Ecology of Gastropod and Bighorn Sheep Hosts of Lungworm on Isolated, Semiarid Mountain Ranges in Utah, Usa

Abstract

ABSTRACT:Isolated, nonmigratory populations of bighorn sheep (Ovis canadensis) may experience high exposure to lungworms (Protostrongylus spp.) through a build-up of fecal material. However, semiarid climates may hinder lungworm transmission by limiting terrestrial gastropods, the intermediate hosts. We assessed potential for lungworm transmission, documented occurrence of transmission, and identified habitat types where transmission was likely to occur on ranges of two recently introduced populations of bighorn sheep in northern Utah. Gastropods were collected weekly on Antelope Island and the Newfoundland Mountains, May-August 2001-02, from each of the four major habitat types (riparian, rock, desert shrub, and grass). Distribution of 113 bighorn sheep groups was observed, and 421 fecal pellet groups were collected to estimate lungworm levels. A total of 1,595 gastropods representing five genera were collected from both ranges. Vallonia made up 85% of all gastropods collected. Of 980 gastropods collected on Antelope Island in 2002, only Vallonia were found infected with protostrongylid-type larvae (10 of 98051%). Lungworm prevalence in bighorn fecal samples was 97% on Antelope Island and 90% on the Newfoundland Mountains. Lungworm prevalence in lambs indicated lungworm transmission was occurring on Antelope Island. Lungworm transmission was likely occurring in riparian habitat due to abundant gastropods, presence of infected gastropods, and reliance by bighorn sheep on few water sources. Differences in spatial distribution between ram and nursery groups may partly explain higher fecal larvae counts in nursery than in ram groups. We suggest lungworm levels in bighorn sheep on semiarid ranges may increase in dry years as bighorn sheep concentrate use on fewer perennial water sources.

COMPARISON OF MODIFIED FLOTAC AND BAERMANN TECHNIQUES FOR QUANTIFYING LUNGWORM LARVAE IN FREE-RANGING BIGHORN SHEEP (OVIS CANADENSIS) FECES, MONTANA, USA

“…The bm-Baermann method improves the performance of the classic Baermann by exposing a greater surface area of feces and by preventing losses associated with larvae sticking to the walls of a Baermann funnel (Forrester and Lankester 1997a, b). Thus the bm-Baermann is widely used in bighorn sheep lungworm studies (Pelletier and Festa-Bianchet 2004;Goldstein et al 2005;Pelletier et al 2005;Rogerson et al 2008). Our results suggest that the bmBaermann performs as well as the FLO-TAC for estimating overall larval counts in bighorn sheep fecal samples.…”

Sexual segregation and use of water by bighorn sheep: implications for conservation

“…Human use of this area is restricted to hiking, biking and horseback riding on limited, designated trails (Fairbanks & Tullous, 2002). Greater detail regarding the flora and fauna of this area is available elsewhere (Fairbanks & Tullous, 2002;Rogerson, Fairbanks & Cornicelli, 2008;Whiting et al, 2009a).…”

“…We observed bighorn sheep an average of three times each month from April to November 2005 and 2006. We conducted ground observations during daylight in areas used by these animals (Rogerson et al, 2008;Whiting et al, 2009a;Olson et al, 2008). We observed bighorns from designated trails and from game trails leading to sources of water in bighorn habitat.…”

“…1). These springs were the only known perennial sources of water in proximity to habitat of bighorn sheep and ranged in elevation from 1290 to 1680 m (Rogerson et al, 2008;Whiting et al, 2009a;Whiting, Bowyer & Flinders, 2009b). Cameras were set at the same general location throughout the study, and within 15 m of the head waters of each spring (Whiting et al, 2009a,b).…”

Home Range and Parasite Diversity in Mammals

“…From this perspective, if larger home ranges are associated with less dense populations in mammals, animals with large home ranges should harbor fewer parasite species, at least for directly transmitted parasites. Moreover, various empirical studies have given support to the idea that indirectly transmitted parasites may depend on hosts aggregated around key (and often clumped) resources for short periods of time (for parasite transmissions around perennial water resources, see Vicente et al 2006;Rogerson et al 2008). Hosts with large home ranges may then miss these specific foci of transmissions, contrary to those with smaller home ranges.…”