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A. A. Karamanlidis et al. The Mediterranean monk seal

caves and fend off other approaching monk seals (Layna eastern Mediterranean is highest in autumn and winter,
et al. 1999). Aggressive interactions in the pupping caves during the peak pupping season of the species (Gücü et al.
between females and between females and pups are 2004, Dendrinos 2011). Cave use may also be influenced by
common (Dendrinos et al. 2007b, Karamanlidis et al. 2009, changes in the internal morphology of a cave (e.g. in Cabo
2013). Blanco; González et al. 1997), the state of the tide (e.g. in
Madeira; Pires et al. 2007) or the wave strength and direc-
tion (e.g. in the eastern Mediterranean Sea; Gücü et al.
GENETICS
2004, Dendrinos 2011). A major difference in the terrestrial
Genetic analyses of mitochondrial and nuclear DNA (Pastor habitat of Mediterranean monk seals occupying Cabo
et al. 2004, 2007, Karamanlidis et al. 2014b) have shown Blanco and those occupying the rest of the species’ range is
that, as a consequence of severe population bottlenecks and the number of marine caves. Whereas in Cabo Blanco, the
population fragmentation, all monk seal subpopulations entire monk seal subpopulation uses a small number (<5)
exhibit low levels of genetic diversity. In fact, the mitochon- of neighbouring marine caves for resting and pupping
drial DNA diversity of Mediterranean monk seals is among (Marchessaux & Muller 1987, Francour et al. 1990,
the lowest recorded in any pinniped species (Karamanlidis González et al. 1997, Martínez-Jauregui et al. 2012), in the
et al. 2014b). Low genetic diversity is an important factor in archipelago of Madeira and in the eastern Mediterranean,
the conservation of endangered species as it may, in combi- monk seals may occupy dozens or even hundreds of caves
nation with inbreeding depression, reduce fertility and (Gücü et al. 2004, Karamanlidis et al. 2004, Anonymous
increase infant mortality, thus resulting in an endangered 2007b, 2008b, 2009a).
species’ limited ability to cope with environmental change
(Frankham 1995).
PUPPING
Pupping in the monk seal colony at Cabo Blanco prior to
HABITAT
the mass die-off in 1997 was observed throughout the year,
Historical evidence suggests that Mediterranean monk seals with a small peak of births in September (Gazo et al. 1999,
once hauled out on open beaches (Johnson & Lavigne Pastor & Aguilar 2003). Following the mass die-off, a
1999a, Johnson 2004, González 2015). However, in more change in the reproductive parameters of the colony was
recent times throughout their range they frequent cliff- observed (González et al. 2002) and currently births are
bound coasts where they use marine caves for hauling out, recorded from April to November, with a clear peak in Sep-
resting and pupping. Pupping in caves is not ideal, as pups tember (Cedenilla et al. 2007). Also, since the mass die-off,
might become separated from their mothers during storms annual reproductive rates have increased from 0.25–0.43 to
and either drown or die from starvation. It is believed that 0.76 pups per female adult; the annual pupping rate has also
occupying such suboptimal habitat is partly a recent adapta- increased from 23 pups in 2000 to 69 pups in 2014 (Gazo
tion in response to human pressures (Johnson & Lavigne et al. 1999, Gazo et al. 2000b, unpublished data, CBD
1999a, Johnson 2004); similar behaviour has been observed Habitat). In all other parts of the species’ range, pupping
in other pinnipeds [e.g. Guadalupe fur seals Arctocephalus appears to be more synchronous. In the archipelago of
townsendi (Bernardi et al. 1998)]. In areas where conserva- Madeira, two to three pups are born annually, mostly
tion measures are in place and/or human activity is low (e.g. during the months October and November (Pires et al.
the protected areas at Cabo Blanco, the Desertas Islands 2008). The same pupping season has been recorded in Tur-
Nature Reserve and the island of Gyaros in Greece), monk key’s Cilician Basin (Gücü et al. 2004) and in Greece
seals may haul out on open beaches; on certain occasions (Dendrinos et al. 1994, 1999, Dendrinos 2011). In Greece,
even births on open beaches have been recorded (Pires & where only a small part of the entire coastline is systemati-
Neves 2000c, Fernandez de Larrinoa et al. 2007, Dendrinos cally monitored, 40 newborn pups are recorded on average
et al. 2008). annually (unpublished data, Hellenic Society for the Study
Most marine caves currently used by monk seals for and Protection of the Monk Seal; MOm).
resting and pupping possess a set of common geophysical During the lactation period, females leave their pups
characteristics, that include one or more entrances above or unattended for periods of on average nine hours in order to
below water level, an entrance corridor, an internal pool and forage, although absences up to 17 hours have been
a dry surface or area, where the seals haul out (Dendrinos reported (Gazo & Aguilar 2005). Fostering and milk stealing
et al. 2007c). Monk seals’ preferences regarding the use of a are common (Pires 2004, Aguilar et al. 2007, Karamanlidis
cave as a resting or pupping site are influenced by these et al. 2013). Some pups in the Cabo Blanco subpopulation
parameters (Karamanlidis et al. 2004, Dendrinos et al. have been fostered long-term by unrelated females (Aguilar
2007c). The frequency and intensity of cave use in the et al. 2007). Weaning of pups occurs at four to five months

Mammal Review (2015) © 2015 The Mammal Society and John Wiley & Sons Ltd 5