Juvenile male American Kestrel hunting Green Darner
by Michael King
Last September, while visiting a hawkwatch in
southern Ontario, did you notice hordes of migrating
Monarch Butterflies and dragonflies? Green Darners (Anax
junius) are large robust dragonflies that follow the
shores of Lake Ontario and Lake Erie as they migrate
south (Walker, E. 1958. The
Odonata of Canada and Alaska.
Volume 11. University of Toronto Press, 129-130). This
is a similar flight path to that of migrating hawks, but
is there any significance to them following the same
route? During fall migration,
Kestrels and Merlins eat Green Darners.
September 1995, at Hawk Ridge, the famous hawkwatch site
in Duluth, Minnesota, veteran hawkwatcher, Frank
Nicoletti, studied the relationship between hawks and
Green Darners (The Loon
216-221, Winter 1996-97). He collected data showing that
favourable weather conditions for hawk migration also
concentrated large numbers of migrating Green Darners.
High counts of American Kestrels and Merlins correlated
with high counts of Green Damers. In fact, 88 percent of
American Kestrels counted between September and November
1995, migrated during September, coinciding with peak
darner migration counts. When the winds shifted, the
falcons and darners also shifted to the same flight
During September 1995, Nicoletti graphed the numbers of
hawks feeding on Green Darners. As they passed Hawk
Ridge, 28 percent of American Kestrels fed on Green
Darners, with the percentage increasing from none early
in the day to 73 percent in late afternoon. Later in the
day, the number of kestrels diminished but there was a
dramatic increase in the percentage feeding on Green
Darners. There were many more darners in late afternoon.
the same study, 14 percent of Merlins hunted and ate
darners. Migrating Merlins eat primarily birds, but
Green Darners are an important secondary food source.
The relationship between Merlins and Green Darners was
not as strong as that of American Kestrels and Green
few Sharp-shinned Hawks, Peregrine Falcons and three
Mississippi Kites also were observed hawking insects.
theorized that Green Darners constitute a major prey
for American Kestrels,
and that juvenile kestrels are particularly dependent on
this food source. While in the nest, young American
Kestrels are fed many insects as part of their diet.
they fledge, they feed primarily on insects. Their
inexperience catching birds and small mammals makes them
more dependent on an abundance of easy-to-catch darners.
Juvenile American Kestrels appear to time their first
southward migration to coincide with peak numbers of
migrating Green Darners.
summary, American Kestrels, especially the juveniles,
time their first southward migration to coincide with
peak numbers of migrating Green Darners. Are any Ontario
hawkwatchers studying Green Darners?
in OFO News Vol. 16 No. 1, Page 12. February 1998