SMALL MAMMAL POPULATIONS IN A RECENTLY ESTABLISHED
MITIGATION
WETLAND

Shannon Kass, Parisa Hajaliakbari, Stacy Svoboda, and
Tina Kocer
Environmental Sciences Program, University of Dubuque,
2000 University Avenue, Dubuque, Iowa  52001

The reclamation of land for subsequent use in the
construction of mitigation wetlands has increased
throughout the Upper Mississippi River Valley. 
Monitoring of the spread of natural populations into
previously unoccupied habitat is an important step in
the in the determination of the success or failure of
the project.  Small mammal populations are key in the
establishment of terrestrial vertebrate ecosystems.  We
censured the small mammal populations and habitat use
in the Schmitt Island Wetland Area, Dubuque, Iowa in
Fall 1994, 1995, and 1996, as well as Spring 1995.  Our
initial hypothesis was that small mammal species
density would be similar in the two major habitat
types, forest and grassland, and the ecotone area
between.  We also tested for differences in population
numbers and structure between these habitat types,
using a mark-recapture study.  In 1996, we expanded the
project to include the use of PIT tags for detecting
overwintering survival and movement.  We found that the
major species using the area was the northern deer
mouse, Peromyscus maniculatus.

Small mammal habitat use was heaviest in the ecotone
and woods areas.  Little use of the grassland habitat
was recorded.  The primary dispensers into the area
appeared to be subadult males based on recorded sizes
and weights, although pregnant females were captured in
Fall 1996.  The small number of recaptures indicates
either a large population of deer mice in the area, or
perhaps more likely, dispersal into or through the
region during the time of greatest population in
surrounding areas.  Also of interest is the lack of
voles in the grassland area.  This suggests that
recolonization has only just begun for this species
following the summer floods of 1993.
Keywords:  small mammals, populations, Peromyscus, PIT
tags, succession

Shannon Kass
University of Dubuque
Dubuque, Iowa
(319)589-3598
Fax (319)556-8633
email skass@univ.dbq.edu
Poster
Student Author