Social Behaviour of the Spotted-Necked Otter

Territory

In ideal habitat, one adult occupies about a kilometre of lake shore, or about 2 miles of river, bank and undergrowth. Each male has a big home range, with one or more female territory in it. Lejeune (1989 and 1990) found that territorial meetings could be friendly or aggressive depending on whether the otters were related, and also the individual animals' temperaments.

Holt

According to Davies in Otters: Proceedings of the First Working Meeting of the Otter Specialist Group (1977), these animals will have one or more holts in their territory, with one or more entrances, one of which is usually under water.

Daily Activity

On the great lakes of Africa. Such as Lake Victoria, these otters are diurnal, with activity peaks on the early morning and later afternoon, and in between, resting up in dense vegetation, especially on islands. In other habitats they are nocturnal. However, they are quick to adapt - on the lakes they do come out at night to raid nets, and in some places have learnt to wait for discarded fish from returning fishermen. (Kruuk (1995), Davies (IUCN, 1977) and Lejeune (1989)).

Sociability

There are many conflicting accounts of the social behaviour of this species.

On the whole, people have found these otters tolerant of one another rather than truly social. Despite this, there are several accounts of groups of 20 or more (e.g. Proctor (1963)) in the great lakes of Africa, foraging singly, but swimming in tight packs to cover distance. The normal group size seen was around five otters. Other observers ( Lejeune (1989), Kwa-Zulu Natal Wildlife Management Services) found the animals to be far more solitary, with males having a large territory covering several smaller territories belonging to females.

There seem to be three main views as to why these otters aggregate into large groups.

  1. Food Supplies: if food tends to occur in concentrations with little between the clusters, e.g. fish in shoals, it makes sense for many otters to exploit the shoal, following it closely ( Kruuk (1995)).
  2. Protection from Predators: since spotted-necked otters are preyed on by eagles and crocodiles, perhaps a pack offers protection ( Kruuk (1995)).
  3. ( Kingdon (1977)) believed that the big groups follow a seasonal cycle, with males and females forming separate groups. The males leave their groups in June to August to mate, but since they are not subsequently tolerated by the females, return to their groups again.
The smaller groups seen, of five or six otters, are probably families as cubs stay with their mother until well after the next cubs are born (Davies in Otters: Proceedings of the First Working Meeting of the Otter Specialist Group (1977)).

Spotted-Necked Otter