Lactation and mother–pup behaviour in the Mediterranean monk seal Monachus monachus: an unusual pattern for a phocid

Abstract

This paper presents baseline information on maternal behaviour and lactation in the Mediterranean monk seal, with particular focus on the age at which pups are weaned. The study was conducted in the western Saharan population, the only surviving colony of the species. The first moult finished at a mean pup age of 72.3±17 d (N=17) and, in contrast to other taxonomically-related phocids, this process was not associated with weaning. Lactation lasted a mean of 119.4 d (N=9; range: 103–149 d) in the pups that could be monitored until full weaning had taken place. This period almost doubles the maximum lactation length reported in other phocid species. During the first week after birth the mother–pup bond was well developed and mothers always remained with their pups. The time invested in nursing (17%, SD: ±36) and in mother–pup interactions (14%, SD: ±32) was higher during this period than afterwards (8%, SD: ±23 and 4%, SD: ±19, respectively). After the first week, nursing continued but mothers started to leave their pups in order to feed at sea. Weaning occurred gradually. Already since birth, pups were active and mobile, and swam frequently before moulting or weaning occurred. Fostering and milk stealing were common patterns of behaviour for both lactating females and pups. In 26.6% of the suckling episodes observed in mother–pup pairs of known identity, pups suckled from females other than their mothers. Some females nursed more than one pup, at least occasionally, and in some cases a pup was fostered long-term by an alien female. The Mediterranean monk seal exhibits maternal-care characteristics that are more like otarids than phocids. This observation contradicts previous proposals that a short lactation period is a phylogenetic characteristic of phocids. Several of the unusual maternal traits observed may be favoured by year-round access to abundant food supply, availability of breeding sites, and mild climatic conditions. This information should be taken into account when designing conservation strategies for the species and, very particularly, in the implementation of pup rehabilitation programmes.

Twenty years of marine mammal research in Europe

“…Aguilar et al (2007) show that, in contrast to most phocids, the Mediterrean monk seal has an extended lactation period. In the only study from the present volume to focus on sirenians, Kiszka et al (2007) present evidence of associations between dugongs and dolphins in the Indian Ocean.…”

The mating system of the Mediterranean monk seal in the Western Sahara

“…These are severe handicaps for controlling females. Furthermore, 10 d after parturition, females start performing daily feeding trips offshore (Aguilar et al 2007) so they may disperse when coming into estrus (Pastor and Aguilar 2003). Hence, the low level of polygyny observed at Cap Blanc is not surprising and is comparable to that obtained for the other aquatically mating species studied: the two harbor seals subspecies (Coltman et al 1998, Hayes et al 2006) and the Weddell seal (Harcourt et al 2007 b ).…”

“…The reproductive system of the Mediterranean monk seal, Monachus monachus , is poorly characterized, although the information available suggests that at least some aspects of its reproduction may not fit the typical phocid pattern. This species has an unusually long lactation period (Aguilar et al 2007), and as a consequence females perform regular foraging dives (Gazo and Aguilar 2005), weaning occurs gradually (Aguilar et al 2007), and in the only extant colony surviving from the species and located at the Peninsula of Cap Blanc (Western Sahara), breeding females aggregate, forming large defensible groups (González et al 1997). However, other traits match the typical phocid pattern; for example, mating has occurred underwater on the few occasions in which it has been witnessed (Sergeant et al 1978, Marchessaux and Pergent‐Martini 1991, Pastor and Aguilar 2003).…”

The Mediterranean monk seal Monachus monachus: status, biology, threats, and conservation priorities

“…Some pups in the Cabo Blanco subpopulation have been fostered long‐term by unrelated females (Aguilar et al. ). Weaning of pups occurs at four to five months of age (Pastor & Aguilar , Aguilar et al.…”

“…Weaning of pups occurs at four to five months of age (Pastor & Aguilar , Aguilar et al. , Dendrinos ). At this time, pups begin to forage on their own (Pastor & Aguilar ).…”