Bobcat Ecology

The Bobcat (Lynx rufus floridanus) is a warm-blooded, solitary, and territorial predator mammal. It is one of two species of felines which can currently be found in wild Florida. The other species is the Florida panther (Felis concolor coryi). Not as big as a panther, but about the size of a medium-sized dog, male and female bobcats average 99 cm (39 in.) and 92 cm (36 in) in length, and 11 kg (24 lb.) and 7 kg (15 lb.) in weight, respectively. They are most easily identified by their short tails which are about 14 cm (5.5 in.). Their fur is short, soft, and dense. Its color is dark brown with black spots and bars most visible along the sides and legs. The backs of their ears are white with a black outline. Their underparts are generally white.

Bobcats can most likely be found in every county in Florida and in most states in the country. Looking similar in appearance and genetically related to the Canadian lynx (Lynx canadensis.), the northern end of the bobcat's range slightly overlaps with the southern end of the lynx range near the Canadian border. Compared to a lynx, a bobcat has shorter legs and smaller feet. Due to its abundance in Florida, the bobcat is not listed as endangered nor threatened. However, it is classified as a fur-bearing game animal by the Florida Game and Freshwater Fish Commission and can only be hunted during certain months of the year.

A radio-collared bobcat being released. Radio-collar research has provided the means by which we have learned most of what is known about bobcat ecology, as presented on this web page. Collars neither harm the animal nor in any way impede any of its abilities. In fact, in addition to being invaluable tools for understanding how animals live in the wild and providing a means of obtaining information essential for the management of their long term persistence, radio-collars also enable researchers to locate and rescue animals which are sick or injured.

A bobcat watching the author on the Merritt Island National Wildlife Refuge.

SOCIAL STRUCTURE AND HOME RANGES

Bobcats are territorial and solitary. Each adult maintains and defends an intrasexually exclusive home range. By intrasexual exclusiveness, it is meant that bobcats of the same sex do not share the same home range. A male bobcat will not allow another male to use its home range. Likewise, a female bobcat will not tolerate another female within her range. However, there is some overlap in range boundaries between same-sexed neighbors. Furthermore, the degree of overlap varies from area to area and by sex.

Males do allow females to use their ranges and vice-versa. This is what is referred to as intersexual (between sexes) coexistence. Because of this territorial behavior, bobcat property is partitioned in much the same way as humans own and occupy property. Social interactions among bobcats are infrequent and brief. Except when adults come together to mate, or when a female is raising kittens, each bobcat remains alone throughout its life.

Male home range sizes average 4900 acres and female ranges average 2900 acres. However, home range sizes for both sexes vary from area to area and strongly depend on the enclosed quality of habitats and prey availability. In general, the higher the quality of habitats, the higher the prey densities, and the smaller the bobcat home ranges. Because female ranges are smaller than male ranges, a male has access to two or more females in his range with which he can mate.

Home ranges are elliptical in shape and boundaries often follow roads, streams, or other natural contours. Boundaries, as well as range sizes, do shift seasonally. For instance, males tend to expand their boundaries during the breeding season in order to maximize the opportunities to find a mate. When rearing young kittens, females often appear to use less area because of the need to tend to their litter. Sometimes, an adult bobcat will expand or shift its range into an adjacent range if that adjacent resident adult has died. A transient adult (one without a well defined home range) or dispersing subadult can also occupy a recently vacated range.

Typical bobcat densities in Florida, which reflect home range sizes, habitat quality, and prey availability, are on the order of 80 adults, juveniles, and kittens per 100 square miles. But they do vary from area to area, and through time. The density of a population may also dictate the degree of overlap between adjacent same sexed ranges. Territoriality may occur only during conditions of low densities. In this case, a population would exhibit large home ranges and very little home range overlap.

BREEDING

Mating usually occurs from the late fall to early winter. Courtship and mating usually last one to two days. During this time, the male and female will travel, hunt, and eat together. After mating, the pair will separate and go their separate ways. Mating is the only time that adult bobcats are together. Hence, bobcats are solitary.

Gestation lasts about 63 days, after which a female gives birth to two or three kittens. Births usually peak in the late winter or early spring. However, matings and births can occur in any month of the year. Litter size and pregnancy rate may depend on the age of the female and the availability of prey. Kittens will nurse from the dam (mother) for about two months, after which they will be introduced to solid food. From about five months on, the dam will teach her kittens how to hunt for food. From eight to eleven months of age, the dam will abandon her kittens and/or evict them from her home range. She probably does this because she has become pregnant with a new litter and does not want her older kittens from the previous year to harm her new kittens when they are born. The resident adult male of her range also often chases off these older juveniles.

DISPERSAL

When the juveniles are evicted from their mother's home range, they will initiate what is called dispersal - the process of leaving their natal range to strike out on their own in search of their own home range. During the eviction phase, juveniles sometimes remain at an edge of their mother's range for a period of one to two months, exhibiting very little movement. Eventually, they will move out of their natal range into new and unknown territory. During dispersal, juvenile bobcats can travel as far as 182 km (113 mi.) over several months before finding a vacant home range in which to settle.

The movement patterns during this time are nomadic and characterized by small, temporary areas of activity which can be occupied for one to two months, before the juvenile moves on. A dispersal pattern can occur in a specific direction, an arc, or a combination therein. In general, it is a wandering type of movement. The time and distance of dispersal depends on the density of bobcats in a population and the rate of adult turnover. The higher the population density and lower the adult death rate, the farther and longer will be dispersals, because of the low probability associated with finding a vacant range nearby.

At the onset of dispersal, males are roughly 60% their adult weight, and females are about 100% their adult weight. Male bobcats become sexually mature (and can therefore reproduce), and reach their adult weight by their second winter of life. On the other hand, female bobcats reach their adult weight and can reproduce before the breeding season of their second year.

TERRITORIAL MARKING

Bobcats maintain and defend their ranges with the use of territorial markers. These markers consist of urine, feces, scrapes, and tree scratches placed along the perimeter and within the interior of the range. They are typically placed in open and conspicuous places such as in the middle of trails and dirt roads.

The objective of this marking behavior is to advertise that the area is occupied by a resident bobcat. If bobcats did not mark their ranges, then other cats would not know a range is occupied. As a result, these other cats would enter and consume the prey of that range. Eventually, the prey could completely disappear as the result of predation by a high number of predators. If this was happening in every range, the bobcats in an area could starve. Thus, marking is a way to conserve food resources. When a bobcat approaches a well marked boundary, it is less likely to wander beyond its range. Like other solitary felids which maintain territories, bobcats also rely on the markings to identify range boundaries in order to avoid combative encounters with a neighboring resident. Wounds acquired as the result of a fight can result in fatal infections.

Urine and fecal markings are usually deposited in conjunction with a scrape. A bobcat makes a scrape by raking its hind paws rearward in order to build a pile of debree consisting of leaves, twigs and dirt. The urine or feces is then deposited onto the top of the pile. In this way, the marker is elevated so that a breeze can carry and spread the smell of the scrape, which is the scent of the marking bobcat. Tree scratches are made at a height of about two feet above the ground on the trunks of trees. Not only do the vertical scratches made by the cat's claws leave a visual marker, but they also leave a scent on the tree which originates from sweat glands in the paws. It is thought that scratching a tree also helps to remove loosened claw sheaths, and not to sharpen claws.

Like other cat species, when a bobcat approaches the scent mark of another, it raises its head with its mouth half open, and upper lip slightly withdrawn. This look gives the cat a grimacing or growl-like appearance. It will stand still, rotate its head, or appear to be staring. This behavior is called "flehmen". They will flehm after smelling any unusual odor. When they do this, they are not expressing any anger suggested by the growl-like look, but in fact activating an organ in the roof of the mouth behind the incisors. This organ is called the vomeronasal organ (VNO) or Jacobson's organ. You can see the openings to the VNO on your domestic cat. They are two small holes in a slightly raised area on the roof.

This organ allows the cat to detect molecules of substances called pheromones. Pheromones are too heavy to be inhaled and detected by typical nasal methods. Pheromones are found in the marking and birth fluids of cats. They provide a way that cats can identify each other more closely or determine if a female is in estrus (ready to mate).

FOOD

Bobcats are strict carnivores and prey upon a wide variety of mammals, reptiles, and birds. In Florida they consume as many as 40 different species of animals. Prey types include cottontail and marsh rabbit, cotton rat, rice rat, wood rat, cotton mouse, golden mouse, Florida mouse, squirrels, moles, voles, shrews, deer, hog, opposum, raccoon, bobwhite, blue jay, meadowlark, robin, thrasher, moorhen, coot, house wren, carolina wren, cardinal, sparrow, and even pygmy rattlesnake.

Because of this wide selection of prey, they can be considered generalists - animals which feed off many different types of other animals. However, in Florida, 68-72% of their diet consists of rabbits and rats. In fact, because of this high preference for these types, they are also considered small mammal specialists in this state.

In Florida, bobcats rarely kill and consume deer. In the north, especially during the winter, when snow restricts the movements of small mammals, bobcats rely more heavily on deer for food. When a bobcat kills a deer in the winter in the north, it can provide food for the bobcat for several days because it is kept fresh by the snow and freezing temperatures. However, in Florida, like the rest of the southeast, temperatures rarely remain below freezing for very long. Thus, deer carcasses cannot stay fresh for more than a day. Because of this, Florida bobcats rely more heavily on smaller animals.

Because these smaller mammals provide less meat than a deer, they have to consume a lot of them. It is estimated that a female bobcat and the three kittens to which she gave birth at the beginning of her second year of life will consume at least 3800 cotton rats, 700 cottontail rabbits, and 3200 cotton mice by the end of her second year. All this prey must be within her home range. Additionally, the adult male bobcat and all the other predators (birds, snakes, foxes, coyotes, etc.) using her range will be consuming many of these prey types as well.

In turn, the prey populations must reproduce fast enough and be of sufficient density to avoid being eliminated by all this predation. The highest predation rates occur on prey species which reproduce rapidly. Conversely, bobcat predation helps regulate prey populations. Bobcat population numbers also fluctuate in accordance with annual fluctuations in prey abundance.

Like most mammalian terrestrial carnivores, bobcats possess teeth which are specialized for the acquisition and consumption for prey. In all, they have 28 teeth. Upper (2) and lower (2) canines are primarily used to kill prey. Conical in shape, upper and lower canines average 2.2 and 1.5 cm for males, and 1.6 and 1.3 cm for females, respectively. They are extremely effective in severing the spinal cord of small prey or delivering severe puncture wounds to a person or an attacking animal. Their roots are about as long as the exposed crown. The supporting sockets in the jaws, especially the upper, consist of strong thick bones in order to accomodate the massive force exerted during a bite.

From 13 to 18 months after birth, the apical foramen of the root of the canines completely closes. The apical foramen is the opening at the end of the root through which the main nerve passes from the jaw to the tooth. When it closes, the main nerve in the root essentially degenerates. Occasionally, a bobcat may break a portion of the tip of the canine when capturing prey. But because the root has closed off, pain is not as intense and there is less chance of the tooth becoming abscessed and rotting away. This can be viewed as an advantage for survival in the wild. Canines are extremely important for killing prey and loss of canines can yield the bobcat less efficient in obtaining food. On the other hand, an abscessed tooth in humans often leads to severe pain and rot if not given dental attention.

Upper (6) and lower (6) incisors are useful for plucking away the skin of prey. Upper (4) and lower (4) premolars and upper (2) and lower (2) molars are used to crunch bone and shred meat. They are generally broad and jagged. These teeth are located closest to the pivot point of the jaw. Thus, the greatest mechanical leverage is imposed on them. If you have a pet domestic cat, you can get an idea of what bobcat teeth look like up close by looking at your cat's teeth. They are similar and perform the same functions.

Bobcats generally consume all the portions of small prey. The exception would include rabbits. Rabbit hide and portions of the digestive tract are typically discarded. Of importance in consumption is the acquisition of vitamin A. Cats appear to not be able to convert pro vitamin beta carotene into fat soluble vitamin A (retinol). Thus, all vitamin A must be acquired from the liver, lungs, kidneys, or adrenals of prey. A lack of vitamin A may lead to egg implantation failure in females. This would reduce conception rates. It may be the reason that conception rates are relatively low in areas where bobcat densities are high, thus leading to over-predation and a shortage of prey-derived vitamin A.

Cats also require a high protein diet and because of mechanisms associated with nitrogen processes in feline physiology, cats cannot utilize vegetable sources of protein, even when prey sources are low.

MOVEMENTS AND ACTIVITY

Bobcats are extremely active. They spend about 75-85% of their time moving. When they do rest, they only spend an average of two to three hours at any one rest site. They can move as fast as 10 km (6.2 mi.) in 24 hours.

The bulk of the longer movements occur around dawn and dusk. During midday and around midnight, they move the least. This type of activity is what is called crespucular or bimodal. Movements may be classified as foraging or long distance. Foraging movements take place in habitats which are dense in prey. They are highly localized in a relatively small area. On the other hand, long distance movements probably serve to get the bobcat from one end of its range to the other in order to mark it or locate other areas possessing dense prey.

A typical movement pattern in a 24 hour period can consist of the following: resting in a secluded and comfortable day bed from 11AM to 3PM; localized foraging from 3PM to 5PM; long distance movement from 5PM to 9PM; resting and localized foraging from 9PM to 11PM; long distance movement from 11PM to 1AM; rest from 1AM to 3AM; long distance movement and foraging from 3AM to 9AM; rest from 9AM to 11AM.

Because of all this movement, Florida bobcats expend a lot of energy. It is estimated that males and females expend a minimum of 1121 and 738 kilocalories of energy over a 24 hour period, respectively. This amount of energy must be derived from the prey sources found within a bobcat's home range.

Movement rate versus time of day. Notice the peaks in rate at sunrise and sunset. We call this crespucular behavior.

HABITATS

The kinds of habitats which bobcats prefer is strongly dependent on prey availability. However, protection cover from severe weather, suitability and availability of cover for rest and den sites, sufficient cover for foraging and evasion from danger, and freedom from disturbance are additionally important. Thus, habitats which promote prey densities and cover are ideal for bobcats.

However, small mammals, which the bobcat prefers, occur in greatest numbers in habitats which possess a lot of young vegetative growth, sparsely located trees and shrubs, and ample grasses, forbs, and herbs. These kinds of habitats are called early successional communities. Unfortunately, these habitats can be deficient in cover. Conversely, older habitats (late successional areas) or those which are dense in trees and shrubs, are abundant with cover, but less abundant in small mammals, because of the lack of herbaceous growth.

Thus, a landscape which has a spatial mix of young and old habitats would be ideal for bobcats. Such a mix provides high densities of preferred prey sources (early successional areas) near the cover bobcats like (late successional areas). Typically preferred habitats include mixed hardwood swamps, pine flatwoods, upland hardwood forests, hardwood hammocks, old fields, and farmlands interspersed with heavily wooded forests.

As far as prey goes, pine flatwoods and early successional areas contain cotton rats and cottontail rabbits, forest swamps contain cotton and golden mice, and agricultural areas contain rabbits and rats. Edges of forest swamps and flatwoods appear to be particularly favored. These edges are called ecotones. Species from the habitats on both sides of the edge coexist at the edge, and thereby provide bobcats with a higher abundance and diversity of prey in a relatively small area as compared with the interior of a single habitat.

Dens must adequately provide security and comfort for a bobcat. Such includes security from outside intrusion from other animals or people. Dens must also help the bobcat cope with extreme temperatures. During the hotter summer months, shade is important. During the coldest nights of winter, a den must possess sufficient vegetation to help thermally insulate a bobcat from the cold. Dens can be dense vegetation thickets, brush piles, or hollow dead trees. Where they exist, saw palmetto thickets are favored for denning.

Females tend to use higher quality habitats more than males, because they have the need to obtain a lot of prey from smaller areas when rearing kittens. Such helps to offset the high energetic demands of providing for dependent kittens. However, during the first few months of life, kittens are vulnerable to predation by other animals. Thus, natal dens need to be especially well concealed deep enough into a forest. It is also because of these reasons that natal dens can frequently be found in thick vegetation which is relatively near a prey dense habitat. Such makes life easier for the mother.

MORTALITY

Bobcats die as the result of many causes. The leading cause of death may be hunter-induced. However, causes of death can be due to predation by other animals, collision with automobiles, starvation, and disease. Hunter-induced mortality (hunting and trapping) can account for as high as 67% of deaths. This cause of mortality peaks during winter months in areas where bobcat hunting is legal.

A number of wild animals occasionally prey upon bobcats. Panthers infrequently kill bobcats and coyotes have been known to prey upon kittens. Collision with automobiles appears to be increasing as a result of urban encroachment into bobcat habitat. High speed roads which are constructed to link communities between natural areas bisect home ranges. As a result, bobcats in remote areas which have never encountered vehicles and roads, and unwarily wander onto a road at the wrong time, are often hit by a vehicle.

Starvation probably peaks in the winter and early spring when rabbit and rodent populations are the lowest. Juveniles are particularly vulnerable during this period since it coincides with weaning. Diseases may be predisposing factors contributing to bobcat mortality, but are generally not a major cause of death. Exceptions would include epidemic proportion outbreaks. Feline panleukopenia has been implicated in the near decimation of a population in south-central Florida. Ironically, this disease can be contracted from domestic cats. Bobcats which encounter feral or free-ranging house cats that venture outside an urban area or live in a rural setting are at the highest risk. Such may be a common occurrence in severely fragmented populations. Rabies might be another decimator of bobcat populations.

Survival rates generally increase with age in young bobcats, which reflects greater foraging efficiency with age and experience. Mortality can have consequences that reach beyond the death of the individual. When a mother is killed, orphaned kittens which are less than five months old have little chances for survival. The younger they are, the easier they can succomb to starvation or predation.

THE ROLE OF FIRE

Fire plays an important ecological role for bobcats in Florida. When a fire spreads through a habitat, heavy brush, old trees, and ground litter are consumed. This clearing mechanism opens up the forest canopy so that direct sunlight can strike the ground. Such stimulates the growth of herbaceous and shrubby plants which are important sources of food and cover for many small mammals. In time, as the herbaceous mass and young shrubs increase, the burned out forest will become repopulated with these small mammals to levels which exceed those found in old, dense, and thick forests which experience no fire.

With the increase in small mammal numbers, bobcats have a greater number and variety of prey upon which to feed. In response, bobcat reproduction and numbers can increase. Because of the higher densities of prey, bobcat home ranges usually shrink - they do not need to defend large areas in order to conserve prey resources.

POPULATION VIABILITY AND ECOLOGICAL STABILITY

Because of the territorial nature exhibited by bobcats, land is partitioned in much the same way as humans occupy property and houses. This territorial feature coupled with the solitary occupation of ranges and the large sizes of those ranges dictates that a lot of wild land must be left intact in order to meet the needs of a population.

It is estimated that a viable population of bobcats needs to have 200 individuals occupying 159,000 acres of forested land with sufficient prey resources in order to insure long term persistence free of any degradable biomedical effects associated with inbreeding. Natural lands on the order of 100,000 in size are becoming increasingly scarce in Florida. As natural landscapes in Florida continue to be rapidly lost or fragmented by urbanization, bobcat populations will gradually shrink in numbers or completely disappear.

As a wide-ranging predator, bobcats are important components of natural systems. Loss of this predatorial component can have pronounced effects on ecological stability. Florida has already experienced a loss in numbers of major wide-ranging large carnivores such as the panther. The only known breeding population of panthers exists in south Florida.

Because of the panther's absence from the rest of Florida, prey populations such as raccoons have increased. This mesopredator release, in turn, has led to an over-consumption of their food supplies, such as sea-turtle eggs along Atlantic beaches. Such may be a contributing factor to sea turtle endangerment.

Thus, central to the dynamics of species extinction is the loss of habitats. If habitats continue to be fragmented or lost in Florida, the bobcat may end up on the endangered species list one day. But before that happens, many local populations in Florida will probably disappear. Moreover, its absence as a predator of the forest may have degradable effects on other species.

WHAT CAN YOU DO?

If this site has stimulated your thinking, then use it to take positive action aimed at habitat preservation. Make your voice heard in government to stop development into undisturbed tracts of land. Pass this information onto your friends and family. Be an educator and defender of wildlife. Remember, one voice can make a difference, but no voice is never heard! The more knowledge that many people gain, the greater will be their power in effecting land use decisions made by our elected officials.

	A bobcat foraging for food in an early successional area.
	A hardwood swamp. Tree species include gum, maple, cypress, and slash pine. The interiors of hardwood swamps possess dry areas suitable for bobcat denning through drier seasons.
	Pine flatwoods. The primary tree species is slash pine. Fetterbush, wax-myrtle, saw palmetto and other shrubs occupy the underbrush layer. The interiors of unburned mature flatwoods are dark and dense with shade-tolerant shrubs. Their cover gives the bobcat a great sense of security.
	An open grassy edge between a flatwoods (left side of photo) and a hardwood swamp (right side of photo). Prey species from both the flatwoods and swamp occupy this edge. As a result, bobcat prey abundance and diversity are the greatest at the edge in comparison to the interiors of the flatwoods and swamp. Notice how the sunlight fosters abundant grassy growth.
	A shrubby swamp edge. Bobcats favor such shrubby edges for dense cover and well secluded den sites.
	An upland hardwood forest. Species of oaks and other hardwoods occupy these dry habitats. Saw palmettos are common. In certain parts of Florida hardwood habitats take on a lush tropical-like appearance.
	An agricultural old field favored by bobcats for its cottontail rabbits and rats.