Amy Haigh

Habitat selection, philopatry and spatial segregation in rural Irish hedgehogs ( Erinaceus europaeus )

Abstract As a non-territorial species with no known dispersal period, there are no obvious factors that regulate hedgehog numbers in an area. This study aimed to examine these factors and involved the radio-tracking of rural hedgehogs over a 3-year period. Males had a significantly larger mean annual home range (56 ha) than females (16.5 ha), which was at its maximum during the breeding season. Outside of the breeding season, the home range was relatively small (4–5 ha) in both sexes. The home ranges of males completely overlapped both each other and all of the females. In contrast, females occupied more exclusive areas with little overlap between one another. On a nightly basis, both sexes occupied spatially independent areas with little overlap. Compositional analysis of the data showed that habitats were not used in proportion to their availability but were selected, and this changed seasonally, with the highest preference being for garden and arable land. Hedgehogs tagged for consecutive years exhibited site philopatry and followed the same pattern of habitat selection annually. It is suggested that the spatial separation observed amongst individual hedgehogs could restrict numbers in an area and that female numbers reach a carrying capacity before that of males.

Intra- and interhabitat differences in hedgehog distribution and potential prey availability

Abstract With little previous research on the European hedgehog (Erinaceus europaeus Linnaeus) in Ireland, 22 hedgehogs (16 females and six males) were tagged at a rural Irish site between June 2008 and November 2009. Transect, surveying surface invertebrates were carried out in the centre and hedgerow in arable and pasture lands distributed throughout the site. In both years, hedgehogs selected arable land and this coincided with a rise in invertebrate density. This and the fact that within the arable field hedgehogs concentrated their activity where there was a greater density of potential prey suggest that hedgehogs learn the spatial location of prospective food. Contrary to other research, in most of the hedgehogs’ home range, individuals consistently foraged in the centre of both pasture and arable lands. Potential prey was lower in fields where the hedgerow had no bramble understory, and this suggests that hedgerow with good ground cover acts as an important reserve for invertebrates. Badgers (Meles meles Linnaeus) were seen on 12 occasions within the hedgehogs’ home range and they did not appear to have a negative effect on the hedgehogs’ use of the site. It was concluded that the main factor affecting the hedgehogs’ distribution within each habitat was the availability and accessibility of potential prey.

The preference for yew (Taxus baccata) by a red (Sciurus vulgaris) only squirrel population

Abstract Context. As invasive grey squirrels continue to spread, red only areas are becoming rarer. It has been reported that red squirrels can outcompete greys only in pure coniferous woodland. In areas of sympatry with grey squirrels, there are concerns about red squirrels’ dependence on certain coniferous tree species in light of recent tree diseases. Aims. This study aimed to investigate tree selection by red squirrels in an area vulnerable to the spread of the grey squirrel, but currently free of this species. Methods. During 2013–14, squirrels were trapped and monitored on a 315-ha managed island, with a woodland characterised by a mixture of deciduous and coniferous species. Radio-tracking revealed that squirrels clustered their activity along a network of yew trees, a preference they showed throughout the year. Trap success was also higher in traps placed on yew trees. Yew and beech were selected most commonly, but squirrels were also observed foraging on other items, such as sycamore flowers and lichen. Squirrels spent 35% of their time foraging, utilising the greatest number of tree species in June (n = 13). In spring, squirrels foraged to a greater extent on the ground than in the trees, and exploited a lower number of tree species. Conclusions. There has been little previous data on the use of yew trees by red squirrels, but they have previously been listed as a species that is preferred by red squirrels rather than greys. This study has further emphasised the importance of this tree species to red squirrels. Implications. The continued spread of the grey squirrel may lead to red squirrels becoming restricted to areas of intense management such as parks and, accordingly, optimum tree planting is required from the onset for the long-term maintenance of red squirrels. With recent concern about the disease vulnerability of other coniferous species, this study emphasises the relative importance of yew and other tree species in the distribution of red squirrels.

Hedgehog Erinaceus europaeus mortality on Irish roads

Hedgehogs are one of the most common mammalian road fatalities in Europe. Between April 2008 and November 2010, two stretches of road measuring 227 km (Cork City to Caherlistrane, Co. Galway) and 32.5 km (Cork City to Bandon, Co. Cork) respectively were surveyed for hedgehog road kill. In addition to the sightings of road kill on the two stretches of road, a further 135 carcasses were collected over the study period from throughout Ireland and the sex and age group were recorded. Over the three years, a total of 50 430 km were surveyed and 133 hedgehog fatalities were observed between the two surveyed roads. The number of hedgehog road kill per km in the current study was low when compared to countries such as Belgium, Poland and New Zealand. It is suggested that this may be a consequence of hedgehogs having a greater opportunity to encounter larger busier roads in other countries. Over the three years, the majority of the 133 carcasses sighted were located beside pasture, which was the most prominent habitat along both routes. Arable land was the only habitat used in a greater proportion than what was available. K-function analysis detected clustering along the surveyed roads, with fatalities clustering annually at several locations. This would suggest that hedgehogs may use specific crossing points which would be important for the implementation of management strategies and underpass construction. Of the 135 hedgehog carcasses collected from throughout Ireland there was significantly more males than females collected, with peaks in male deaths occurring in May and June. Female deaths only outnumbered males in August, with further peaks in female deaths observed in June and July. It is suggested that these peaks are related to the breeding season (adults) and dispersal/ exploration following independence (juveniles).

A preliminary investigation into the endoparasite load of the European hedgehog (Erinaceus europaeus) in Ireland

Abstract The European hedgehog is strictly protected in the Republic of Ireland but has been little studied. Carcasses, such as road kill casualties, can provide valuable information on population demographics, parasite load and general body condition. This study aimed to examine the species of endoparasites present in hedgehogs, their prevalence and intensities and whether differences occurred depending on the age and sex of the hedgehog. Carcasses were collected and examined from around Ireland, over a 3-year period. In 21 of the 23 hedgehogs examined, endoparasites were identified. The nematode species, Crenosoma triatum and Capillaria erinacei were both positively identified. C. striatium was confined to the lungs, whereas C. erinacei was the most prevalent (87%) endoparasite and occurred in the stomach and intestines. There was a significantly higher load of Crenosoma striatum observed in male hedgehogs compared to females, but no significant difference was observed in the intensity of C. erinacei between the sexes. In all tissues, a greater mean endoparasite load was observed in male hedgehogs. Sex differences in exposure or immunity to parasitism could be related to the males’ larger home range and the effects of oestrogen levels on immunity.