Low-level parasitic worm burdens may reduce body condition in free-ranging red deer (Cervus elaphus)

Abstract

Regulation of ungulate populations by parasites relies on establishing a density-dependent relationship between infection and vital demographic rates which may act through the effect of parasites on body condition. We examine evidence for parasite impacts in 285 red deer (Cervus elaphus) harvested during 1991 and 1992 on the Isle of Rum. In the abomasa, prevalence of nematodes was 100% and the most abundant genus observed were Ostertagia species, however, mean intensity of infection was low (less than 1000) relative to other studies. Additional species, also present in low numbers, included Nematodirus spp., Capillaria spp., Cooperia spp., Monieza expanza, Oesophagostomum venulosum and Trichuris ovis. Lungworm (Dictyocaulus spp.) and tissue worm (Elaphostronygylus cervi) larvae were also observed in faecal samples. There was no evidence for acquired immunity to abomasal nematodes. Despite low levels of infection, both adult male and female deer showed significant negative correlation between indices of condition (kidney fat index, dressed carcass weight and larder weight) and intensity of Ostertagia spp. infection. However, there was no evidence that pregnancy rate in females was related to intensity of infection. For calves, there was no relationship between body condition and intensity of infection. The apparent subclinical effects of low-level parasite infection on red deer performance could alternatively be due to animals in poorer nutritional state being more susceptible to infection. Either way the results suggest that further studies of wild populations are justified, in particular where high local host densities exist or alternative ungulate hosts are present, and, where experimental treatments are tractable.

Age Distribution and Seasonal Dynamics of Abomasal Helminths in Wild Red Deer from Central Spain

“…Grazing for fawns usually commences in the fall and would lead to acquisition of abomasal nematodes, representing those occurring in subadult hosts in the following year. Similar patterns have been documented for gastrointestinal nematodes in fallow deer (Kotrlá and Kotrlỳ, 1975) and reindeer (Halvorsen and Bye, 1999;Irvine et al, 2000).…”

“…Similar results were observed for abomasal infection in sheep (Díez-Baños et al, 1992) and some cervids (fallow deer, roe deer, and reindeer, Rangifer tarandus [Linnaeus]), where higher worm burdens were observed in adult hosts (Dunn, 1965;Dróżdż et al, 1987;Ambrosi et al, 1993;Rossi et al, 1997;Zaffaroni et al, 1997;Halvorsen and Bye, 1999;Irvine et al, 2000). On the contrary, O. drozdzi/O.…”

“…A high prevalence of abomasal infection, close to a 100%, and moderate intensity of infection appears to be typical among surveys for parasites in wild cervids (Ambrosi et al, 1993;Dróżdż et al, 1993Dróżdż et al, , 1994Zaffaroni et al, 1996;Dróżdż et al, 1997;Rossi et al, 1997;Suárez et al, 1997;García Romero et al, 2000;Irvine et al, 2006). Additionally, in these studies, as in red deer at Quintos de Mora, there were no significant differences in intensity of infection related to sex of host, although, in most cases, intensity of infection in males exceeds that observed in females.…”

Body condition is negatively associated with infection with Syngamus trachea in the ring-necked pheasant (Phasianus colchicus)

“…Previous studies failed to find any effect of gastrointestinal nematodes on host 39 condition in Reindeer populations in the High Arctic, however Irvine et al (2006), through the use of 40 delayed-release anthelmintic boluses, demonstrated reductions in host fitness in winter. Reindeer 41 populations were sampled previously when populations were more accessible, which highlights the 42 importance of timing research protocols to account for seasonal dynamics in the transmission of 43 parasites, and therefore any parasite-mediated effects.…”

Gastrointestinal Nematodes of Moose (Alces Alces) in Relation to Supplementary Feeding

“…Adult moose experiencing poor winter nutrition may invest fewer resources in immunity, prioritizing maintenance of body protein for survival in the shortterm and growth and reproduction in the longer-term (Coop and Kyriazakis, 2001). Such a lack of acquired immunity has been shown in Svalbard reindeer (Rangifer tarandus platyrhynchus; Irvine et al, 2000) and red deer (Cervus elaphus) in Scotland (Irvine et al, 2006). Our finding that juvenile females had a lower intensity of Trichostrongylidae infection than did juvenile males is typical for mammals with sex-specific differences in immunocompetence (Wilson et al, 2002).…”