Spot-necked Otter (Hydrictis maculicollis) Fact Sheet: Behavior & Ecology

• Primarily diurnal; most active in morning and late afternoon (Rowe-Rowe 1978).
  • Emerge from dens (holts) before dawn and fish for about 2.5 hours at Lake Victoria in Tanzania. (Procter 1963)
• Spend considerable time grooming fur by biting and scratching it, not licking. (Procter 1963)
• Nocturnal in South Africa's Kamberg Nature Reserve, KwaZulu-Natal Province (Rowe-Rowe 1992); nocturnal activity increases during full moons. (Perrin & D'Inzillo Carranza 2000).
  • Prey detection, usually by sight, is easier in daylight and with moonlight.
  • May be more nocturnal in areas with high numbers of humans. (Benza et al 2009)
• In Kamberg Nature Reserve, inactive 42% of time; at rest 58% of time; no wet or dry seasonal variation in this pattern. (Perrin & D'Inzillo Carranza 2000)

• Home range area (area used by otter in food-gathering, mating, rearing young) estimated by radio telemetry-tracking at about 6-27 sq km ( 2.3 - 10.4 sq mi) with a core area of about 6 sq km (2.3 sq mi) (Perrin et al 2000)
• Male territories larger than females' and completely overlaps females'. (Perrin et al 2000)

Social organization considered variable; show both solitary and group behaviors, but behavior not well-studied. (Kruuk 2006

• Females with offspring, adolescent groups and male groups are the norm.
• Group size varies according to locality. (Larivière 2002)
  • In Rwanda - most individuals forage alone.
  • In Tanzania - forage in groups of around 3 individuals; solitary individuals rarely seen
• In general, individuals, especially males, forage in groups or packs, acting independently. (Procter 1963)
  • Males have territories and groups of up to 20 individuals (Kruuk 2006)
  • Foraging individuals gather into a pack to cross open spaces to a new foraging area. (Kruuk 2006)
  • Function of packs is not clear - may be protection from predators, especially crocodiles. (Kruuk 2006)

Extremely difficult to identify sex of swimming individuals.

Much mutual grooming but sexes and relationships of grooming individuals not yet well studied.

Researchers note that river otters in Canada (Lontra canadensis) exhibit both social groups and solitary males in the same populations - a highly unusual social organization for mammals. (Blundell et al 2004)

In resource-poor Africa, few telemetry studies of this otter's territorial behavior (Ogada 2004)

• Equipment is expensive; high standards of veterinary care needed for handling animals during implantation.
• Recent study in Kenya of African clawless otter employ non-invasive (no telemetry) methods to study territorial behavior:
  • Scats transferred by researchers from one family's territory to another's territory
  • Resident otter removes scat and deposits fresh scat.
  • Other researchers, however, found otters in Poland did not respond to "invasive" scats. (Brzeziński & Romanowski 2006)

Spot-necked otters are not territorial according to Perrin et al (2000), but this behavior has not been well-studied (Gallant 2007)

• These otters often live in lakes, a more open habitat than a river, possibly requiring territorial behavior that is less definite than that of river-bound species. (Ogada 2004)
• Minimal area needed for a population depends mainly on food availability.
• Individuals defend, however, parts of home range against unknown otters. (Benza et al 2009)

Density of otters on Kamber Nature Reserve in KwaZuluNatal, South Africa: 1 otter/1.6 - 2.4 km (1-1.5 otter/ mi )

One study in KwaZulu-Natal Province indicated that South Africa males have larger home range than females.

• 16 per sq km ( 6.2 per sq mi) - males
• Near 6 per sq km ( 2.3 per sq mi) - females

Females may move far from a shoreline when raising young in a "natal holt" - in order to avoid infanticide by males. (Kruuk 20006)

Aggression

• Females extremely aggressive before birth of cubs--until cubs are active and swimming. (Benza et al 2009)
• Females about to give birth in  managed care often drive out older daughter.
• In managed care, unrelated groups of more than two of these otters cannot be housed together. (Benza et al 2009)

Play and Grooming

• Young otters often play-fight in water in groups of two to five, for several minutes at a time. (Procter 1963) 
• Rivers otters in North America play "hide-and-seek" with a dead fish. (Park 1971).
• Young otters in managed care throw objects into water, attempting to catch them before they hit the bottom. (Rowe-Rowe 1978)
• Groom by rubbing and rolling against grass, rocks, logs to keep fur in good condition and dry. (Benza 2009)
  • Ability to find places for this self-grooming vital for otters' physical and psychological health.

  Visual Signs

• Procter (1963) studied otters at Lake Victoria; noted a possible appeasement behavior:
  • An otter not a member of the local group was seen to approach and "stretch out its neck towards an investigating otter".
  • This gesture seemed to satisfy the resident otters and no conflict was observed.
• Harris (1968) noted North American river otters attempting to make friends with a dog:
  • Advanced "quietly and insinuatingly" towards it with a "singular serpent-like motion of the head and neck."

 Vocalization

• 15 to 20 distinct vocalizations. (Benza et al 2009)
• Three distinct calls noted by Procter (1963) at Lake Victoria.
  • A shrill "chikkering" similar to that of a kingfisher; may be made when playing
  •  A prolonged mewing ya-a-a-a which may be a challenge.
  • A squealing whistle made when excited as in play-fighting.
• A study of six Eurasian otters in managed care recorded otter sounds (Gnoli et al 1998)
  • Whistles uttered by cubs calling mothers, subadults whistle and chitter when having conflicts
  • Hissing occurred often when approaching a human - may be expressing a conflict between interest and fear.
  • Moans uttered with motionless body near ground - may be expressing threat and fear.
  • Cubs whistle to mothers who are far away.
  • Most communications occur on land.
  • Behavioral context can vary for sounds - same sounds can be used in different ways (whistle may be expressing distress or possible offensive threats)

Olfaction/Scent Marking

• Scats (called "spraints") deposited conspicuously on large flat rocks in Lake Victoria; not all researchers see these as merely territorial markers.
  • Otters may be simply "advertising the use of a resource" which might help them forage without competition. (Kruuk 2006)
• Urine sprayed on spraint sites also carries social signals.

On land

• Very agile and at home in water but spend most of their time on land
  • Come out of water to sleep, excrete, give birth, groom, and usually to eat
• Walk, run, gallop on land, but appear awkward (Rowe-Rowe 1978) 
• Can run as fast as a human for short distances
  • Run at 4-5 km/h
  • Front limbs, then rear limbs move together for a "gallop" at 6-7 km/h
• Can stand vertically on hind limbs (Larivière 2002)
  • Easily climb rocks and trees and scale fences
  • Jump at least across a 1 m (3 ft) gap
• Do not travel significant distances overland, as do other otter species (Reed-Smith 2009)
• Dig burrows/nests/shelters when soil is suitable (Rowe-Smith 2009)

In water

• Can swim 0.4 km (0.3 mi) underwater (Harris 1968) at 1 m/sec (2 mph) (Mortimer 1963)
• Known to swim distances up to 7 miles
• Hind limbs provide thrust for swimming
• Front limbs held close to body and used for turning
• Tail adds balance

Coexists with, but doesn't compete directly with:

• Cape (African) clawless otters (Aonyx capensis)
• Congo clawless otter (Aonyx congicus)
• Water mongooses (Atilax paludinosus) during drought conditions in eastern Cape Province, South Africa along the Bushmans River. (Somers & Purves 1996) (Rowe-Rowe & Sommers 1998)

Presence of spot-necked otters signals absence of Nile crocodiles in a habitat. (Lejeune & Frank 1990)

Take portions of fish catch of local Rwandans. (Larivière 2002)

Spot-necked otter investigates a pumpkin, as part of the San Diego Zoo's animal welfare enrichment programs.

Image credit: © San Diego Zoo Wildlife Alliance. All rights reserved.

Benza et al (2009)
Blundell et al (2004)
Brzeziński & Romanowski (2006)
Gallant (2007)
Gnoli et al (1998)
Harris (1968)
Kruuk (2006)
Larivière (2002)
Lejeune & Frank (1990)
Ogada (2004)
Park (1971)
Perrin et al (2000)
Perrin & D'Inzillo Carranza (2000)
Procter (1963)
Rowe-Rowe (1978, 1992)
Rowe-Rowe & Sommers (1998)
Somers & Purves (1996)