Elephants are the largest land mammals on earth, and big
animals need lots of space. We know that
elephants migrate annually to find food and water, and that the matriarchs lead
their herds from year to year (learn more by reading previous entries in our
blog!). However, the full migratory
paths of both Asian and African elephants is neither well studied nor well
known. There are a number of challenges
in studying these routes, from overcoming technological hurdles to combating bureaucratic
red tape.
Many elephants need many resources. Photo by Rebecca Shoer
Elephants
require large migratory ranges for a
number of reasons. Most obviously, they
consume huge amounts of food every day, and must move when an area's resources
are depleted. In addition, female and
male elephants have almost entirely separate social lives, and migrate
independently of one another (and thus their migratory routes rarely overlap). Male elephants may travel alone or in loose
bachelor herds, but obviously must return to a female herd to mate. What is the typical range for an elephant,
then? It seems to vary over
subpopulations of elephants, but some estimates have been made, especially in
India:
Home ranges of over 600 km² have been recorded for
females in south India (Baskaran et al., 1995). In
north India, female home ranges of 184–326 km² and male home ranges of 188–407 km² have been recorded (Williams,
2002). Smaller home range sizes, 30–160 km² for females and 53–345 km² for males, have been recorded in Sri
Lanka (Fernando et al.,
2005).
(IUCN Red List)
(IUCN Red List)
However, such estimates are few
and far between, and most research has been done in few select areas of
Asia. Why is this? First of all, Asian
elephants live in a mixed habitat of grassland and jungle, making them quite
difficult to locate and track in the wild.
Some African elephants have been micro-chipped or radio collared so that
they might be tracked, but these devices are both expensive to purchase and
require a veterinarian to install safely. Second,
as elephants have such large home ranges, they inevitably cross human-created
borders, either between states or countries.
This creates a challenge for both the migrating elephants and the
researchers attempting to track them. In
1999 "The Old Elephant Route" project was started in the Patkai
Range, along the border of India and Myanmar (Burma) to assess the range and
activity use of this known migratory corridor (Chowta et al). Unfortunately, the project suffered constant setbacks
due to the political situation in Myanmar.
Although they were eventually able to gather enough data through India
to map the migration patterns of some elephants, they still had to struggle
both with hauling equipment in the wilderness and recruiting volunteers during
a time of political turmoil.
Modified from the Aane Mane Foundation
Finally,
the major obstacle in studying elephant migration is the tremendous level of
habitat loss that has occurred and is still occurring in southeast Asia. Even if elephants still attempt to follow
their traditional migration routes, they have to traverse over farmland,
through villages, and across roads. In
northern India, a highway was constructed in 2009 that directly cut through a
four mile wide known migratory corridor (Novak, 2009). This corridor served as the only route by
which the roughly 1,000 elephants residing in that region could access a
critical water source. In Thailand, only
15% of the natural forest still remains, and the 3,000 wild elephants that
still live in the country are isolated in national parks. Even if we were able to track their migration
routes, such routes have most likely been so altered due to human influence
that the elephants no longer traverse the large areas they once did. However, in countries like India where both
large wild elephant populations and large natural areas still exist, it is
critical that we identify where these elephants travel in order to protect
those areas from human development. It
is not enough to protect areas that elephants may be in today, or tomorrow, but
the entire area that an elephant may use in an entire year. Unfortunately, this is rapidly becoming a
remote possibility in southeast Asia, as the human population continues to
increase. The urgency of the elephant's
situation cannot be overstated.
Sources
Novak, Sara. 2009. "The Plight of the Asian
Elephant--New Highway Checkpoint Threatens to Cut Off Elephant Life Line."
www.treehugger.com
Chowta, P. 2010. "The Old Elephant Route." Aane Mane Foundation. www.aanemane.org
Choudhury, A.,
Lahiri Choudhury, D.K., Desai, A., Duckworth, J.W., Easa, P.S., Johnsingh,
A.J.T., Fernando, P., Hedges, S., Gunawardena, M., Kurt, F., Karanth, U.,
Lister, A., Menon, V., Riddle, H., Rübel, A. & Wikramanayake, E. (IUCN SSC
Asian Elephant Specialist Group) 2008. Elephas
maximus. In: IUCN 2013. IUCN Red List of Threatened Species. Version
2013.1. <www.iucnredlist.org>.