Decline in body condition and high drought mortality limit the spread of wild chital deer in north-east Queensland, Australia

Chital deer (Axis axis) were introduced to the Burdekin district of northern Queensland, Australia in 1886. Compared with most successful ungulate introductions they have been slow to expand their distribution and increase in abundance (Moriarty 2004). In this study we consider the possibility that forage shortages caused by periodic droughts have caused sufficient mortalities to limit the increase and spread of chital in the region. The Burdekin district experiences fluctuations in forage according to seasonal rainfall as well as multi-year droughts. This study recorded the decline in body condition, measured as kidney fat index (KFI) and bone marrow fat (BMF), over the wet and dry seasons of two successive years in two chital deer populations during a period when annual rainfall was ~40% below average. We relate the falls in mean KFI from ~45–15%, and mean BMF from ~80–50% to the surveyed decline in chital populations of ~80%. The extent of the decline implies increased mortalities in all age classes as well as reduced reproductive output. We propose that it is likely that chital populations have experienced several such drought mortality events since the 1890s which have contributed to their limited spread.

Comparative analysis of body weight and condition in two brown hare populations

The condition of the populations are useful parameters for the reasonable game management. In this study the physical condition of Brown hare stocks (Lepus europaeus, Pallas 1785) was analyzed, measured body weight (BW) and determined kidney fat index (KFI). These methods were applied during our survey in the hunting period of 2014/15 and 2015/16. In total 272 (123 male and 149 female) samples were collected from two hunting areas in Great Plain (from County Békés and Jász-Nagykun Szolnok). The aim of our work was to collect data concerning the conditions of the populations. All hares was sexed and classified in 2 age groups (young <1years), and (old> 1years). The age was established by Stroh-mark in the hunting field and by dried eye lenses in the laboratory. BW and the weight of the kidney and perirenal fat was measured and the data were statistically analysed (group statistics, Levene’s test for Equality of Variances and, t-tests for Equality of Means). As a result of our examination the range of KFI was 1.25-5.14. The weight of perirenal fat was between 2-34gramm.KFI was greater in females than males. The average BW of the hares in every age groups were less than it is according to literature dates, however the conditions of the hares were good and in very good in both hunting areas. The BW and the amount of the perirenal fat in adult female hares were the greatest.

The helminth parasites of the wild rabbitOryctolagus cuniculusand their effect on host condition in Dunas de Mira, Portugal

The present study focuses on the helminth parasite community of the wild rabbit in a sand dune area in Portugal over a 5-year period. The influence of host sex and year on the composition of the helminth community is assessed, along with the potential effect of the detected helminths on host body condition. The basic structure of the helminth community comprisesMosgovoyia ctenoides,Graphidium strigosum,Trichostrongylus retortaeformis,Nematodiroides zembraeandPassalurus ambiguus. Mean intensities ofG. strigosumvaried between years. GeneralG. strigosumintensities were also found to vary according to both year and host sex, but not according to the interaction of both factors. When assessing the effect of helminths on rabbit body condition (expressed by the kidney fat index), higher burdens ofM. ctenoides, a cestode that presents a relatively large body mass, were found to induce a reduction in rabbit condition.

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

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.

Body condition assessment and prediction of fasting endurance in wild rabbits (Oryctolagus cuniculus)

In many species, reproductive success, resistance to food shortage and immune response to parasitism depend on body nutrient reserves. Thus, determining body fuels is important for studying the impact of the environment on animal fitness. As an alternative to the usual biochemical methods, we have defined models for estimating body composition in rabbits (Oryctolagus cuniculus). The accuracy of the indices obtained on a source group was tested on an independent group. The models were applicable regardless of age, sex or season. The intact body mass already accounted for 90% of the protein variability. The most accurate equation combining dry body mass and interscapular fat mass explained 99% of the protein variations. Intact body mass and the kidney fat index were poor estimators of lipid stores (r2 = 0.45) but 90% of the variation was explained by an equation combining the interscapular fat mass and the hind leg length. None of the predictive equations significantly over- or underestimated body reserves. The usefulness of the models was assessed by estimating fasting endurance during winter. Individual estimates, ranging from two to eight days, did not differ by more than 0.5 day from the fasting endurance obtained from actual mobilisable body nutrients. In such lean species (adiposity 2–4%), proteins may account for up to 40% of the available energy reserves and survival is likely to be linked to the continuous availability of food resources. These results stress the need to determine proteins and not only lipids to have a pertinent tool for the management of wild animal populations, particularly in lean species.

Significant relationships between the serum leptin concentration and the conventional fat reserve indices in a wildlife species, Hokkaido sika deer (Cervus nippon yesoensis)

We assayed the serum leptin concentration and determined its correlation with the kidney fat mass (KFM), kidney fat index (KFI), and femur marrow fat (FMF) indices in 12 Hokkaido sika deer (Cervus nippon yesoensis Heude, 1884) collected in April, June, and October 2000. The KFM and KFI in April and June were both significantly lower than those in October. The leptin concentrations in April and June and in October were 1.222–1.521 ng mL–1 HE (Human Equivalent) units and 1.676–2.63 ng mL–1 HE, respectively, without overlapping. The relationships between the leptin concentration and the KFM, KFI, and FMF were all significant. Therefore, we conclude that the serum leptin concentration can be used as a new index for fat reserves in Hokkaido sika deer. However, reliable results could not be obtained from four samples collected in April and June when the deer were in a lower nutritional status. This may be due to the limited sensitivity of the antisera in the commercial multi-species leptin RIA kit used. For practical use in wildlife biology, species-specific leptin assays should be developed to eliminate this problem.

The potential role of habitat on intestinal helminths of mountain hares, Lepus timidus

Over the last century in the uplands of Scotland, the extent of heather moorland which supports high densities of mountain hares Lepus timidus has diminished and has gradually been replaced by large-scale commercial forestry plantations or expanding natural woodlands. The potential impact of such a change in land use on host–parasite interactions was investigated by comparing the intensity and prevalence of infection of hares by parasites in two separate habitats: a large hare-fenced young forestry plantation and the adjacent open moorland. Carcasses were collected in November 1990 from within both habitats and after the woodland had been enclosed for nine months. Age, sex, fatness (kidney fat index) and degree of infection of hares were noted. Two parasites were recorded: the nematode Trichostrongylus retortaeformis and the cestode Mosgovoyia pectinata. Clear differences in the intensity of infection of adults occupying the different habitats had occurred in the nine months since woodland enclosure. Adult mountain hares in the woodland had levels of infections approaching four times that observed in hares occupying the open moorland and although not significant, the prevalence of infection was greater in hosts inhabiting the woodland than the open moorland. It is suggested that the parasite–host relationship differs between the two habitats and as heather-dominated moorland landscapes become more fragmented with the increasing establishment of woodlands, the impact of parasites on the life history strategies of mountain hares needs to be reconsidered.