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Ecological lags in predator
and prey demography


Habitat loss and modification remain leading causes of species extinctions and population declines worldwide. These processes can result in delayed responses where generalist species may take years to decline, creating ‘extinction debts’. The benefits of habitat recovery and restoration on species recovery are often lagged as well, termed ‘colonization credits’.


We aim to (1) review current approaches to evaluating ecological lags in a world of multifaceted global change (2) propose a robust approach that can account for alternative stressors due of global change and correct for imperfect detection (3) implement this approach to evaluate ecological lags on prey demography (the Piute ground squirrel) resulting from three decades of habitat change in the Morley Nelson Snake River Birds of Prey National Conservation Area and (4) evaluate resulting ecological lags on the habitat use and nest productivity of their main predators (Prairie Falcons). 

Work is conducted in partnership with the Idaho National Guard, BLM, Boise State Raptor Research Center, and supported in part by GEM3 EPSCoR.

Credit to Trevor Jensen, Piute Ground Squirrel

Evaluating threats of habitat and
interspecies relationships


The Northern Aplomado Falcon is listed as an endangered species in the United States. Reintroductions of the species into a novel ecosystem are unlikely to succeed without an understanding of the effects of species interactions and habitat changes.


We aim to understand potential factors that may be hindering population recovery of Northern Aplomado Falcons at Laguna Atascosa National Wildlife Refuge and Aransas National Wildlife Refuge in Texas. The project goals are: (1) supplement the ongoing monitoring of nest occupancy and productivity of Northern Aplomado Falcons using cameras during breeding seasons, and (2) relate these demographic parameters to habitat and to the distribution of Barn Owls and Great Horn Owls at the refuge. This will allow us to (3) identify habitat requirements for breeding Northern Aplomado Falcons while considering increased risks from owls. Ultimate goals involve optimizing habitat management actions and determining the need for further priority actions to help enhance recovery of Northern Aplomado Falcons. This project is in partnership and support by the Peregrine Fund.

Credit to David Bontrager, Aplomado Falcon

Black-tailed jackrabbit.jpg

Evaluating ecological trade-offs of small mammals in semi-arid ecosystems under climate change

Leporidae species, including black-tailed jackrabbits, are key prey to several medium- and large-sized predators including endangered species such as Golden Eagles (Aquila chrysaetos) and bobcats (Lynx rufus) (Simes et al. 2015). However, little is known about Leporids current distribution, or demographic responses to the rapid and ongoing landscape changes. We therefore aim to develop a solid baseline of their spatial distribution and abundance for different habitats within the sagebrush steppe.

Our goals are (1) develop an improved, rigorous approach for sampling Leporid abundance at landscape levels. (2) Apply our learning of rigorous sampling design to sample the distribution and abundance of black-tailed jackrabbits at the Morley Nelson Birds of Prey National Conservation Area within 5 key habitat types. This project is supported by Epscor GEM3, in collaboration with USGS, FWS, and the Idaho National Guard.  

Black-tailed jackrabbit

Improving species recovery and reintroductions

The rate of species extinctions and declines continues to rise at an alarming rate. Reversing these dire trends with limited conservation funds requires management efforts that lead to effective and long-lasting population recoveries.

In collaboration with U.S. Geographical Survey and the National Park Service, we used an Integrated Population Model to demonstrate that managing individual nests, scales-up to faster population recovery of bald eagles (Cruz et al. 2018, J. Applied Ecol.). We also evaluated top-down (i.e., recovering bald eagles) and bottom-up factors (i.e., food, weather and nesting habitat) influencing the joint recovery of osprey and great blue herons over 26 years in Minnesota (Cruz et al. 2019, J. Animal Ecol.). The recovery of bald eagles hindered the recovery of ospreys and herons. Achieving ecosystem benefits of returning top predators thus requires multi-species management. 

Credit to Jeremy Cohen, Osprey

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