Martes americana - American Marten

Skull Pictures:       
Dorsal     Posterior mandible
Lateral     Ventral
Mandible

Physical Description:

The American marten (Martes americana) is commonly referred to as the American marten or the pine marten.  This carnivore is a member of the family mustelidae.  It resembles a small house cat with shorter legs, a bushy tail, and a more slender body with dark brown fur.  Martens show sexual dimorphism with the males generally slightly larger than the females (Smith and Schaefer 2002).

Fossil History and Distribution:

Marten fossils do not appear until the middle Pliocene in Poland.  The subgenus Martes did not appear in North America until the late Pliocene (Stone and Cook).  The marten usually inhabits relatively unfragmented mature coniferous forests but is sometimes also found in mixed conifer/deciduous forests.  It is found throughout Canada’s and Alaska’s forested regions.  They are also found in the northern part of the United States such as Minnesota, Maine, and New York, and in the Rocky Mountains (Kurta 2001).  Before the logging movement, northern Wisconsin had optimal habitat for martens.  Trapping and habitat destruction in the form of logging led to the extirpation of the marten in Wisconsin by 1939 and has led to a decline in their numbers and distribution throughout their range.  Between 1975 and 1983, the Wisconsin Department of Natural Resources and the U.S. Forest Service released 172 marten in the Nicolet Forest in northeastern Wisconsin.  Between 1987 and 1990, the Wisconsin DNR released 139 more animals in the Chequamegon National Forest in the northwestern part of the state (Wisconsin DNR).  These two populations remain separate and DNR estimates put the current population size at 500 to 1000 animals (Fig. 1).  However, there is evidence that the population in the northwest is declining.  But, with limited surveying and data, it is still uncertain.  Winter DNR surveys in 2004 should reveal more about their ranges and population sizes in Wisconsin.

Figure 1.  Marten Distribution in Wisconsin (Wisconsin Department of Natural Resources accessed October 21, 2003).

Ontogeny and Reproduction:

Martens do not reproduce until they are two years old. They mate in July or August but experience delayed implantation and development of the embryo stops until the beginning of March.  Young are born in late March or April.  Litter size is usually 2-3 (Kurta 2001).  They are weaned at 6-7 weeks and disperse and set up their own territories in the fall (Wisconsin Department of Natural Resources). 

Ecology and Behavior:

Martens are generally nocturnal.  Their nocturnal activity is thought to help them avoid predation, especially from avian predators.  However, martens in the northern part of their range may be diurnal during the winter.  Although martens live in relatively cold climates, they have few morphological or physiological adaptations to the cold and this daytime activity for those in the north helps them avoid the cold temperatures in winter  (Drew and Bissonette 1997).

Martens will become inactive either because of extreme cold or because of the high cost of locomotion after a heavy snowfall.  The most thermally efficient place for marten to remain inactive is below the snow (subnivean).  Forests that have a lot of coarse woody debris or lower branches on or near the ground provide access to subnivean resting locations by creating air pockets in the snow.  Martens in winter prefer to rest in subnivean locations, but they may also rest in trees, usually conifers (Wilbert et al. 2000).   In addition martens rest in logs, rock crevices, and any other spot that offers them concealment (Ruggiero et al. 1998).  

Martens are carnivorous. They hunt primarily subnivean (Drew and Bissonette 1997).  The coarse woody debris that they use for denning and resting is also where they spend much of their time hunting for small mammals.  Although voles and other small mammals seem to be the most common prey items, it is the grouse, squirrels, and snowshoe hares that make up the vast majority of calories consumed and consequently energy intake.  They will also eat fruit, insects, and vegetation, although more commonly in the summer (Cumberland et al. 2001).

Its home range size is about 1 km2 for females and about 2-4 km2 for males (Kurta 2001).

Remarks:

The marten is well established in the neighboring state of Minnesota as well as northeast states like Maine.  These states have a habitat similar to Wisconsin, yet in Wisconsin the population is struggling.  The reason for this is still undetermined.  Currently, the two core areas where marten live in Wisconsin are closed to dry land trapping in order to avoid accidental marten catches by trappers and help the population to get established.

Marten are still trapped for their fur throughout Canada and in a few states in the United States.

Literature Cited:

Cumberland, R.E., J.A. Dempsy, and G.J. Forbes.  2001.  Should diet be based on biomass?  Importance of larger prey to the American marten.  Wildlife Society Bulletin, 29(4): 1125-1130.

Drew, S.G., and J.A. Bissonette.  1997  Winter Activity patterns of American martens (Martes americana): rejection of the hypothesis of thermal-cost minimization.  Canadian Journal of Zoology, 75(5) 812-816.

Kurta, A.  2001.  Mammals of the Great Lakes Region: 223-226.  University of Michigan Press.

Ruggiero, L.F., D.E. Pearson, and S.E. Henry.  1998.  Characteristics of American marten den sites in Wyoming.  Journal of Wildlife Management 62(2): 663-673.

Smith, A.C., and J.A. Schaefer.  2002.  Home range size and habitat selection by American Marten (Martes Americana) in Labrador.  Canadian Journal of Zoology  80(9): 1602-1609.

Stone, K.D., and J.A. Cook.  Molecular evolution of Holarctic martens (genus Martes, Mammalia: Carnivora: Mustelidae).  http://www.sou.edu/biology/Faculty/Stone/images/Molecular%20evolution%   20of%20martens.pdf Accessed 23 October 2003.

Wilbert, C.J., S.W. Burskirk, and K.G. Gerow.  2000.  Effects of weather and snow on habitat selection of American martens (Martes americana).  Canadian Journal of Zoology 78(10): 1691-1696.

Wisconsin Department of Natural Resources.  American Marten.  http://www.dnr.state.wi.us/org/land/er/factsheets/mammals/Marten.htm  Accessed 23 October 2003.

Reference written by Troy Radtke, Biology 378 student.  Edited by Christopher Yahnke.
Page last updated 4- 27-04.