Mating
Photo by Jennifer Jarvis/University of Cape Town
http://www.news.cornell.edu/releases/Aug99/rat_mamm.hrs.html
Breeding
The queen is the only breeding female in the colony, in addition to being social the most dominant, she is also physically different than other females in the colony. She is larger and has a noticeably elongated body, she is also the only fully sexually developed female in the colony. Her vagina is perforate or nearly so while other colony females’ vaginas are closed, she also has the most developed teats of the colony females. The other females in the colony are not sterile and can quickly become reproductively active when the queen is removed or they are moved to a solitary cage. While there is only one breeding female there can be between one and three breeding males. The queen and the breeding males can maintain their breeding positions for a long time, in some cases the breeders have held their position for over eight years (Jarvis 1991).
The queen has a behavioral estrus of 2-24 hours where she mates repeatedly
with the breeding male or males. Mating usually occurs in the tunnels which
makes it easier for the male to stay on top of the female (Jarvis 1991).
Mating is usually initiated by the female (68% of the time). Also
late in
pregnancy naked mole-rats engage in mounting, the purpose of which is unknown.
Breeding males and females frequently engage in ano-genital nuzzling. Just
prior to giving birth the queen will run quickly through the burrow. The
queen usually gives birth to approximately ten pups (but as many as 27
have been
recorded) after a gestation of approximately 70 days. The queen will mate
again 8-1l days after giving birth, meaning that she can have four to five
litters
a year. Many members of the colony help in raising the pups (Lacey et al.,
1991).
Succession
While the queen is in “power” as the
dominant female, aggression between females in generally limited.
During this time the
other females are reproductively suppressed, but following the removal of the
queen several females can come into estrus at once. Also several females will
frequently start engaging in shoving, or shoving more often than they did
previously trying to establish
themselves as dominant. These females, which are high ranking, large females
will often fight to become the sole breeding female in the colony, this can
result in a series of fights that can be spread out over several month and
usually result in the death of at least one of the combatants. In other cases
there will be no fighting and another female will become queen very smoothly
(Margulis et al., 1995).
This web site was completed in partial fulfillment of the requiremtns for Biology 323, Animal Behavior at Davidson College in the Spring Semester of 2003.