Browsing by Author "Moore, Seth A."

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    R code and data for "Refining the moose serum progesterone threshold to diagnose pregnancy"
    (2022-04-06) Struck, Madeline; Severud, William J.; Chenaux-Ibrahim, Yvette M.; Isaac, Edmund J.; Brown, Janine L.; Moore, Seth A.; Wolf, Tiffany M.; seve0135@umn.edu; Severud, William J.
    Pregnancy determination is necessary for sound wildlife management and understanding population dynamics. Pregnancy rates are sensitive to environmental and physiological factors and may indicate the overall trajectory of a population. Pregnancy can be assessed through direct methods (rectal palpation, sonography) or indicated using hormonal assays (serum progesterone or pregnancy-specific protein B, fecal progestogen metabolites). A commonly used threshold of 2 ng/ml of progesterone in serum has been used by moose biologists to indicate pregnancy but has not been rigorously investigated. To refine this threshold, we examined the relationship between progesterone concentrations in serum samples and pregnancy in 87 moose (Alces alces; 64 female, 23 male) captured from 2010 to 2020 in the Grand Portage Indian Reservation in northeastern Minnesota, USA. Pregnancy was confirmed via rectal palpation (n = 25), necropsy (n = 2), calf observation (n = 25), or characteristic pre-calving behavior (n = 6), with a total of 58 females determined pregnant and 6 not pregnant; 23 males were included to increase the non-pregnant sample size. Using receiver operating characteristic analysis, we identified an optimal threshold of 1.115 ng/ml with a specificity of 0.97 (95% confidence interval [CI] = 0.90–1.00) and a sensitivity of 0.98 (95% CI = 0.95–1.00). Progesterone concentrations were significantly higher in cases of pregnant versus non-pregnant cows, but we did not detect a difference between single and twin births. We applied our newly refined threshold to calculate annual pregnancy rates for all female moose (n = 133) captured in Grand Portage from 2010 to 2021. Mean pregnancy rate during this period was 91% and ranged annually from 69.2 to 100%. Developing a reliable method for determining pregnancy status via serum progesterone analyses will allow wildlife managers to assess pregnancy rates of moose without devoting substantial time and resources to palpation and calf monitoring.
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    R code and data for "Spatial compartmentalization: a nonlethal predator mechanism to reduce parasite transmission between prey species"
    (2021-11-15) Oliveira-Santos, L. Gustavo R.; Moore, Seth A.; Severud, William J.; Forester, James D.; Isaac, Edmund J.; Chenaux-Ibrahim, Yvette M.; Garwood, Tyler; Escobar, Luis E.; Wolf, Tiffany M.; seve0135@umn.edu; Severud, William J.
    This collection of files provides data and R code supporting the publication "Spatial compartmentalization: a nonlethal predator mechanism to reduce parasite transmission between prey species" in review at Science Advances. We provide all necessary code to reproduce the analysis along with simulated movement data of white-tailed deer, moose, and wolves.
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    R code and data for "Terrestrial gastropod species-specific responses to forest management: implications for Parelaphostrongylus tenuis transmission to moose"
    (2022-12-14) Severud, William J; Petz Gigure, Matt; Walters, Tyler; Garwood, Tyler J.; Teager, Kim; Marchetto, Katherine M.; Oliveira-Santos, L. Gustavo R.; Moore, Seth A.; Wolf, Tiffany M.; seve0135@umn.edu; Severud, William
    Landscape management can influence the distribution, abundance, and diversity of the terrestrial gastropods that host known parasites of managed species of ungulates. Multiple taxa of terrestrial gastropods are important intermediate hosts in the lifecycle of the parasitic nematode Parelaphostrongylus tenuis, for which white-tailed deer (Odocoileus virginianus) are definitive hosts. Moose (Alces alces) become infected with P. tenuis when they incidentally ingest gastropod intermediate hosts, leading to morbidity and mortality. Populations of moose in Minnesota have declined and P. tenuis infection has been identified as a leading cause of mortality. We investigated the role of forest management disturbance on the terrestrial gastropod community, and specifically known intermediate host species of P. tenuis, on the Grand Portage Indian Reservation in northeastern Minnesota, USA, where moose are an important subsistence species to the Grand Portage Band of Lake Superior Chippewa. Field crews surveyed gastropods through timed searches of soil and litter, and opportunistic collections from browse and pellets of white-tailed deer and moose. We digested all identified gastropods to determine prevalence of P. tenuis infection. We examined gastropod community responses to management and forest cover type using multivariate regressions. We additionally used regressions to examine total gastropod richness and abundance, as well as P. tenuis intermediate host responses to cover type, soil moisture class, canopy cover, treatment, and years since treatment. Digestions detected no infected gastropods from the 621 identified specimens. Gastropod community assemblages differed with recent understory treatment, but no other predictors. Total gastropod abundance, richness, and host abundance (liberal definition, including Deroceras spp.) were lower in sites treated within the last five years. For known intermediate host taxa, we observed species-specific responses to forestry treatments through time. Specifically, Deroceras spp. recolonized sites post-treatment (0–30 years), Discus cronkhitei were higher in abundance immediately following treatment, and the Succinea ovalis group, along with pooled intermediate hosts, displayed no discernable patterns. Our results underscore the complexity of P. tenuis lifecycles and transmission dynamics to moose, the importance of management disturbance and disturbance frequency in regulating gastropod populations, and the potential of forest management treatments to reduce P. tenuis infection in moose.