~ This page was made as part of an undergraduate course at Davidson College ~
Social Relationships
Two dwarf mongooses (probably the alpha male and female) hanging out together [Photo courtesy of Fred Voetsch Publishing, Permission pending].
Who mates with whom?
Only the dominant female and the dominant male are allowed to breed. They are a monogamous pair. Sometimes, however, extra-pair copulations do occur. If it does occur and if the copulation results in pregnancy, the children rarely, if ever, survive.
Why monogamy?
Dwarf mongooses are special because they are one of the less than 3% of mammalian species reported to be monogamous. Among the monogamous animals, there are two forms of monogamy: facultative and obligate. Dwarf mongooses are involved in obligate monogamy, which occurs because the female cannot rear her litter without help, but the carrying capacity of the habitat is limited such that only one female in a pack can breed at a time. As a result of their monogamy, Dwarf mongooses display little sexual dimorphism (physically or behaviorally), and they exhibit infrequent socio-sexual interactions beyond the early stages of pair bond formation. In captive or close field observations, dwarf mongooses show that the heterosexual pair is tolerant and will cohabitate at all times, the pair will breed and remain together during the rearing phase without fighting, and male of the pair will participate in aggressive behavior (Kleiman). Behaviorally, this exclusive monogamy results in the alpha males protecting the alpha females in the early stages of estrus—he remains close to her, copulates with her exclusively, and will attack any adult males that approach her (Rood, 1980).
Why is no one else
permitted to mate?
The alpha female involves herself in breeding suppression. Breeding suppression occurs when the alpha female somehow prevents the subordinate females from mating and/or reproducing. The mechanism of breeding suppression in dwarf mongooses is not currently known. Non-dominant females come into estrus in synchrony with the alpha female; while some of these non-dominant females may get pregnant, they are not permitted to raise their offspring. If they do become visibly pregnant, they are believed to abort the fetus. Therefore, the alpha male and alpha male are likely to be the parents of most young born in the pack; only about 15-20% of offspring belong to subordinate males or subordinate females. Packs of dwarf mongooses are very cooperative and display apparently altruistic behavior. Females that helped were related to the young they were nursing and would thereby benefit from inclusive fitness. Use this for the cooperation section.
Does monogamy effect aggression levels within males in dwarf mongooses?
Usually in monogamous pairs, there is a high level of paternal care; therefore, testosterone levels should increase above the breeding baseline if and only if aggression is triggered. Aggression occurred during mating periods as well as immigration events (especially with unsuccessful immigrants and males warding off immigrants). This theory does not hold true with Dwarf Mongooses (androgen levels did not increase during periods of mating and aggression). Why? Perhaps because the multimale/ multifemale breeding group complexity has an effect on androgen levels; even though they are monogamous, their social organization must be taken into consideration (Creel et al.).
What is it like when the alpha female gives birth?
The breeding season is during the rainy season (from November to May) and gestation lasts about 49 to 56 days (Sorin). The alpha female produces about 3 litters a year, with an average of 2 to 4 dwarf mongooses per litter. While alpha females do lactate, they do not feed milk to the newborns. However, subordinate females were also observed to be lactating upon the birth of a litter, even when they did not become visibly pregnant, in synchrony with the alpha female (Rood, 1980).
What happens with the kids after they're born?
Young are baby-sat at the nest until they are about 6 months of age, at which time they begin to forage with the rest of the pack. The young reach full sexual maturity at around 3 years of age (Sorin).
Are there any strong bonds outside the monogamy?
Dwarf mongooses are very social animals. They strengthen their bonds with behaviors that are unusual to mammals, such as play. Play vocalizations are motivation-specific; the number of pulses per second had positive correlation with play intensity. An average play session will last 4.8 to 16.2 minutes.
1. Play becomes fragmented prior to termination
2. Motivations changes during a session fall into 3 different patterns all terminating at a given point
3. Behavioral patterns performed during play are causally different from those of exploration and have “optimum intensities.”
4. Higher intensity play involves more limbs used in object manipulation
5. Higher intensity play involves more play behavioral patterns per given time period.
In dwarf mongooses, play is an instinctual behavior that is its own motivation. Play vocalization probably evolved b/c of the dm’s lack of ability for facial and bodily expressions (Rasa, 1984).