no rabid raccoons reported in Maryland, but in 1983. Maryland reported the largest .... Animal. Shelter. (MAS;. Baltimore. City. Health. Department,. Bureau.
Journal
of Wildlife
Diseases,
26(2),
© Wildlife
LAND
USE ASSOCIATIONS
INDICES
OF URBAN
Jill A. Anthony,16 Lloyd Ross,4 and
AND
CHANGES
RACCOONS
James E. Childs,2 Jack K. Grigor5
1990, pp. 170-179 Association 1990
IN POPULATION
DURING
Gregory
Disease
A RABIES
E. Glass,2
George
W.
EPIZOOTIC Korch,3
1 Department of Environmental Sciences, The University of Virginia, Clark Hall, Charlottesville, Virginia 22904, USA 2 Department of Immunology and Infectious Diseases, The Johns Hopkins University, 615 North Wolfe Street, Baltimore, Maryland 21205, USA US Army Environmental Hygiene Agency, Aberdeen Proving Ground, Maryland 21010, USA 4The Baltimore City Health Department, Bureau of Animal Control, Baltimore, Maryland 21230, USA Division of Veterinary Medicine, Maryland Department of Health and Mental Hygiene, Baltimore, Maryland 21201, USA 6 address: School of Fisheries and Ocean Sciences, The University of Alaska-Fairbanks, Fairbanks, Alaska 99775, USA
population December city streets
Land use associations and changes in population indices were assessed for an urban of raccoons (Proc yon lotor) in Baltimore, Maryland (USA), from January 1984 to 1987. Records were examined for 1,458 raccoons trapped alive and removed dead from during, and after, the peak of a rabies epizootic. The distribution of raccoons was
associated
with
ABSTRACT:
the
of
city.
through
spread
the
study showing kills)
The
Key
not
Raccoon, use
in
the
yon
Proc
association,
with
animal
potential
for
number
lotor,
of
urban
zoonotic
exposure has increased development.
eases
urban adapted
to
communities,
living and
lotor) is an al., 1970).
important
vide
food,
port tion
ample
human
to wildlife with Many in the
and
population,
exceptionally densities (Bigler
water
shelter
high raccoon et al., 1973;
and Gottschang, 1977; Hoff Rosatte, 1985). In 1977, a wildlife rabies
released
to supplement
subsequently, ginia, the and
western of
perimeter raccoon
decrease city
in
and
in
the
private
rabies
urban
raccoon
control,
appears
Baltimore.
rabies,
rabies
epizootic,
population
pro-
Prior
to 1981,
there
were
Maryland, the largest
=
1979; be-
detected the first rabid raccoon within the city limits. As of December 1987, 95 rabid raccoons had been reported within mu-
of the linked to enzootic of rabies
populations
Pennsylvania.
in VirMaryland
number of rabid raccoons in the country (n 735; Jenkins and Winkler, 1987; Centers for Disease Control, 1988). In March of 1985, the City Department of Health in Baltimore, Maryland (USA)
populaHoff mann
epizootic
cases were reported District of Columbia,
no rabid raccoons reported in but in 1983 Maryland reported
et
to sup-
mann,
gan in the mid-Atlantic region United States. This outbreak was raccoons translocated from the southeastern United States focus and
dissubhave
(Kappus
settings and
epizootic
raccoons hunted for sport (Nettles et al., 1979; Smith et al., 1984). The first rabid raccoon in the epizootic was detected in West Virginia (Smith et al., 1984), and
human (Proc yon
raccoon example
a specific increased
raccoons
domestic
around
Suburban-urban
an
disease.
and their urban and mammals
and
and
northern
1987,
identification
the
INTRODUCTION
The
May
suggesting
in conjunction
a decline
in
in the
concurrently,
epizootic, to
land
1987.
decrease
the
along
ending
of 95 rabid raccoons. Within of trapped raccoons remained stable from 1984 to 1986, before The number of raccoons removed as vehicle mortalities (roadbut declined in the last 2 yr of study. Numbers of other road-
1984-1985
rabies
words:
dynamics,
in
primarily
an
resulting
numbers
from
contributed
1985
ultimately
annual decline
did
species
areas
March
Baltimore,
little
population. have
residential in
interval, a marked
varied
killed to
single-unit
Beginning
nicipal Baltimore of Health and Raccoons
of 170
in
(Maryland Mental Hygiene, Baltimore
Department 1987).
have
been
re-
ANTHONY ET AL-A
duced
in number
fects
of the
public and this study sociations of abundance
due
to the
rabies
epizootic
private was to
control. document
of
urban before,
rabies poral rabies
epizootic. and spatial epizootic.
useful
in
combined and The
raccoons during
ef-
increased
purpose land use
of as-
and and
patterns after the
also describe pattern of the This information
the temraccoon may be
We
predicting
the
geographic
spread
of rabies in comparable environments and in anticipating population changes associated with disease and control. Data on the
distribution
urban
raccoons
control vaccines
and
relative
may
also
abundance aid
future
of rabies
programs aimed at delivering to wildlife (Winkler and
1976; Rupprecht al., 1989).
et al.,
1986;
oral Baer,
Hadidian
et
and
and mapping
technique
The timore,
study area encompassed municipal BalMaryland (39#{176}22’to 39#{176}12’N, 76#{176}43’to 76#{176}33’W) which spans approximately 227-km2; 2 12-km2 is land intermingled with flowing water, lakes or reservoirs, and 15-km2 is harbor water (Baltimore City Land Use Map, 1978, Maryland State
Department
Maryland
of
21202,
USA).
Planning, A map
Baltimore, of Baltimore
was
grid squares. Raccoon home ranges in suburban locations have been reported as small as 5 ha, but are typically in the range of 40 ha, or more, in rural locations (Kaufmann, 1982). Each grid square was classified according to major land use and the presence of various types of water (see Childs and Ross, 1986). Land use categories were multi-unit residential, single-unit residential, open land, into 400
marked
x 400
m
(16
ha)
commercial-industrial-institutional, Multi-unit
residential
areas
and were
water.
characterized
by connected row house architecture with high human population density; single-unit residential consisted of unattached dwellings, most frequently located in a suburban setting. Open land included parks and cemeteries. Commercial-industrial-institutional areas were typified by low human population densities and low number of residential
Animal
The mals from
units.
data
collection
raccoon trapped Baltimore
disposition
sample alive
was comprised of anior removed dead or injured city streets by the Municipal
of each
The
MAS
trap
(Tomahawk
hawk, upon tured disposal
The
also
IN URBAN
RACCOONS
and
171
of available from study
examined
report
Trap
live
Company,
a replacement
the
maintained.
Tomahawk
Toma-
54487, USA) to homeowners, for trapping of raccoons. Capwere removed by the MAS for
ranged
During
were
a single
Live
number
period
animal
supplied
Wisconsin request, animals
were METHODS
area
EPIZOO11C
Animal Shelter (MAS; Baltimore City Health Department, Bureau of Animal Control, Baltimore, Maryland 21230, USA) from January 1984 to December 1987. The MAS responded to calls from residents of Baltimore City reporting dead or injured animals on city streets. From two to four vehicles, each operated by one or two city wardens, were available to respond to daily requests for dead or injured animal removal or other assistance. The city attended to all calls reporting wild or domestic animals with equal effort. Detailed records of the location, health
a
Study
RABIES
and
date,
a
trap
traps
35
in 1984
period
each
provided.
the
to 110
MAS
raccoon
removal
was
during daily
records
was
location,
study
in 1987.
assigned
and
a
con-
dition upon removal (trapped alive or removed dead). Most raccoons, other than those trapped, were removed dead or injured from city streets, probably as the result of accidents with motor vehicles. Daily records for years prior to 1984 were not examined as these were unavailable for study.
To control for changes in raccoon removal rates potentially caused by changes in MAS collection patterns, daily records for cats and dogs killed and removed from streets were examined over the same period. A previous study on roadkilled cats indicated that MAS records provided a reliable and unbiased index of animal removals from different land use types in Baltimore, with approximately 50% of cats killed by vehicles (road-kills) being removed from city streets by the MAS (Childs and Ross, 1986). Locations of raccoons collected alive or removed dead from January 1984 through June 1987 (>93% of the total sample) were determined on the city map of Baltimore with a crisscross directory (The Baltimore City Criss-Cross Directory, 1986, Stewart Directories, Baltimore, Maryland in a 16-ha was
used
21204,
USA).
grid
square
to determine
Each and
location
the
relative
was
resulting raccoon
fixed
map density
and habitat distribution. Raccoons tested for rabies were plotted in an identical manner and centers of activity for the rabies epizootic were determined for 1985-1987, after the home range method of Hayne (1949). These values represent the geographic centers of all positions of rabid raccoons for each year, as computed by averaging x (west to east) and y (north to south) grid coordinates of individual locations.
172
JOURNAL
OF WILDLIFE
DISEASES,
VOL. 26, NO. 2, APRIL
1990
(b)
(a)
Water FIGURE Mary
land.
Rabies
1.
a.
(1
Grid
use
map
Square
of 16
=
Baltimore,
Maryland.
movals 1984;
rabies antibody were conducted
tests (FRA; Johnon fresh or frozen of raccoons by the Maryland
impressions
Department
of Health
and
Mental
Hygiene.
Instruments,
Baltimore,
Maryland
USA)
for detection
of antigen.
After
mation jority either signs,
of rabies of raccoons suspected or involved or domestic
mans
to the Health
The
Statistical
(yearly
ANOVA
(LSD)
the
by
the
temporal
MAS.
Bonferroni proportion
of
Difference
analysis
confidence of raccoon
land
use
1974).
This
type
(Byers
method
et al.,
computes
intervals for comparproportion of removals area represented by these analyses, an upper value corresponding to a a/2k (Z,,126) was selected 4 classifications of land Z0 = 2.495.
Numbers
The tween
of raccoons
MAS January
these, (21%) this
During
were
removed 1984
1,150 were
and
1,458 raccoons December
(79%)
interval, for rabies
be1987.
were
trapped and as road-kills.
live
raccoons were and 95 of these
removed 438
testing
positive.
(SAS
distributions table
each et al.,
submitted
examined
comparisons
Geographical
contingency
of 95% true
were
Significant
multiple
of Baltimore,
RESULTS
Of
distribution
monthly)
Least
for
Inc., 1985).
analyzed
computation tervals for
and
from Neu
“family” of confidence ison with an expected based on the proportional each land use type. In standard normal table probability tail area of for a = 0.05 and k = use. In this case Z,,25
308
and
criteria
Institute, were
by
in the
Fluctuations
map
confir-
methods
raccoons
by
21214,
the
in Baltimore in 1985, the matested by the laboratory were of being rabid, based on clinical in potential exposures of huanimals. Most were submitted Department
b. Water
16 ha).
=
a
tests used fluorescein isothyocyanate conjugated Anti-Rabies Monoclonal Globulin (Centocor, Malvern, Pennsylvania 19355, USA) for staining, and a Zeiss epi-fluorescent microscope (Baltimore
Square
(1 Grid
ha).
testing
Fluorescent son, 1969) brain
Land
Land
use associations
and
inre-
The squares
city
was
classified
divided primarily
into as
1,327
grid
land
(Fig.
ANTHONY
TABLE
1.
Land use occurrence and simultaneous by trapping or as road-kills, January
Maryland,
ET AL-A
EPIZOOTIC
intervals for
confidence
1984
RABIES
to June
IN URBAN
raccoons
RACCOONS
removed
from
173
Baltimore,
1987. Raccoons
Trapped
Land
use
Expected proportion’ of removals (P,,)
(P)
Multi-unit
(1)
land
Cu2
0.254
0.168
0.140
0.221
0.587
0.550
(3)
0.187
0.139
0.113
0.338
0.106
0.083
(4)
Proportions
of removals
use. P represents
expected
proportion
is accepted
or
Bonferroni
(2)
Single-unit Open
Actual proportionb of removals (P,)
if raccoons
of removals
each
la). An additional water, 30 contained
land
0.05
level
use
category
93 squares were harbor a lake or reservoir, and
were
significant
associations dead
as land, ib).
differences of
(x23
P
29.87,
=
in the
raccoons
cations, but more equitably use
types.
land mals,
the
The
road-killed distributed
