Bunnell (2009) hedgehog growth rate early Vs late litters
Title: Growth rate in early and late litters of the European hedgehog (Erinaceus europaeus), Lutra 52(1); 15-22, 2009.
Authors: T. Bunnell
Background to study
Successful hibernation has been found to be dependent on the amount of fat accumulated prior to hibernation and thus the size and weight gain of juveniles is particularly important component to their survival. This study uses data collected over a nine-year period from juvenile hedgehogs admitted into a sanctuary to investigate the growth rates of early and late born litters to determine whether late born young are more at risk to overwinter mortality.
- Juvenile hedgehogs were admitted to an RSPCA hedgehog sanctuary after being identified by members of the public as being in need of care.
- Early litters were defined as all young hedgehogs, weighing no more than 255g, that arrived at the sanctuary between June and the end of August in the same year.
- Late litters were defined as all young hedghogs that arrived at the sanctuary between September and the end of January the following year.
- Daily weight recordings from 119 hedgehogs admitted for treatment were used to investigate the growth rates and differences between early and late born individuals.
- Sick animals, which accounted for 26% of admissions ,were not included in the analyses of growth rates.
- All young individuals were fed Esbilac milk substitute for puppies and were gradually introduced to Pedigree Chum Complete Puppy dog food and dried biscuits specifically manufacturered for hedgehogs or kittens.
- Animals from early litters (n = 81) accounted for 61.3% of sick animals whilst those from late litters (n=38) accounted for 32.3%. Of the early litters, 23.5% were sick compared with 31.6% of late litters.
- The number of hedgehogs admitted was highest in June and were dominated by individuals weighing 40-120 g. The lowest number of admissions was in December and January when only individuals weighing over 201 g were admitted.
- Very young animals weighing 40-120 g were admitted every month between June and October.
- The overall growth rates of young born to late litters were significantly higher than young born to early litters with the mean grams per day gained in weight being 10.87 and 12.55 for early and late litter juveniles respectively.
- No significant difference in growth rate was found between males (mean = 11.57g/day) and females (10.87g/day) for either early or late litters.
- The mean growth rate for each month that young hedgehogs arrived was lowest in July and highest in September.
Key messages to landowners and managers derived from these results
- Late born litters may have increased chances of survival over hibernation due to increased growth rates and thus public intervention if the mother is present with young may not be necessary in all instances.
- Breeding occurs between June and October and must be accounted for when disturbance to key hedgehog habitat is proposed.
- Data on weight and survival from hedgehogs in captive environments should be obtained to provide information on key demographic parameters that are useful for both in-situ and ex-situ management for hedgehog conservation.