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1. Modeling the Effects of Ehrlichia chaffeensis and Movement on Dogs

   https://doi.org/10.1155/2024/6878662  

   Agusto, Folashade B; Drum, Jaimie (January 2024, Complexity)

   Cai, Ning (Ed.)

   Ehrlichia chaffeensisis a tick‐borne infectious disease transmitted byAmblyomma americanumtick. This infectious disease was discovered in the 1970s when military dogs were returning from the Vietnam War. The disease was found to be extremely severe in German Shepherds, Doberman Pinschers, Belgium Malinois, and Siberian Huskies. In this study, we developed a mathematical model for dogs and ticks infected withEhrlichia chaffeensiswith the aim of understanding the impact of movement on dogs as they move from one location to another. This could be a dog taken on a walk in an urban area or on a hike in the mountains. We carried out a global sensitivity analysis with and without movement between three locations using as response functions the sum of acutely and chronically infected ticks and the sum of infected ticks in all life stages. The parameters with the most significant impact on the response functions are dogs disease progression rate, dogs chronic infection progression rate, dogs recovery rate, dogs natural death rate, acutely and chronically infected dogs disease‐induced death rate, dogs birth rate, eggs maturation rates, tick biting rate, dogs and ticks transmission probabilities, ticks death rate, and the location carrying capacity. Our simulation results show that infection in dogs and ticks are localized in the absence of movement and spreads between locations with highest infection in locations with the highest rate movement. Also, the effect of the control measures which reduces infection trickles to other locations (trickling effect) when controls are implemented in a single location. The trickling effect is strongest when control is implemented in a location with the highest movement rate into it. 

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2. Geographic Distribution and Seasonality of Brown Dog Tick Lineages in the United States

   https://doi.org/10.1093/jme/tjac172  

   Grant, Amber N.; Lineberry, Megan W.; Sundstrom, Kellee D.; Allen, Kelly E.; Little, Susan E.; Hamer, ed., Sarah (November 2022, Journal of Medical Entomology)

   Abstract Two lineages of brown dog ticks (Rhipicephalus sanguineus sensu lato (s.l.), Latreille [Acari: Ixodidae]) have been described in North America: temperate and tropical. To characterize the distribution of these lineages across this region and evaluate seasonal activity, a 12S rRNA mitochondrial gene fragment was sequenced from R. sanguineus s.l. collected from hundreds of dogs and cats from different locations across 25 of the 50 states from 2018 to 2021. Infestations with temperate lineage predominated (78.5%) and were identified on pets from 20 states, with most (83.5%) from areas with annual mean daily average temperature <20°C. Tropical lineage submissions were less common (19.3%), submitted from 15 states, and most (80.0%) tropical lineage ticks were from areas with an annual mean daily average temperature >20°C. Although travel history was not obtained for all dogs, when tropical lineage infestations were found in colder regions, follow up conversations with veterinarians suggested some of these infestations may have resulted from recent travel of dogs. A limited number (2.2%) of dogs from Arizona and Texas were co-infested with both lineages. Both temperate and tropical lineage ticks were collected from pets in every month of the year. Temperate lineage infestations were primarily collected March through August while tropical lineage infestations were more often collected June through November. These data confirm at least two lineages of R. sanguineus s.l. are present in the United States, each predominating in distinct, overlapping geographies, and suggest that peak activity of each lineage occurs at different times of the year. 

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3. African wild dog movements show contrasting responses to long and short term risk of encountering lions: analysis using dynamic Brownian bridge movement models

   https://doi.org/10.1186/s40462-022-00316-7  

   Goodheart, Ben; Creel, Scott; Vinks, Milan A.; Banda, Kambwiri; Reyes de Merkle, Johnathan; Kusler, Anna; Dart, Chase; Banda, Kachama; Becker, Matthew S.; Indala, Peter; et al (December 2022, Movement Ecology)

   Abstract Background Prey depletion is a threat to the world’s large carnivores, and is likely to affect subordinate competitors within the large carnivore guild disproportionately. African lions limit African wild dog populations through interference competition and intraguild predation. When lion density is reduced as a result of prey depletion, wild dogs are not competitively released, and their population density remains low. Research examining distributions has demonstrated spatial avoidance of lions by wild dogs, but the effects of lions on patterns of movement have not been tested. Movement is one of the most energetically costly activities for many species and is particularly costly for cursorial hunters like wild dogs. Therefore, testing how top-down, bottom-up, and anthropogenic variables affect movement patterns can provide insight into mechanisms that limit wild dogs (and other subordinate competitors) in resource-depleted ecosystems. Methods We measured movement rates using the motion variance from dynamic Brownian Bridge Movement Models (dBBMMs) fit to data from GPS-collared wild dogs, then used a generalized linear model to test for effects on movement of predation risk from lions, predictors of prey density, and anthropogenic and seasonal variables. Results Wild dogs proactively reduced movement in areas with high lion density, but reactively increased movement when lions were immediately nearby. Predictors of prey density had consistently weaker effects on movement than lions did, but movements were reduced in the wet season and when dependent offspring were present. Conclusion Wild dogs alter their patterns of movement in response to lions in ways that are likely to have important energetic consequences. Our results support the recent suggestion that competitive limitation of wild dogs by lions remains strong in ecosystems where lion and wild dog densities are both low as a result of anthropogenic prey depletion. Our results reinforce an emerging pattern that movements often show contrasting responses to long-term and short-term variation in predation risk. 

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4. Gunnison's Prairie Dog Restoration Experiment (GPDREx): Vegetation Cover Data from the Sevilleta National Wildlife Refuge, New Mexico (2011-2016)

   https://doi.org/10.6073/pasta/696c2d207b59556dd39d44eb656dda23  

   Baker, Stephanie; Davidson, Ana (January 2021, Environmental Data Initiative)

   Prairie dogs (Cynomys spp.) are burrowing rodents considered to be ecosystem engineers and keystone species of the central grasslands of North America. Yet, prairie dog populations have declined by an estimated 98% throughout their historic range. This dramatic decline has resulted in the widespread loss of their important ecological role throughout this grassland system. The 92,060 ha Sevilleta NWR in central New Mexico includes more than 54,000 ha of native grassland. Gunnison's prairie dogs (C. gunnisoni) were reported to occupy ~15,000 ha of what is now the SNWR during the 1960's, prior to their systematic eradication. In 2010, we collaborated with local agencies and conservation organizations to restore the functional role of prairie dogs to the grassland system. Gunnison's prairie dogs were reintroduced to a site that was occupied by prairie dogs 40 years ago. This work is part of a larger, long-term study where we are studying the ecological effects of prairie dogs as they re-colonize the grassland ecosystem. 

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5. An integrated population model reveals source‐sink dynamics for competitively subordinate African wild dogs linked to anthropogenic prey depletion

   https://doi.org/10.1111/1365-2656.14052  

   Creel, Scott; Reyes de Merkle, Johnathan; Goodheart, Ben; Mweetwa, Thandiwe; Mwape, Henry; Simpamba, Twakundine; Becker, Matthew S (April 2024, Journal of Animal Ecology)

   Abstract Many African large carnivore populations are declining due to decline of the herbivore populations on which they depend. The densities of apex carnivores like the lion and spotted hyena correlate strongly with prey density, but competitively subordinate carnivores like the African wild dog benefit from competitive release when the density of apex carnivores is low, so the expected effect of a simultaneous decrease in resources and dominant competitors is not obvious.Wild dogs in Zambia's South Luangwa Valley Ecosystem occupy four ecologically similar areas with well‐described differences in the densities of prey and dominant competitors due to spatial variation in illegal offtake.We used long‐term monitoring data to fit a Bayesian integrated population model (IPM) of the demography and dynamics of wild dogs in these four regions. The IPM used Leslie projection to link a Cormack–Jolly–Seber model of area‐specific survival (allowing for individual heterogeneity in detection), a zero‐inflated Poisson model of area‐specific fecundity and a state‐space model of population size that used estimates from a closed mark–capture model as the counts from which (latent) population size was estimated.The IPM showed that both survival and reproduction were lowest in the region with the lowest density of preferred prey (puku,Kobus vardoniiand impala,Aepyceros melampus), despite little use of this area by lions. Survival and reproduction were highest in the region with the highest prey density and intermediate in the two regions with intermediate prey density. The population growth rate () was positive for the population as a whole, strongly positive in the region with the highest prey density and strongly negative in the region with the lowest prey density.It has long been thought that the benefits of competitive release protect African wild dogs from the costs of low prey density. Our results show that the costs of prey depletion overwhelm the benefits of competitive release and cause local population decline where anthropogenic prey depletion is strong. Because competition is important in many guilds and humans are affecting resources of many types, it is likely that similarly fundamental shifts in population limitation are arising in many systems. 

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