alyzed certain aspects of the component level structure and pattern in a micropar- asite community using quantified density data. Our objectives were to examine.
Journal
EFFECTS
OF HOST
AND
SPATIAL
COMMUNITY
IN MOURNING
Ralph
Jr.,
2
0. Godfrey,
Department
of Range
Department
of Pathology,
Author
to whom
Danny
and
reprint
DOVES
B. Pence,23
Wildlife
Management,
Texas Tech University requests
FACTORS
should
FROM
and
Alan
Texas
Tech
Health
Sciences
of Wildlife
Diseases, © Wildlife
26(4), 1990, pp. 435-441 Disease Association 1990
ON A HAEMOPROTEID WESTERN
TEXAS
M. Fedynich University,
Lubbock,
Center,
Texas
Lubbock,
Texas
79409, USA 79430, USA
be addressed
ABSTRACT: Two species of hematozoa, Haemoproteus columbae and H. sacharovi, were observed on thin blood smears from populations of mourning doves (Zenaida macroura) in the Rolling Plains (RP, a semiarid dryland farming and grazing area) and Southern High Plains (SHP, an intensively cultivated and irrigated agricultural region with playa lakes) of western Texas (USA). Prevalences of H. columbae and H. sacharovi were 91 and 18% in doves from the RP (n = 44 doves examined) and 81 and 36% in those from the SHP (n = 84), respectively. Although the prevalences of these species were not significantly different between the RP and SHP, the prevalence of H. sacharovi was significantly greater in juvenile versus adult doves from both localities. Mixed infections of both haemoproteid species occurred in 11 and 24% of the doves from the RP and SHP, respectively. The frequency distributions of the relative density values (numbers of parasites/2,000 erythrocytes counted) of H. columbae and H. sacharovi were overdispersed in hosts from both localities. Relative densities of H. columbae were significantly higher in mourning doves from the RP versus the SHP; likewise those of H. sacharovi were significantly greater in juvenile versus adult doves and between localities. Observed differences in prevalence and relative density of the two species in the haemoproteid community across spatial and host variables may reflect differences in vector transmission and in the physiological and immunological status of the
host.
This
study
emphasizes
the
importance
of
using
adequately
quantified
density
data
versus
only prevalence data when examining microparasite communities at the component community level. Key words: Hematozoa, Haemoproteus columbae, Haemoproteus sacharovi, mourning dove, Zenaida macroura, component level community ecology, host sex effects, host age effects, locality effects,
prevalence,
relative
density,
field
study.
microparasites, INTRODUCTION
Most the
contemporary
component
roparasite sembleges hosts
(helminths occupying are
based
Alternatively,
utilizing
studies level
on
at mac-
and arthropods) niches in vertebrate
on
relative
because
ciated with communities the parasitic prevalence dicated host,
ecology
community
density
of difficulties
as-
data.
on the ponent
asso-
macroparasitic
quantification, most studies on of microparasites, including protozoa, have been based on data. However, even studies
only trends temporal
data
on
prevalence
of changing and spatial
have
such
as the
avian
hemato-
zoa, have been based on only frequency data or, at best, frequency data and subjectively ranked density data. Therefore, these analyses lack the robustness of studies community community
ecology at the level of free-living species
where
comor
relative
dis-
tributions a habitat
in numbers of individuals can be considered. Utilizing
across the
methods
of Godfrey
et al.
(1987),
we
an-
alyzed certain aspects of the component level structure and pattern in a microparasite community using quantified density data. Our objectives were to examine the
in-
patterns across variables in
communities of such groups as avian haemosporidians (see Greiner, 1970, 1975). Although there have been attempts to quantify microparasites within host individuals and to examine these data across host and temporal variables, the methods
main and interactive effects of selected host and spatial variables on the hematozoan community in an avian host. We examined the effects of (1) host age, (2) host sex and (3) locality on the prevalence and density
were
moproteus
in the
mourning
macroura)
from
western
Thus,
often
subjective
previous
studies
(Godfrey on
et a!., the
ecology
of
1987). of 435
a community
of
two
species dove Texas
of
Hae-
(Zenaida (USA).
436
JOURNAL
OF WLDLIFE
MATERIALS Study
DISEASES,
AND
VOL.
26, NO. 4, October
METHODS
area
Doves were collected from localities in Castro County (34#{176}25’N, 102#{176}02’W) and Foard County (33#{176}71’N, 99#{176}38’W) in western Texas. These counties are in the Southern High Plains (SHP) and Rolling Plains (RP) vegetation zones, respectively. The SHP was originally a short grass prairie which is now used largely for intensive agricultural cultivation of row crops such as corn, grain sorghum and cotton; there are numerous (>0.5 km2) shallow intermittently flooded basins called playas that provide most of the habitat for wildlife in the region (Guthery, 1981; Simpson et al., 1981). Bruns (1974) and Bolen and Guthery (1982) further discuss the characteristics of Castro County. Major land use features of the RP include dryland grain production and rangeland for cattle. Vegetation in the RP consists of mixed grass species interspersed by juniper (Juniperus sp.) breaks and mesquite (Prosopis glandulosa) flats. The area is described in detail by Koos and Dixon (1964). The greater availability of wildlife habitat in the RP suggests a more homogeneous distribution of doves than occurs in the SHP where they are concentrated near the playas. Additionally, surveys by the Texas Department of Parks and Wildlife (Austin, Texas 78744, USA) indicate that breeding populations of mourning doves were higher in the RP than the SHP (George, 1988).
Data
collection
Mourning doves (n = 128) were collected by shooting from 1 to 8 September 1985. We regarded these birds as residents because (1) band recovery analyses of mourning doves harvested in
the
northern
hunting
zone
of
Texas
showed
that the majority of all birds shot originated from the same zone (Dunks, 1977) and (2) all doves were collected prior to any major cold frontal activity, thus assuring that mainly resident and not northern migrants were collected. Birds were aged by plumage and gonad characteristics (Cannell, 1984; Bivings and Silvy, 1980) and sexed by gonad examination. Two thin blood smears from each dove were made from heart blood immediately (