Research

Vocal mother-offspring communication in guinea pigs: females adjust maternal responsiveness to litter size

Melanie Kober¹ , Fritz Trillmich¹ and Marc Naguib^1,2

¹  Department of Animal Behaviour, University Bielefeld, P.O. Box 100 131, 33501 Bielefeld, Germany

²  Netherlands Institute of Ecology (NIOO-KNAW), Department of Population Biology, P.O. Box 40, 6666 ZG Heteren, The Netherlands

author email corresponding author email

Frontiers in Zoology 2008, 5:13doi:10.1186/1742-9994-5-13

Published:	10 September 2008

Abstract

Background

In parent-offspring communication, vocal signals are often used to attract attention and offspring might call to induce parental behaviour. In guinea pigs (Cavia aperea f. porcellus) mothers wean larger litters later than small ones, but it is unknown whether this difference depends on processes induced during pregnancy or is influenced post-natally by the number of pups present. We here tested with playback-experiments using pup separation calls whether mothers with cross-fostered large experimental litters (four-pup-litters) were more responsive to offspring calls and maintained responsiveness for longer than mothers with small experimental litters (two-pup-litters). Mothers were tested when two pups were suckling i.e. when both teats were occupied.

Results

Mothers of four-pup litters responded stronger to broadcast pup separation calls than those with two-pup litters. Additionally, we tested the mothers' responsiveness to pup separation calls in the absence of their pups on day 8 and 20 of lactation. Mothers of four-pup litters responded stronger and showed no decrease in responsiveness from day 8 to 20, whereas mothers of two-pup litters responded less and decreased responsiveness from day 8 to 20. Mothers of four-pup litters also weaned their pups 5 days later than those of two-pup litters.

Conclusion

Measured by their response to pup calls and by time to weaning, guinea pig mothers adjust maternal responsiveness to litter size. This behaviour is likely to be an adaptive strategy in resource allocation during reproduction.