the 'Dhole'

[X99Lynx at aol.com]

I wrote:

<<Dholes (aka "red dog of India" (Kipling)) are found in dense forests.  Wolves
as a general rule and apparently especially in southern Asia are found in open
habitats.>>

In a message dated 7/1/01 10:52:51 PM, dlwhite at texas.net writes:

<<Just briefly, again... No.  Wolves used to live in eastern N. America, not
to mention Japan, which is not exactly noted for its open steppes, and dholes
occurred in the tundra environments of Ice Age Europe.  >>

Just briefly again,... yes.  Or, mostly yes.
- I should have written "Wolves as a general rule and apparently especially
in southern Asia are found in MORE open habitats than the dhole."  I also
assume we are speaking of the grey wolf, as other kinds of "wolves" may be
more distant in descent than the dhole.

- A quick search on the web will return many, many repetitions of the
statement that "Wolves do not live in" or "are seldom found in arid deserts
or tropical forests."

- The basic problem with the "southern heat and humidity" idea may be that in
fact the Indian Wolf, a subspecies of canis lupus, is found "south down the
middle of India towards Madras and Bangalore."  See a map of its range to the
deep south of the subcontinent at
http://www.myinternet.co.uk/wsgb/education/newsletters/archive/winter2000.htm.
Also, according to the WSGB, "Wolves in India tend to prefer open habitat,
usually scrubland, avoiding forested areas. This is possibly an adaptation to
avoid competition with big cats such as tigers and leopards, and the Asian
wild dog or dhole, although wolf populations do sometimes overlap leopard
territories.  [An alternative explanation is that] wolves may have initially
arrived in India from the arid areas of the Middle East and naturally
colonised open habitat rather than the moister forests."  An analogy is also
draw to the adpative behavior of the Ethiopian wolf, which inhabits
relatively high, treeless ground exclusively.

- Recent studies (e.g., Helen Purves and Carol Doering, Wolves and People:
Assessing cumulative impacts of human disturbance on wolves in Jasper
National Park, 1999) tend to show that the best indicators of wolf movement
and habitat are prey biomass concentration, "least-cost paths" and avoidance
of human development areas.
Although tropical forests are extremely rich in prey, movement in them tends
to be difficult and inefficient for the particular predation style of the
wolf - as with other heavily obstructed areas such as bouldered areas, salt
marshes and steeper slopes.  And this "least cost" analysis would seem to be
the best explanation for the otherwise ubiqutous wolf's relative absence from
many dense tropical and sub-tropical forest environments.

- The dhole by all accounts favors dense forests, especially tropical and
sub-tropical forests. ("In the Soviet Union, the dhole inhabits alpine areas
and dense forests; in India, dense forest and thick scrub jungle up to
2,100m; in Thailand, dense montane forest up to 3,000m.") Such specialized
adaption could not have been recent.  I didn't find any clear references to
the dhole inhabiting "open steppes" or "tundra" environments; some evidence
from the late Pleistocene also seems to locate the dhole in thickly forested
environments (e.g., Ovodov, 1977).  If there were "dholes" on the open
steppes in those days, the first impression might be that they were
materially and taxonomically distinct from the main branch of the species.

-  The best evidence we have perhaps is that the dholes's more modern
environment has been determined by the natural and human-induced shrinkage of
its primary environment.  According to the World Conservation Union, the
major factors affecting the dholes range have been (note the final reference
to wolves):

"In India, disease appears to be important in population regulation. In C.a.
 primaevus, virulent distemper, rabies, or both are thought to kill dholes
 periodically in Chitawan and Corbett. The prey base in these areas suggests
 that these should be among the best dhole habitats in this subspecies' range.
 Their rarity in this region may be due to natural causes, or may be the
 result of increased human contact (and contact with domestic dogs) leading to
 frequent disease introductions.
 2.  C. a. dukhunensis: Two forms of disturbance within reserves by local
 people: stealing of kills; and disturbance at den sites during the breeding
 season leading to den shifting and possible pup mortality. Threats in outside
 reserves include poisoning, resulting from conflicts with cattle grazers and
 depletion of natural prey (Axis axis, Cervus unicolor) by poachers (Johnsingh
 1986).
 3.  Declines in populations for "unexplained" reasons have been documented in
 Kanha and the Soviet Union. In the Soviet Union, reasons for decline after
 1920 are uniformly uncertain.... Ovsyanikov suggests that poison bait
 programmes aimed at elimination of wolves, Canis lupus, may have
 inadvertently eliminated dholes in areas in which the two species overlap."

There's good reason to think that the dhole developed as a specialized
adaption to dense forest environments and its distribution has not been
particularly affected by the wolf - as it does not appear to be particularly
affected by tigers or bears.  On the other hand, the wolf's relative absence
from typical dhole habitats can also be explained in much more obvious and
universally applicable ways.  Nothing suggests anything like the innate
superiority of the wolf.

Finally, I cannot find anything that attributes the distribution of the wolf
being affected by heat or humidity.

<<Note that wolves have not spread from temperate N. America into tropical
Central America either, despite there being no competition there from dholes
or anything else of the sort.>>

Not that it has anything to do with the wolf's range in that region, but the
Mayan military class called themselves by the name of a predator in the
neighborhood that is quite capable of being thought as "competition" - the
jaguar.  But then again, there were sabre-tooth tigers and wolves living
alongside of one another in Florida @10,000 years ago.  Perhaps the ocean air
canceled out the humidity.

Regards,
Steve Long