Bird Feeders and the Spatial Distribution of Ticks on a Residential
Lawn in Worcester County, Massachusetts
John P. Kowalczyk1,* and Tamara L. Smith2
Abstract - In order to assess the effect of bird feeders on the distribution of ticks on a residential
lawn, ticks collected beneath bird feeders were compared to similar control areas on a
residential property in Worcester County, MA. Host-seeking ticks were sampled from August 8,
2005 to July 25, 2007 by dragging with white flannel cloth. All ticks were counted and removed
from the cloth. Sampling was conducted 38 times. A total of 12 ticks (larvae and nymphs) was
collected. Significantly more ticks were collected from under the bird feeders (n = 10) than the
control areas (n = 2).
The role of ticks as vectors of disease-causing pathogens is of significance to
both veterinary and human medicine. Of particular concern in the northeastern
United States is Ixodes scapularis Say (Blacklegged Tick, more commonly referred
to as Deer Tick). The Blacklegged Tick is a vector for human granulocytic ehrlichiosis,
babesiosis, and more commonly Lyme disease. Lyme disease is caused by
the spirochete Borrelia burgdorferi Johnson, Schmid, Hyde, Steigerwalt and Brenner
(Burgdorfer et al. 1982), which the Blacklegged Tick may acquire during a blood
meal from an infected host. Larvae and nymphs often feed on Peromyscus leucopus
Rafinesque (White-footed Mouse), an important reservoir host of B. burgdorferi.
Understanding the mechanisms that foster increasing human encounters with ticks
has been an important part of coping with the problem.
It is likely that many cases of Lyme disease result from encounters with ticks on
the patient’s own property (Falco and Fish 1988) and that landscape features present
on residential properties (ornamental vegetation, stone walls, woods, ecotone, and
lawn) may influence the presence and distribution of ticks on those properties (Frank
et al. 1998). It has been speculated that ground-feeding birds and rodents attracted
to the seed falling beneath bird feeders may be the source of infected ticks. Leaving
feed for birds (Smith et al. 2001) and the presence of a bird feeder (Orloski et al.
1998) were identified as risk factors in case-control studies of the incidence of Lyme
disease. Townsend et al. (2003) addressed this risk factor using statistical analysis of
survey data as well as measurements of tick densities on residential properties and
found no correlation between the presence of a bird feeder and the incidence of Lyme
disease or the density of ticks.
Our study was designed to investigate the relationship between bird feeders and
tick distribution on a finer scale. If ticks detach or are dislodged from ground-feeding
passerines and/or rodents foraging on the seed beneath bird feeders, there may be
more ticks within 1 m of the feeders than areas of comparable size elsewhere on the
lawn. We compared the number of ticks sampled directly beneath bird feeders with
those from control areas ≈4 m distant.
Study site. The site was a 0.5-ha residential property located in Mendon, Worcester
County, MA. The CDC has classified this county as a high-risk area for Lyme disease
(CDC 2006). The property was mostly lawn with fruit trees, shade trees, ornamental
shrubs and flowers, stone walls, wood piles, and a small forest island (about 150 m2)
as well as a vegetable garden (≈50 m2) and a shed. The property adjoined 0.7-ha of
old field characterized by Acer spp. (maples), Fraxinus americana L. (White Ash),
Rhus spp. (sumacs), Populus deltoides Bartr (Quaking Aspen), Rhamnus cathartica
L. (Common Buckthorn), and Ilex verticillata L. Gray (Common Winterberry Holly).
It supported many tick host species: Microtus spp. (voles), Tamias striatus L. (East-
Notes of the Northeastern Nat u ral ist, Issue 15/3, 2008
469
470 Northeastern Naturalist Notes Vol. 15, No. 3
ern Chipmunk), Marmota monax L. (Woodchuck), Sylvilagus transitionalis Bangs
(New England Cottontail Rabbit), Sciurus carolinensis Gmelin (Gray Squirrel), Tamiasciurus
hudsonicus Erxleben (Red Squirrel), Mephitis mephitis Shreber (Skunk),
and White-footed Mouse. Vulpes vulpes L. (Red Fox), Canis latrans Say (Coyote),
and Odocoileus virginianus Zimmermann (White-tailed Deer) have been seen on the
property. The residential lot and adjacent old field were surrounded by paved road
(north and west), residential property (south), and commercial property (east). The
lawn was mowed approximately weekly. No insect control products were applied to
the lawn. Among the various bird species observed foraging on the study site were
Cardinalis cardinalis L. (Northern Cardinal), Melospiza melodia Wilson (Song Sparrow),
and Turdus migratorius L. (American Robin), birds reported to be infested with
sub-adult Blacklegged Ticks (Hyland et al. 2000, Scharf 2004).
Materials and methods. Nine birdfeeders were maintained throughout the property.
A control area was designated at 6 m from each feeder. The controls were chosen
to be in the same proximity to landscape features (e.g., ecotone, woodpiles, or stone
walls) as the feeder. Each station was at least 5 m from the edge of the lawn. Seven of
the feeders were suspended from 2.18-m Shepherd’s hook hangers: feeders 1 through
6 were cylindrical tube feeders (6.5 cm in diameter x 32 cm long) with six feeding
perches from which birds of various sizes could feed, feeder 7 was a larger cylindrical
feeder (10 cm in diameter x 45 cm long) with 2.54-cm wire mesh on which feeding
birds could perch, feeder 8 was a house-shaped, wood and plexiglass feeder hung
from the branch of a tree, and feeder 9 was a cylindrical feeder (6.5 cm in diameter
x 36 cm long) designed to dispense thistle seed and hung from the end of a wooden
swing frame. Each type of feeder was commonly available in the test area. Feeders
1–8 were filled with a seed mixture commercially available and designed to attract a
variety of birds. The thistle feeder was filled with thistle. Feeder numbers 1 through
6 were erected at the start of this experiment; numbers 7, 8, and 9 had been in use on
the property previously. A wheelbarrow was placed under the feeders during filling.
Although this may not be typical, it limited the source of seed beneath the feeders to
that caused by feeding, not filling.
The locations were sampled with a 0.5-m2 flag. The flag consisted of a 1-m wide
by 0.5-m long piece of flannel cloth whose leading edge was tacked to a 1.05-m
wooden dowel to which a 2-m length of nylon string was attached (Falco and Fish
1992). The flag was subsequently dragged over the surface in a circle with the spot
directly below the feeder as the center. This procedure resulted in a sampled area of
about 3.2 m2. The flag was dragged over the control area in the same manner. It was
marked with a plastic tent peg at 1.1 m from the center. The flag was inspected for
ticks after dragging at each station. All ticks were removed from the flag, preserved
in alcohol, and identified to species level (Keirans and Litwak 1989, Keirans et al.
1996). A total of 38 sampling events was spread out over 11 of the 24 months in that
time period: August, September, and November of 2005; July, August, October, November,
and December of 2006; and May, June, and July of 2007.
Table 1. Amount and density of Ixodes scapularis collected at bird feeders and control areas on
a residential lawn in Worcester County, MA.
Number (n) Larvae Nymph Adult Density (ticks/m2) Percent
Feeders 10 7 3 0 0.0091 83
Controls 2 2 0 0 0.0018 17
Totals 12 9 3 0 0.0055*
*Average.
2008 Northeastern Naturalist Notes 471
Results. A total of 12 live Blacklegged Ticks was collected. All of the ticks were
collected in 2005 and 2007. There where significantly more ticks collected from beneath
the feeders than from the control areas (Mann-Whitney, P = 0.035). Ticks were
collected from under 6 of the 9 feeders (67%) and 2 of the 9 control areas (22%). All the
ticks collected were sub-adults. The ticks from under the feeders were larvae (n = 7)
and nymphs (n = 3), and those from the control areas were larvae (n = 2) (Table 1).
Discussion. Our collection of only sub-adult stages is consistent with published
data of ticks collected from passerines (Hyland et al. 2000, Scharf 2004) and small
mammals (Mather et al. 1989, Schmidt et al. 1999) that indicate that sub-adult ticks
are more likely than adults to parasitize smaller vertebrates. The possibility that
rodents and medium-sized mammals could be attracted to the seed that falls beneath
bird feeders has been considered by others (Orloski et al. 1998, Townsend et al.
2003). Host-seeking Blacklegged Tick nymphs are unlikely to travel far (less than 5 m) from
where they have dropped off or were groomed off a vertebrate host (Carroll and
Schmidtmann 1996, Falco and Fish 1991).
We hypothesized that the activity of small mammals and birds foraging on the
ground in the immediate vicinity of bird feeders on residential properties could affect
the density of questing ticks relative to the rest of the lawn. Both birds and mammals
can be potential sources of ticks found on lawns as well as vehicles for removal of ticks
that may be questing there. If the net effect was to leave more ticks than they removed
as our results indicate, it could increase the likelihood of residents being bitten as a result
of maintaining the feeders or engaging in other activities close to them.
While the resulting distribution could increase the likelihood of residents of
premises with bird feeders being bitten by a tick, it may not significantly increase the
risk of Lyme disease. Of the ticks collected from under the feeders, 70% (7/10) were
larvae. Since Blacklegged Ticks usually do not acquire B. burgdorferi transovarially
(Piesman et al. 1986), larvae are unlikely to be infected with the spirochete.
The total number of ticks collected was low (n = 12), but the actual number of
ticks present could have been higher because flagging only captures a small proportion
of the ticks present (Daniels et al. 2000). The low number of collected ticks may
have also been due in part to the inhospitable nature of a typical residential lawn to
tick survival. Manicured lawns can be a suitable environment for Blacklegged Ticks
(Falco and Fish 1988), but are not ideal. The low humidity that results from the artificially maintained height of a lawn and subsequent lack of shade is consistent with
high mortality (Jones and Kitron 2000, Stafford 1994) and reduced questing (Schulze
et al. 2001). Further fine-scale sampling of residential properties with bird feeders
should improve our understanding of how vertebrates attracted to the feeders affect
tick distribution on such premises.
Acknowledgments. We would like to thank W. Wyatt Hoback for his guidance at the
inception of this project and two anonymous reviewers for comments on the manuscript.
Literature Cited
Burgdorfer, W., A.G. Barbour, S.F. Hayes, J.L. Benach, E. Grunwaldt, and J.P. Davis. 1982.
Lyme disease: A tick-borne spirochetosis? Science 216(4552):1317–1319.
Carroll, J.F., and E.T. Schmidtmann. 1996. Dispersal of Blacklegged Tick (Acari: Ixodidae)
nymphs and adults at the woods-pasture interface. Journal of Medical Entomology
33(4):554–558.
Center for Disease Control and Prevention (CDC). 2006. Reported Lyme disease cases by state,
1993–2005. Available online at http://www.cdc.gov/ncidod/dvbid/lyme/ld_rptdLymeCasesbyState.
htm. Accessed April 17, 2007.
472 Northeastern Naturalist Notes Vol. 15, No. 3
Daniels, T.J., R.C. Falco, and D. Fish. 2000. Estimating population size and drag-sampling
efficiency for the Blacklegged Tick (Acari: Ixodidae). Journal of Medical Entomology
37(3):357–363.
Falco, R.C., and D. Fish. 1988. Prevalence of Ixodes dammini near the homes of Lyme
disease patients in Westchester County, New York. American Journal of Epidemiology
127(6):826–830.
Falco, R.C., and D. Fish. 1991. Horizontal movement of adult Ixodes dammini (Acari: Ixodidae)
attracted to CO2-baited traps. Journal of Medical Entomology 28(5):726–729.
Falco, R.C., and D. Fish. 1992. A comparison of methods for sampling the Deer Tick, Ixodes
dammini, in a Lyme disease endemic area. Experimental and Applied Acarology
14:165–173.
Frank, F.H., D. Fish, and H. Moy. 1998. Landscape features associated with Lyme disease risk
in a suburban residential environment. Landscape Ecology 13:27–36.
Hyland, K.E., J. Bernier, D. Markowski, A. MacLachlan, Z. Amr, J. Pitocchelli, J. Myers, and
R. Hu. 2000. Records of ticks (Acari: Ixodidae) parasitizing birds (Aves) in Rhode Island,
USA. International Journal of Acarology 26(2):183–192.
Jones, C.J., and U.D. Kitron. 2000. Populations of Ixodes scapularis (Acari: Ixodidae) are
modulated by drought at a Lyme disease focus in Illinois. Journal of Medical Entomology
37(3):408–415.
Keirans, J.E., and T.R. Litwak. 1989. Pictorial key to the adults of hard ticks, Family Ixodidae
(Ixodidae: Ixodoidea), east of the Mississippi river. Journal of Medical Entomology
26(5):435–448.
Keirans, J.E., H.J. Hutcheson, L.A. Durdan, and J.S.H. Klompen. 1996. Ixodes (Ixodes) scapularis
(Acari: Ixodidae): Redescription of all active stages, distribution, hosts, geographical
variation, and medical and veterinary importance. Journal of Medical Entomology
33(3):297–318.
Mather, T.N., M.L. Wilson, S.I. Moore, J.M.C. Ribeiro, and A. Spielman. 1989. Comparing the
relative potential of rodents as reservoirs of the Lyme disease spirochete (Borrelia burgdorferi).
American Journal of Epidemiology 130(1):143–150.
Orloski, O.A., G.L. Campbell, C.A. Genese, J.W. Beckley, M.E. Schriefer, K.C. Spitalney, and
D.T. Dennis. 1998. Emergence of Lyme disease in Hunterdon County, New Jersey, 1993:
A case-control study of risk factors and evaluation of reporting patterns. American Journal
of Epidemiology 147(4):391–397.
Piesman, J., J.G.Donahue, T.N. Mather, and A. Spielman. 1986. Transovarially acquired
Lyme disease spirochetes (Borrelia burgdorferi) in field-collected larval Ixodes dammini
(Acari:Ixodidae). Journal of Medical Entomology 33(20):219.
Scharf, W.C. 2004. Immature ticks on birds: Temporal abundance and reinfestation. Northeastern
Naturalist 11(2):143–150.
Schmidt, K.A, R.S. Osfeld and E.M. Shauber. 1999. Infestation of Peromyscus leucopus and
Tamias striatus by Ixodes scapularis (Acari: Ixodidae) in relation and abundance of hosts
and parasites. Journal of Medical Entomology 36(6):749–757.
Schulze, T.L., R.A. Jordan, and R.W. Hung. 2001. Effects of meteorological factors on diurnal
questing of Ixodes scapularis and Amblyomma americanum (Acari: Ixodidae). Journal of
Medical Entomology 38(2):318–324.
Smith, G., E.P. Wileyto, R.B. Hopkins, B.R. Cherry, and J.P. Mayer. 2001. Risk factors for
Lyme disease in Chester County, Pennsylvania. Public Health Report 16:146–156.
Stafford III, K.C. 1994. Survival of immature Ixodes scapularis (Acari: Ixodidae) at different
relative humidities. Journal of Medical Entomology 31(2):310–314.
Townsend, A.K., R.S. Ostfeld, and K.B. Geher. 2003. Effects of bird feeders on Lyme disease
prevalence and density of Ixodes scapularis (Acari: Ixodidae) in a residential area of
Dutchess County, New York. Journal of Medical Entomology 40(4):540–546.
1Biology Department, Tri-County RVTHS, Franklin, MA 02038. 2University of Nebraska at
Kearney, Bruner Hall, 905 West 25th Street, Kearney, NE 68849. *Corresponding author - kowalczykjp@
unk.edu.