SEASONAL TIMING OF FROG AND TOAD BREEDING ACTIVITY IN
EASTERN IOWA

Kelly J. McKay
Midwest Raptor Research Fund, Moline, IL 61265

I have conducted 3 frog and toad breeding chorus surveys in east central Iowa since
1993, as part of the Iowa Department of Natural Resources' state-wide monitoring
program.  These survey routes are located within two counties (Scott and Clinton)
immediately adjacent to the Mississippi River.  Each route was sampled 3 times
during the amphibian breeding season (early, middle, and late).  During the
10-minute point counts, all identified species were recorded and each was assigned
a relative abundance score ranging from 1 to 3.  A Code 1 resulted if individual
animals could be identified and there was no overlapping between calls.  A Code 2
was scored if individuals could still be identified, but with considerable
overlapping between calls.  A Code 3 was assigned if individuals could no longer
be distinguished and the calls were constant, continuous, and overlapping.  A total
of 10 species have been identified over a 4 year period (1993-1996).  For the
purpose of analysis, data from the 3 individual routes were combined and grouped
into the 3 survey time periods.  Consequently, I was able to examine the seasonal
timing of breeding activity for each species based on the relative amount of
breeding chorus activity occurring.  During Time Period 1, 6 species were
encountered.  Of these, a large proportion of the overall abundance of 3 species
were engaged in breeding chorus activities including:  the western chorus frog
(Pseudacris triseriata) (58%), northern leopard frog (Rana pipiens) (80%), and the
pickerel frog (Rana palustris) (100%).  Nine species were identified during Time
Period 2.  Again, a large portion of the overall abundance of 3 species were calling
at this time including:  the American toad (Bufo americanus) (52%), eastern gray
treefrog (Hyla versicolor) (42%), and the cope's gray treefrog (Hyla chrysoscelis)
(59%).  Similarly, 9 species were identified during Time Period 3.  However,
during this period a large proportion of the overall abundance of 6 species were
participating in breeding choruses including:  both the eastern and cope's gray
treefrogs (53% and 41%, respectively), spring peeper (Pseudacris crucifer) (56%),
cricket frog (Acris crepitans) (82%), green frog (Rana clamitans) (81%), and the
bullfrog (Rana catesbeiana) (95%).  In conclusion, each species seems to prefer
certain seasonal time periods for engaging in breeding chorus activities.  This
chronology may prove useful in efforts to manage and monitor, on a long-term
basis, the anuran species inhabiting Iowa.

Keywords:  frogs and toads, breeding choruses, seasonal timing, anurans,
Mississippi River


1)  Kelly J. McKay, Midwest Raptor Research Fund, 6143 34th. Avenue, Moline,
IL 61265.
Phone: (309) 792-5981.  FAX: not available.  E-mail: not available.
2)  Poster Presentation; not able to convert format.
3)  Not a student paper.