Predicting river otter latrine sites in Pennsylvania

Thomas J. Swimley, Thomas L. Serfass, Robert P. Brooks, Walter M. Tzilkowski

Research output: Contribution to journalArticlepeer-review

45 Scopus citations


Detecting river otter (Lontra canadensis) presence or estimating abundance relies on harvest records, trapper surveys, track surveys, or latrine surveys. Harvest records and trapper surveys are not an option where otters are protected, and track surveys have limited utility in many areas. Latrine surveys are often useful, but may be labor intensive. We used multivariate analysis techniques to examine habitat characteristics at 131 river otter latrines and 113 randomly chosen (nonlatrine) sites along upper Pine Creek, northcentral Pennsylvania, 1991-1992. Discriminant analysis and logistic regression each identified 6 variables as predictors of otter latrine sites: vertical banks, rock formations, points of land, backwater sloughs, tributary streams, and beaver (Castor canadensis) bank dens, lodges, or ponds. Models were cross-validated with ground surveys and low-altitude aerial photographs (1:1,300) from lower Pine Creek, 1993-1994, and Tionesta Creek, northwestern Pennsylvania, 1993-1994. We developed a pattern recognition (PATREC) model using the 6 variables identified as predictors of river otter latrines. Results were similar for all 3 model types, but differed among the 3 survey areas. All 3 model types showed potential for identifying latrines. Allocation of resources to detect otter presence can be adjusted by varying the cutpoint P(E), that defines a predicted latrine for both the logistic regression and the PATREC models.

Original languageEnglish (US)
Pages (from-to)836-845
Number of pages10
JournalWildlife Society Bulletin
Issue number4
StatePublished - Dec 1 1998

All Science Journal Classification (ASJC) codes

  • Nature and Landscape Conservation


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