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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