Resource availability influences global social network properties in Gunnison’s prairie dogs (Cynomys gunnisoni)

Increasingly we are discovering that the interactions between individuals within social groups can be quite complex and flexible. Social network analysis offers a toolkit to describe and quantify social structure, the patterns we observe, and evaluate the social and environmental factors that shape group dynamics. Here, we used 14 Gunnison’s prairie dogs networks to evaluate how resource availability and network size influenced four global properties of the networks (centralization, clustering, average path length, small word index). Our results suggest a positive correlation between overall network cohesion and resource availability, such that networks became less centralized and cliquish as biomass/m2 availability decreased. We also discovered that network size modulates the link between social interactions and resource availability and is consistent with a more ‘decentralized’ group. This study highlights the importance of how individuals modify social cohesions and network connectedness as a way to reduce intragroup competition under different ecological conditions.

A Novel Retrovirus (Gunnison’s Prairie Dog Retrovirus) Associated With Thymic Lymphoma in Gunnison’s Prairie Dogs in Colorado, USA

As part of research and wildlife disease surveillance efforts, we performed necropsy examinations of 125 free-ranging (n = 114) and captive (n = 11) prairie dogs in Colorado from 2009 to 2017. From these cases, we identified three cases of thymic lymphoma in free-ranging Gunnison’s prairie dogs (Cynomys gunnisoni), and we identified a novel retroviral sequence associated with these tumors. The viral sequence is 7700 nucleotides in length and exhibits a genetic organization that is consistent with the characteristics of a type D betaretrovirus. The proposed name of this virus is Gunnison’s prairie dog retrovirus (GPDRV). We screened all 125 prairie dogs for the presence of GPDRV using PCR with envelope-specific primers and DNA extracted from spleen samples. Samples were from Gunnison’s prairie dogs (n = 59), black-tailed prairie dogs (Cynomys ludovicianus) (n = 40), and white-tailed prairie dogs (Cynomys leucurus) (n = 26). We identified GPDRV in a total of 7/125 (5.6%) samples including all three of the prairie dogs with thymic lymphoma, as well as spleen from an additional four Gunnison’s prairie dogs with no tumors recognized at necropsy. None of the GPDRV-negative Gunnison’s prairie dogs had thymic lymphomas. We also identified a related, apparently endogenous retroviral sequence in all prairie dog samples. These results suggest that GPDRV infection may lead to development of thymic lymphoma in Gunnison’s prairie dogs.

Alarm calls of the same individual vary during a response to the same predator in Gunnison’s prairie dogs (Cynomys gunnisoni)

Many animals emit vocalizations in a repetitive series, but are all the calls within a series structurally the same? To answer this question, we recorded the barks of adult female Gunnison’s prairie dogs (Cynomys gunnisoni (Baird, 1855)) during 5 min experimental presentations of several terrestrial stimuli. We measured eight variables (primarily pitch and duration measures) of the first, middle, and last barks in each bout of barking produced by each of 24 females, as well as the duration of inter-bout intervals, the number of barks per bout, and the rate of barking per bout. We found that first barks were significantly longer and higher pitched than middle or last barks. Some of these differences were affected by the number of barks in a bout. Regardless of bark position, barks became longer and lower pitched in later bouts, and inter-bout intervals, number of barks per bout, and the rate of barking per bout all declined in later bouts. Our results show that bark structure can vary even within a single context and within a short period of time. Thus, variation due to call position within and across bouts of calling is a potentially important confound for studies examining other sources of acoustic variation.