace of extinction, and density-dependence in larval survival and recruitment can severely hamper a population’s ability to recover from declines. Our model helps to identify tipping points beyond which extinction becomes certain and management interventions become necessary. The most common intervention however - reintroduction of captive-bred animals - does not address the causes of declines. It is therefore unlikely to achieve recovery goals in isolation, and will require considerabel expense if reintroductions will have to be performed indefinitely. We used our modelling framework to evaluate various reintroduction strategies to see whether the expected benefit is worth the cost.
Publications
Brooks, G. C., H. K. Kindsvater, and W. A. Hopkins. A cost-benefit analysis of hellbender reintroduction strategies. in prep
Brooks, G. C., W. A. Hopkins, and H. K. Kindsvater. 2024. Concurrent threats and extinction risk in a long-lived, highly fecund vertebrate with parental care. Ecological Applications 34: e2946. link
Hopkins, W. A., B. F. Case, J. Groffen, G. C. Brooks, C. M. Bodinof Jachowski, S. T. Button, J. J. Halligan, R. S. M. O’Brien, and H. K. Kindsvater. 2023. Filial cannibalism leads to chronic nest failure of eastern hellbender salamanders. The American Naturalist 202: 92-106. link
bog turtle status assessment
Publications and Talks
Feaga, J. B., J. Barron, G. C. Brooks, E. A. Frimpong, C. A. Haas, M. Holden, and E. Hultin. 2024. A hydrologic and land cover-based habitat model for use in bog turtle (Glyptemys muhlenbergii) conservation. Aquatic Conservation: Marine and Freshwater Ecosystems 34:e4215. link
McDonnell, T. S., G. C. Brooks, M. T. Holden, J. D. Buckwalter, J. W. Snodgrass, and C. A. Haas. 2024. Investigating summertime vegetation density preference in bog turtles under grazing regime variation. Hudson Housatonic Recovery Unit Bog Turtle Meeting, Cold Spring, NY, USA.