Nesting behaviour and seasonal body mass changes in a rural Irish population of the Western hedgehog (<Emphasis Type="Italic">Erinaceus europaeus</Emphasis>)

There was previously no information on nesting, seasonal body mass or the hibernation behaviour of the hedgehog in Ireland. Between 2008 and 2009, hedgehogs were caught, weighed weekly and monitored by radio tracking at a rural Irish site. Day nests were recorded in the active period and hibernacula thereafter. Arable land has been reported to be poorly utilised by hedgehogs in the UK and Denmark. In Ireland, day nests and hibernacula were constructed in the hedgerows of arable land indicating that these areas will be exploited if hedgerow is maintained and highlights the importance of maintaining hedgerows in arable areas. Individual females returned to the same day nest significantly more than males. Over the 2 years, individuals were found to occupy a mean of 1.8 (±0.9; SD) hibernacula (maximum of 3) and they rotated between nests up to four times (mean of 2.5?±?1.6). When hedgehogs occupied multiple hibernacula, those occupied in mid winter (December and January) were occupied for significantly longer than those occupied at the start (October and November) and end (February and March) of hibernation. Studies in the UK and Denmark have reported on hedgehog hibernation. However, the winter climate in southern Ireland is milder than other areas of Europe and thus it was expected that hibernation characteristics would also differ, i.e. shorter hibernation periods, earlier emergence, lower body mass loss and the ability to survive hibernation at a lower body mass. This proved to be the case with a mean hibernation period (±SE) of 148.9 (±0.5) days, a mean body mass loss of 17.0 (±0.53) %, emergence in March and the ability of late juveniles to survive at a pre-hibernation body mass of 475 g.     

Non-invasive methods of separating hedgehog (Erinaceus europaeus) age classes and an investigation into the age structure of road kill

The separation of animals into age classes is often fraught with difficulties, but is essential for the interpretation of survival rates and population structure. This study investigated both live hedgehogs and road kill in order to develop techniques that could be utilised to separate age classes in the field. Body measurements were taken from 24 live hedgehogs caught at a site in County Cork, Ireland over a three year period. Additionally, carcasses from around Ireland were collected and measured. There was a significant correlation between the weight and hind foot length of both live and dead hedgehogs. The weight of individuals was also significantly correlated with the body length and jaw length of hedgehogs. In all of these correlations, the sample clustered clearly into two groups with ‘juveniles’ meeting all of the following criteria: a hind foot length of <3.6 cm, a body length of <?16 cm and a jaw length of below 4.5 cm. It is suggested that these parameters, combined with the presence of growing spines, could provide a way of separating age classes in the field. This would be of particular benefit to short term studies, allowing the population structure to be accurately assessed and the reproductive success and sustainability of a population to be investigated. Road kill were also aged using the dentary bone in order to investigate the age profiles of hedgehogs killed on the road. Amongst those killed, 54 % of hedgehogs were 1-year-old or less. The majority of hedgehogs (87 %) were between 0–3-years-old, the oldest females were nine (n?=?2), and the oldest males were eight years old (n?=?2), respectively. Road kill hedgehogs had an average longevity of 1.94 years, and the mean age of females was higher (2.10 years) than males (1.87 years).     

An in vitro transposon system for highly regulated gene expression: construction of Escherichia coli strains with arabinose-dependent growth at low temperatures.

Placing a gene of interest under the control of an inducible promoter greatly aids the purification, localization and functional analysis of proteins but usually requires the sub-cloning of the gene of interest into an appropriate expression vector. Here, we describe an alternative approach employing in vitro transposition of TnΩP_BAD to place the highly regulable, arabinose inducible P_BAD promoter upstream of the gene to be expressed. The method is rapid, simple and facilitates the optimization of expression by producing constructs with variable distances between the P_BAD promoter and the gene. To illustrate the use of this approach, we describe the construction of a strain of Escherichia coli in which growth at low temperatures on solid media is dependent on threshold levels of arabinose. Other uses of the transposable promoter are also discussed.