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
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.
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
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
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
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
coyotes. For additional information visit the DEM
website at www.dem.ri.gov/topics/wildlife.