In
summary, Desmodus rotundus is a very interesting animal.
The promiscuous mating system and home range is the best fit for the life style
of the vampire bat. The interesting spacial relationship of the food and
the roosting sites are the main reason for the promiscuous mating system.
The vampire bats are such small animals, and they roost in such large spaces and
feed on large prey. They are forced to aggregate into large groups while
roosting and will come in contact with other bats while feeding. Therefore,
the home range social spacing works well because the individual bats will be coming
in contact with each other for the most part of every day and there is less
aggression between members of the species during these encounters. This
is beneficial because they will not waste energy nor risk injury by high aggression
encounters. This close interaction in the roost then lends towards promiscuous
behavior because there are so many females near each other that the males benefit
more from mating with multiple females, and the females benefit from being able
to mate with multiple males. There are not many major selection pressures
on the vampire bat. The only pressure is finding a location to roost.
The food supply is continually increasing as the number of farms and ranches increases,
and there remains low predation. The farmers have as of now proved to be
relatively ineffectual in attempting to kill off vampire bats near their properties.
Thus, the number of vampire bats will continue to increase as time goes on.