Banding Raptors
at the Nature Area
The
Grosse Ile Nature and Land Conservancy (GINLC) has helped support
raptor banding in the Grosse Ile Nature Area since 2004.
Raptor
banding is a process in which hawks are captured, banded, and
weighed in order to obtain information on the health of ecosystems.
Raptors are high on the food chain, and thus the health of their
population is indicative of the overall state of an ecosystem.
Monitoring raptor populations is important for the conservation
of the many plants and animals within an ecosystem.
Thomas
Carpenter, Ph.D. and Arthur Carpenter have been banding hawks
in the Great Lakes area since 1981. Most northern raptor populations
are migratory. Therefore, their populations can most easily
be studied through counting and banding in areas that concentrate
migrant birds. Monitoring raptors during this time is crucial
for the preservation and protection of their populations and
the ecosystems they dominate.
The
shorelines of the Great Lakes concentrate migrant raptors during
fall and spring migration because most hawks avoid crossing
large bodies of water. Thomas and Arthur have banded raptors
during fall migration along the northwest and west shores of
Lake Erie and the southern Detroit River, at Point Mouillee
State Game Area, Lake Erie Metropark, and the Grosse Ile Nature
Area in Michigan and Holiday Beach in Ontario.
Raptor
banding enables researchers to determine the age and sex composition
of migrant raptors, patterns of migration of the different age
and sex groups, longevity and the causes of death of migrant
raptors, migration routes of raptors, and the breeding and wintering
areas of migrant raptors.
In
addition to establishing this information, Thomas and Arthur
also have goals of determining changes in eye color, weight,
and feather wear through recapturing already banded raptors
and determining the rate of migration of raptors by recapturing
hawks on Grosse Ile that were originally banded along the north
shore of Lake Erie earlier in migration. The information obtained
from these goals aids in the overall conservation of each hawk
species.
Raptor
banding is an eco- and animal-friendly process. Thomas and Arthur
wait in a clearing over which hawks frequently pass, concealed
from sight behind a blind. They have several lure birds outside
of the blind that are enclosed in a specially designed leather
harness that is attached to a lure line. Upon sighting a hawk,
the men pull the lure line which elevates the lure bird, causing
it to fly. The flying bird attracts the hawk, causing it to
approach. The lure birds are protected by two to three mist
nets that capture hawks when they swoop down trying to catch
their prey, thereby keeping the lures from harm.
When
a hawk is attracted to one of the birds in the clearing and
dives to catch its prey, it gets caught in the barely-visible
mist netting surrounding the lure field. The men immediately
remove the hawk from the netting, place it in a can (the can
restrains the hawk without harming it), and proceed to band,
weigh, and measure it. Eye color and other noteworthy characteristics
are recorded. The raptor is released unharmed within 10 minutes.
Since
2004, one Red-shouldered Hawk, two American Kestrels, two Northern
Harriers, 11 Sharp-shinned Hawks, 13 Cooper's Hawks, and 44
Red-tailed Hawks have been banded. Overall at this site, the
Carpenters have banded and recorded valuable information about
73 hawks during the time period, a significant number that will
enhance future research.
The
GINLC will continue to aid Thomas and Arthur in their quest
by helping to prepare banding site and providing access to the
Grosse Ile Nature Area, increasing the chance for conservation
of important raptor species.
Year
|
Species
|
Total
|
Northern
Harrier
|
Red-shouldered
Hawk
|
Red-tailed
Hawk
|
American
Kestrel
|
Sharp-shinned
Hawk
|
Cooper's
Hawk
|
2004
|
1
|
|
6
|
1
|
2
|
2
|
12
|
2005
|
|
|
6
|
|
1
|
2
|
9
|
2006
|
|
1
|
3
|
1
|
5
|
5
|
15
|
2007
|
1
|
|
29
|
|
3
|
4
|
37
|
Total
|
2
|
1
|
44
|
2
|
11
|
13
|
73
|