Bobcat Population Dynamics, Distribution,
& Landscapte Genetics

Bobcat
ISU

William R. Clark, Ph.D. & Todd Gosselink, Ph.D.

IOWA STATE UNIVERSITY

Iowa Department of Natural Resources

IDNR
Reproduction, Survival, and Dispersal
Reproduction

Bobcats may begin breeding as early as February but most breeding in Iowa takes place in March through April. Females give birth about 60 days later to a litter of 3 or 4 kittens so therefore most young are born in April to June. It is extremely rare for yearling females to give birth, about 60% of the 2-year-old females give birth, whereas about 80-85% of females 3 years old or older give birth to a litter each year. By intensively monitoring 14 radio-collared female bobcats we found that large brush piles and areas of dense understory vegetation are typically used as den sites. Kittens will stay near their mother for up to a year (image right -like domestic cats, bobcat kittens are helpless when born and open their eyes at about 10 days).

Survival

We have estimated the annual survival rate of bobcats from both the radio-collar data and also from the age structure of the carcass collections. The radio-collar data revealed a surprising pattern with average annual survival of 1-2 year old bobcats of about 77% which was actually greater than older individuals with survival estimated to be about 60%. This is probably due to the fact that over 80% of the mortality is human-caused including incidental trapping, illegal activity, automobile collision, and legal harvest (figure to right). The age structure data (figure to left) also highlights that very few bobcats live to age 5. The oldest bobcat we aged was 13 years old. Accounting for the variation in the observed age structure and reproductive rates we estimated that the southern Iowa population is increasing at about 8.5% per year. Iowa’s first regulated harvest season was opened in 2007 and the open zone now includes 35 counties. Based on distribution estimated from the bowhunter observation survey (see Statewide Distribution) we estimated a population of about 2800 bobcats in the open zone and perhaps about 3500 bobcats in all of Iowa. The DNR used these estimates to set regulations including the harvest quota.

Dispersal:
Dispersal Map

Young bobcats (<2 years old) move out of the area where they were born. Based on records for over 22 individual radioed collared bobcats, female bobcats dispersed an average of about 17 miles whereas males moved over 50 miles. The maximum straight-line dispersal distance that we have observed by a collared bobcat is that of a male that dispersed 154 miles. Although dispersal typically begins in late winter/early spring we have documented continuous roaming behavior of males for as long as 3 years. Many collared bobcats have moved out of Iowa and into the adjacent states of Missouri and Nebraska.

Background | Methods | Description, Tracks, & Food Habits | Habitat Use & Social Structure | Reproduction, Survival, & Dispersal | Statewide Distribution | Population Genetics | Outreach, Collaborators, & Funding |
Report | Bobcat Homepage | Dr. Clark Homepage

Department of Ecology, Evolution, and Organismal Biology
Ecology and Evolutionary Biology

Updated 08/29/2011