Explanation, Procedures, Data Files and Publications
For Blarina brevicauda I present only the estimated numbers present in
each habitat each month of the study, as estimated by Minimum Known
Alive method. There were too few captures most months to justify entry
of individual captures. Compilations of proportion reproductive and
survival rates are available in the published papers and manuscript.
Procedures - Data analysis
Of the 7,203 individuals captured during the study, 1,933 (26.8%) were
dead at first capture. Another 957 were found dead in traps at
subsequent captures, for a total trap mortality of 40.1%. While
obviously having an impact upon the populations, trap mortality did not
appear to disrupt overall dynamics of our study population or unduly
bias our conclusions. B. brevicauda did not enter traps until at least
three-fourths grown so we could not distinguish young animals from
small adults; thus, we did not separate our data by age class.
Estimates of population density were compiled manually, based on the
minimum number known alive method (Krebs 1999). Owing to very few
captures for many months, often 1 or 2, or no captures at all, and few
repeated captures, other models of estimating population density were
not appropriate. Population data from all sites within each habitat
(Getz 1994) were combined for analysis. Thus, population densities
represent averages for all sites within each habitat.
Blarina brevicauda Data Files
1989. A fourteen year study of Blarina brevicauda populations in east-central Illinois. Jour. Mamm., 70:58-66.
1994. Population dynamics of the short-tailed shrew, Blarina brevicauda. In Advances in the biology of shrews. (J. J. Merritt, G. L. Kirkland and R. K. Rose, eds.). Bull Carnegie Museum. Pp. 27-38.
Population dynamics of the northern short-tailed shrew, Blarina brevicauda: insights from a 25-year study
Lowell L. Getz, Joyce E. Hofmann, Betty McGuire, and Madan K. Oli