The Alpha Mom

          Pokémon© will always be a childhood favorite and has yet to cease expanding its world. Beyond the “original 151,” a certain duo originates from a very real biological relationship. Seviper easily resembles a large snake. Zangoose is an interesting mosaic of cat and mongoose-like qualities. Their ongoing interspecies feud is largely fueled by the antagonist relationship between snakes and mongooses in the wild. Mongooses are one of the few animals that can fight back against snakes due to their relative immunity to the neurotoxins (Remulondi and Zengeya 2014).

          What about the small fry though? Mongooses is a collective group of several species. While the animated creature is cool, we should devote some attention to the littles ones too. Enter the dwarf mongoose, the smallest mongoose species and the smallest carnivore in Africa. Its scientific name is Helogale parvula. Its common name varies across languages and regions. Besides its cute size, the dwarf mongoose is characterized by its rounded ears, short muzzle, and long tail. Fur color across populations is usually a reddish-brown buff, sometimes speckled with black or gray (WAZA). Body weight ranges between 210 and 350 grams (0.5-1 pounds) and length or height varies between 18 and 30 centimeters (0.5-1 feet). Dwarf mongooses can live to an average age of 10 to 14 years in the wild or up to 18 years in captivity (Ramulondi and Zengeya 2014).

img_7069
A pack sleeping in a hollow log. Fake termite mounds are visible in the back. Taken at the Lincoln Park Zoo in Chicago, IL.

 

          These small-bodied mammals are diurnal and have extremely good eyesight. They are mostly insectivorous but are known to be indiscriminate carnivores. Rodents, lizards, and even some snakes are viable food sources. While scavenging for insects like termites, the mongooses may use old termite mounds as dens. If not available, they can utilize hollow logs or rock crevices as well. Groups will never stay in one place for too long and prefer to rotate between dens in the territory every few days. This helps minimize predation risk as their position while sleeping and vulnerable is less predictable (Ramulondi and Zengeya 2014).

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.          Dwarf mongooses cover a huge geographical range in Africa. Populations have been found as high north as Ethiopia and southern Somali all the way down the east coast to Mozambique in South Africa. Their range also extends over parts of central Africa from Angola on the west coast to Malawi in the east. The most common habitats are forests, woodlands, savannas, and other semi-arid areas. A habitat cannot be too thick, dense, or dry however. Populations have been found at elevations of up to 2000 meters in more mountainous regions. Since dwarf mongooses are so widespread and sometimes reach high densities even in protected preserves, they are marked under “Least Concern” in terms of conservation. Despite their commonality, they are still victim to hunting. Some indigenous cultures desire their meat. Other times they are shot for being pests; farmers often blame the mongooses for stealing eggs (Sharpe et al. 2015).

iucn-habitat-range
Native range of the dwarf mongoose, shaded in orange. The conservation status is shown on the right. Taken from the IUCN Red List.

          The really interesting characteristic of dwarf mongooses is their reversed hierarchical social structure. It is common for species to have a dominant male breeding with several females and the older members of a group are higher in rank than others. Mongooses are a bit unusual. They live in groups of up to 30 members called packs or mobs. The packs are matriarchal and largely cooperative. All members of a group are most likely related and often times will be the children of the alpha female. The youngest members are highest in rank below the alpha mongooses and will subsequently be demoted when the next generation is born. The older siblings will help rear the young by feeding them milk or foraging for insects, grooming them, and playing with them. This odd hierarchy might be a mechanism for ensuring a high survival rate of the alpha’s young (WAZA).

          As previously mentioned, mongoose packs are matriarchal. An alpha female will breed with one male and together they are the top ranking pair in the whole group. The alpha female has a gestation period of about 50 to 60 days. She can produce two to four litters per year, each consisting of four to six pups. Every successive batch of offspring becomes the next highest ranking mongooses under the alpha pair. The rest of their siblings get pushed down the hierarchy and are fixed with babysitting duty. Aside from the alpha pair, all other sexually mature mongooses in the pack are subordinates. While some do successfully mate and breed, their young do not have high survival rates (Ramulondi and Zengeya 2014).

          Subordinate mating is greatly suppressed in packs. Females are both hormonally and behaviorally suppressed. The alpha female will often interrupt mating. Creel et al. (1992) show that baseline and peak estrogen levels are relatively low in subordinate females compared to the matriarch. Estrogen is a hormone important for stimulating the female reproductive system, preparing it for fertilization and pregnancy. Males were found to be behaviorally suppressed. Subordinate males attempting to mate were often subject to aggressive attacks by the alpha male. Their androgen levels however were kept around baseline.

          Another study by Rood (1990) looked at subordinate members rising to alpha status. One possibility is to succeed the alpha pair in a natal pack. More often though, subordinate members would emigrate. Males could potentially oust an alpha male from an existing pack. Emigrating females and males could found a new pack and thus become the alpha breeding pair. Emigration and founding of new packs seemed to be a faster mode of becoming alphas than succession within the natal pack.

img_7086          Last but not least, dwarf mongooses are not only extremely cooperative within the pack but have complex behaviors and a network of relationships with other organisms. Within the pack, there is great organization for foraging. Often times, experienced older members are put on rotating sentry duty to look out for predators while the younger members forage with low vigilance. Depending on the predator, the sentries will give various alert calls to the pack. The sound for an aerial predator like birds of prey (goshawks and eagles) is different from one for a large terrestrial carnivore like jackals. There is also another call for predators more like snakes hiding in the grasses. Beyond predation, the mongooses even have calls for playing with young or notifying others of a food resource. Dwarf mongooses also have mutualistic relationships. The hornbill will share a den with the mongooses. They both benefit from alarm calls and feeding. Giant scaled lizards help keep the dens hygienic by eating the mongooses feces (Ramulondi and Zengeya 2014).

         On that elegant note, I hope readers everywhere have gained an appreciation for these furry, tiny, hardworking, social animals in the scope of all vertebrate diversity. Cheers to the dwarf mongoose!


References

Creel, S., Creel, N., Wildt, D. E., Monfort, S. L. 1992. Behavioural and endocrine mechanisms of reproductive suppression in Serenge dwarf mongooses. Animal Behaviour. Volume 43, Issue 2, Pages 231-245. ISSN 0003-3472, http://dx.doi.org/10.1016/S0003-3472(05)80219-2. (http://www.sciencedirect.com/science/article/pii/S0003347205802192)

Rood, J. P. 1990. Group size, survival, reproduction, and routes to breeding in dwarf mongooses. Animal Behaviour. Volume 39, Issue 3, Pages 566-572. ISSN 0003-3472, http://dx.doi.org/10.1016/S0003-3472(05)80423-3. (http://www.sciencedirect.com/science/article/pii/S0003347205804233)

Ramulondi, E., and Zengeya, T. 2014. Dwarf Mongoose. Retrieved December 10, 2016, from http://www.sanbi.org/creature/dwarf-mongoose

Sharpe, L., Kern, J. and Do Linh San, E. 2015. Helogale parvula. The IUCN Red List of Threatened Species 2015: e.T41609A45206516. http://dx.doi.org/10.2305/IUCN.UK.2015-4.RLTS.T41609A45206516.en. Downloaded on 07 December 2016.

WAZA. (n.d.). Dwarf Mongoose. Retrieved December 10, 2016, from http://www.waza.org/en/zoo/visit-the-zoo/small-carnivores-1254385523/helogale-parvula

*All photos taken personally at the Lincoln Park Zoo in Chicago, IL

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