Data di Pubblicazione:
2015
Citazione:
The use of uterine scars to explore fecundity levels in invasive alien tree squirrels / F. Santicchia, C. Romeo, G. Grilli, S. Vezzoso, L.A. Wauters, M.V. Mazzamuto, A. Martinoli, N. Ferrari. - In: HYSTRIX. - ISSN 0394-1914. - 26:2(2015), pp. 95-101. [10.4404/hystrix-26.2-11428]
Abstract:
In invasion ecology, reliable measures of female fecundity are necessary to infer population growth
rate and develop control programs to determine the proportion of animals that should be culled to
reduce population size. Here, we present a reliable staining technique of uterine scars to determine
individual fecundity in terms of both seasonal and total (annual) number of young born per
female. We applied this method to two alien squirrels species (grey squirrel, Sciurus carolinensis
and Pallas’s squirrel, Callosciurus erythraeus) introduced in Northern Italy, obtaining carcasses
from control campaigns from 2011 to 2013. We also investigated environmental and phenotypic
variables that might affect individual variation in fecundity and compared annual reproductive output
between the two species. For grey squirrels (n=44), 25% of examined females produced a single
litter and 61% two litters. Females which reproduced in both seasons tended to have larger summer
than spring litters (on average 2.61 and 1.94 offspring, respectively) and mean annual fecundity was
3.4 scars/female ranging from 1 to 8 births. There was no effect of year, eye lens weight, body size
or body mass on total fecundity. For Pallas’s squirrel (n=31), 58% of females had a spring litter,
some of these also produced a summer litter (35%) and a few even a third litter in autumn (10%).
Heavier and older females (higher eye lens weight) had more uterine scars than younger animals
with lower body mass. Finally, fecundity of the two IAS in Italy was similar or even higher than
in the native range and/or in other countries of introduction, suggesting they are well adapted to
their new environment and potentially have a high capacity to spread and recover after reduction of
population size.
Tipologia IRIS:
01 - Articolo su periodico
Keywords:
Callosciurus erythraeus; Sciurus carolinensis; litter size; staining technique; reproductive rate
Elenco autori:
F. Santicchia, C. Romeo, G. Grilli, S. Vezzoso, L.A. Wauters, M.V. Mazzamuto, A. Martinoli, N. Ferrari
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