COYOTE BYTES



April 12, 2006

 


Coyote Carcasses Yield Info about Coyote Diet and Health

by Charles Brown, Wildlife Biologist, Rhode Island Division of Fish and Wildlife


Photo courtesy of Bev Wigney

The DEM’s Division of Fish and Wildlife has been examining the stomach contents of coyotes that have been collected as part of a surveillance effort for canine heartworm (Dirofilaria immitis) and other diseases and parasites. Since 1999, we have examined 61 coyotes from twenty Rhode Island towns (see Table 1). Coyote carcasses are collected opportunistically. Some have been killed by automobiles; others have been voluntarily submitted by hunters. Examination of these animals has provided useful information about coyote life history and dietary habits.

 The amount of information collected often depends on the condition of the specimens.  Some were too badly damaged or decomposed to yield much useful information.  Wherever possible, however, we performed necropsies in which we noted physical characteristics such as the animal’s weight, age, reproductive history, stomach contents, and parasite load.  


 Stomach Contents

The examination of stomach contents provides some insight into the dietary habits of coyotes. Although our sample size is relatively small, it still provides information into the type of food resources being utilized in our area. It has long been recognized that coyotes are opportunistic predators and scavengers, utilizing a wide variety of food resources limited only by their availability.  The availability of different food items varies according to region and time of year.  Coyotes will utilize those food resources that are readily available and easiest to obtain.

 Most of our samples (42) were from winter months (December to April).  There are few samples from other seasons making comparisons of diets between seasons difficult.  Interestingly, 42% of all coyotes DEM examined had empty stomachs at the time of their death.

 Table 2 below shows relative abundance of different foods in the coyote stomachs.  Wild fruits were an important component in coyote diet as evidenced by the presence of crabapples, wild grapes and other berries found in the stomachs of the coyotes we examined (21% overall).

 In addition, DEM also found that 11% of animals examined had recently eaten human-related food items such as pet foods and a variety of garbage (cooked chicken bones, macaroni, plastic bags).  Whether people intentionally or unintentionally make food available, coyotes will readily incorporate it in their diets. Reducing or eliminating the availability of such food resources will prevent many of the interactions that occur between people and coyotes.  

Almost 15% of the coyote stomachs contained the remains of deer.  It is impossible to say how the deer the coyotes consumed were obtained.  Under the right circumstances, coyotes are capable of killing deer, but they certainly take advantage of deer that were killed by other means such as auto strikes, disease, or deer that are unable to be retrieved by hunters.  Smaller mammals, many of which were identified to species, were found in 26% of the stomachs.  Examples were white-footed mice, meadow voles, gray squirrels, and rabbits.  

Heartworm

 During the same period we conducted surveillance for canine heartworm (Dirofilaria immitis) in coyote carcasses we examined.  Heartworm is a nematode that also afflicts domestic dogs and foxes. In severe infestations the nematodes clog the inside of the heart; interfering with circulation that may lead to the early death of adult coyotes. 

 Sixteen (26%) of the 61 coyotes examined showed evidence of heartworm infestation.  We have found that most adult coyotes (animals more than 2 years old) examined had heartworm.  Of the 45 animals which did not show evidence of heartworm only two were adults. 

 Since their first appearance in Rhode Island in the late 1960’s coyotes have become ubiquitous throughout most of the state. Their presence in the state has generated quite a bit of interest, much of it, unfortunately negative.  Often, negative responses to wildlife come from a lack of knowledge about them. The study is ongoing and the DEM will continue to collect and examine coyotes whenever possible.  Over time, as the sample size increases, we will know much more about Rhode Island coyotes. For additional information visit the DEM website at www.dem.ri.gov/topics/wildlife.

Table 1.  Coyotes examined from Rhode Island towns

Town

Number of coyotes

Barrington

2

Charlestown

2

Coventry

1

Cranston

1

East Greenwich

4

East Providence

2

Exeter

5

Hopkinton

8

Jamestown

2

Johnston

1

Little Compton

2

Narragansett

1

North Kingstown

2

Portsmouth

2

Providence

1

Richmond

1

Smithfield

1

South Kingstown

8

Warwick

5

 Westerly

7

Unknown

3

You can contact Charlie at the RI Division of Fish and Wildlife, 401-789-0281,charles.brown@dem.ri.gov

Table 2. Rhode Island coyote stomach content analysis

Number of occurrences

Item

All Seasons (N=61)

Winter (N=42)

Spring (N=3)

Summer (N=3)

Fall (N=13)

deer

9

5

2

1

1

other mammal*

16

11

0

2

4

fruit/grain

13

6

0

2

5

bird

6

4

1

1

0

garbage, dog food

7

3

1

1

2

none

26

20

1

0

5

 

 

 

 

 

 

Percent of occurrences

Item

All Seasons (N=61)

Winter (N=42)

Spring (N=3)

Summer (N=3)

Fall (N=13)

deer

14.8%

11.9%

66.6%

33.3%

7.6%

 *includes: gray squirrel, white-footed mouse, meadow vole, rabbit, raccoon, and unidentified

Charlie helps collar a coyote at Chase Farm, Portsmouth, on a very cold January day.

Photo by Numi Mitchell

Charles Brown and the Staff at Rhode Island Division of Fish and Wildlife, DEM,  are dedicated to gathering information on wildlife populations and developing strategies for their sustained management in Rhode Island.  They also develop regulations and DEM officers make sure people abide by them.  They have many informative documents available about coexisting with wildlife.  Charlie is particularly  interested in native mammals (from star-nosed moles, to beavers, to coyotes).  He is never to busy to investigate wildlife issues or save a valuable specimen for study.  He frequently visits schools, libraries, or gives lectures on human/wildlife interactions and safe practices around wildlife.  He has been a thoughtful and helpful advisor to the Narragansett Bay Coyote Study from the outset.