Circuit theory is a tool to identify possible dispersal routes, assess functional landscape connectivity for small mammals

The majority of the world’s mammal fauna is small (67% of mammals are ≤ 240 g) and this presents major challenges for tracking since satellite tracking devices are still too large and/or costly to be feasibly implemented in long-term tracking and dispersal studies for small mammals.  Yet there is a pressing need to understand how small mammals respond to landscape features and make decisions about movement, as this information allows us to assess connectivity from the small mammal perspective. Natal dispersal presents an ideal opportunity to assess landscape connectivity for small mammals as this 1-way movement from a natal site to a new settlement location is often the longest movement an individual will make in its lifetime, and such movements are important to understand how far individuals of a species are capable of moving and for predicting whether metapopulation dynamics and gene flow can be maintained in the face of habitat loss, disturbance, and fragmentation.  However, for most small mammals, the high temporal resolution movement data necessary to fully understand how animals respond to and move through fragmented landscapes is difficult to obtain.  Fortunately, there are tools like circuit theory that can help us to fill in knowledge gaps about how small mammals may move within the landscape based upon movement and habitat use data that we do have.  In a new publication by KCRL’s Melissa Merrick and Dr. K, we generated three scenarios of possible landscape resistance from the perspective of dispersing Mt. Graham red squirrels (a small mammal) and used a program called Circuitscape to simulate squirrels as electrons moving within and responding to our resistance scenarios – moving from their place of birth to their settlement sites. Areas of high resistance are harder for electric current (and therefore simulated “squirrel electrons”) to move through and areas with the highest connectivity end up with the greatest number of simulated “squirrel electrons” moving through them, which is represented as electrical current.  We used circuit theory to identify areas that support long distance natal dispersal movements within a fragmented forest landscape as well as to assess which landscape resistance scenario best represents how dispersing red squirrels perceive barriers to movement.

Read more here:

Full citation: Merrick, M. J. and J. L. Koprowski 2017. Circuit theory to estimate natal dispersal routes and functional landscape connectivity for an endangered small mammal. Landscape Ecology DOI 10.1007/s10980-017-0521-z.


Areas of highest connectivity between natal sites (gray) and settlement sites (white) that may facilitate long distance natal dispersal movements in Mt. Graham red squirrels. This scenario is based upon the most permeable landscape resistance model. Brightest colors indicate highest current flow of simulated “squirrel electrons” moving within a specified model of landscape resistance. Green circles indicate exploratory dispersal movements.

Marina Morandini awarded University of Arizona GPSC research grant

KCRL PhD student Marina Morandini has been awarded the University of Arizona’s Graduate & Professional Student Council Research and Project Grant for her dissertation research.

The GPSC (Graduate & Professional Student Council) recognizes the important of academic research to advance professional level of students. Therefore, GPSC supports quality graduate and professional student research to continue the University of Arizona’s reputation as a leading research institution. Marina was awarded $1,000.00 for her project titled: “What makes a midden attractive? Impact of red squirrels on biodiversity.” Marina’s research focuses on ecosystem engineers,  mammals that exert strong physical changes to their environment, affecting resource availability and species distribution. Red squirrels can be considered an important type of ecosystem engineer since they contribute to the construction of shelter and nutritional resources in ecosystems by means of midden building (a form of food storage known as a larderhoard).  Middens are not only a fundamental attribute of red squirrel territory, but also a food resources for small mammals, which may in turn attract other predatory mammals and birds. Specifically, Marina’s research focuses on the Mt. Graham red squirrel (MGRS; Tamiasciurus fremonti grahamensis), found only on Mt. Graham (Arizona). Her project aims to understand which characteristics make a midden attractive to red squirrels and which impact they have to  presence/abundance of other species.

Congrats Marina!


Red squirrel midden used for storing cones


MGRS feeding on a Douglas-fir cone at its midden

Shambhu Paudel’s research on Ganges river dolphins featured in Onward Nepal

KCRL PhD student Shambhu Paudel‘s research on Ganges river dolphin (Platanista gangetica gangetic) ecology and conservation in Nepal is featured in a recent article in Onward Nepal news magazine.  Shambhu’s work to assess current population status and threats has been essential for the development of effective conservation and recovery plans for the species.

Shambhu, a World Wildlife Fund Russell E. Train Fellow and assistant professor at Tribhuwan University, is internationally recognized for his conservation work on this endangered species in Nepal. Shambhu is focused on understanding the causes of Ganges river dolphin population decline and developing strategies to mitigate risks and improve conservation efforts.

Read on:


Ganges river dolphins surfacing in the Karnali River, Nepal.  Photo by Shambhu Paudel

“The neighbor we know so little about” – Dr. K contributes to NPR piece on round-tailed ground squirrels

Visual story teller and wildlife artist, Beth Surdut, has an NPR essay series on watchable wildlife called “The art of paying attention”.  Her most recent installment focuses on round-tailed ground squirrels (Xerospermophilus tereticaudus) and she contacted Dr. K to discuss aspects of this species’ diet and behavior.  Dr. K describes round-tailed ground squirrels as “the neighbor we know so little about”.  So true!  The KCRL works to shed a bit more light on this and other unique and little-studied species we call neighbors.

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Where have all the squirrel emigrations gone? Dr. K weighs in

Imagine witnessing thousands of eastern gray squirrels (Sciurus carolinensis) moving across the landscape en masse, undeterred by barriers such as roads, waterways, or even people and horses!  An 1857 account reports “… thousands of squirrels crossed the road—some of them right over the horses and through the carriage— in a column that reportedly took a half hour to pass”.   Dr. K was consulted for a recent article on “squirrel migrations” by Mental Floss’s Colleen Kimmett.  Here Dr. K puts such movements in historical perspective and explains their ecological underpinnings as he discusses why these mass migrations (actually emigrations) occurred and why we are not likely to see them again any time soon.

Read on:


Eastern Gray Squirrel By ( [CC BY 3.0 (, via Wikimedia Commons




KCRL students help pull off successful earth week events, Marina Morandini among Earth Week poster competition winners

The University of Arizona’s School of Natural Resources and the Environment (SNRE) hosted a series of great Earth Week events this year, including a trivia night, a plenary with key note speakers, a poster competition, and an expo featuring different research groups and student organizations.  KCRL students did a fantastic job representing SNRE and helped to make Earth Week 2017 a success.  Special kudos to KCRL Sam Abercrombie, who worked with the SNRE graduate student organization to orchestrate all events and ensured a seamless execution.  Huge congratulations to KCRL PhD student Marina Morandini for receiving third place in the graduate student poster competition! So many great posters by graduate and undergraduate students this year made competition intense, and the top 3 winners in each category received cash prizes. Way to go!



KCRL’s Sam Abercrombie and Amanda Veals explain small mammal measurement techniques at the SNRE Expo


KCRL’s Colin Brocka (L) and Marina Morandini (R) discusses their research with judges and Department Chair, Dr. Marsh


Exciting events for Earth Week 2017

KCRL’s Mauricio Vela-Vargas featured in the news

KCRL PhD Student and Fulbright Scholar Mauricio Vela-Vargas is featured in the College of Agriculture and Life Sciences news!  Mauricio’s Fulbright funding will allow him to pursue a PhD studying Andean bears while continuing his conservation work with Proyecto de Conservación de Aguas y Tierras (ProCAT), a Colombian NGO which seeks to reduce human-wildlife conflicts while conserving habitat and protecting important connectivity areas necessary for the conservation of iconic and ecologically important species.

Read more here:

Nice work Mauricio!