Estimating snowshoe hare population density from pellet plots: a further evaluation

Abstract

We counted fecal pellets of snowshoe hares (Lepus americanus) once a year in 10 areas in the southwestern Yukon from 1987 to 1996. Pellets in eighty 0.155-m 2 quadrats were counted and cleared each June on all areas, and we correlated these counts with estimates of absolute hare density obtained by intensive mark-recapture methods in the same areas. There is a strong relationship between pellet counts and population density (r = 0.76), and we present a predictive log-log regression to quantify this relationship, which improves on our previously published 1987 regression, particularly at low hare densities. The precision of density estimates can be improved most easily by increasing the number of sets of quadrats in an area (one set = 80 plots), rather than increasing the number of plots counted within one set. The most important question remaining concerns the generality of this relationship for snowshoe hares living in other habitats in the eastern and southern portions of their geographic range.Résumé : Nous avons compté les boulettes fécales de Lièvres d'Amérique (Lepus americanus) une fois l'an en 10 zones du sud-ouest du Yukon, de 1987 à 1996. Les boulettes ont été comptées chaque juin, puis retirées, dans quatre-vingt quadrats de 0,155 m 2 dans chacune des zones; par la suite, ces nombres ont été mis en corrélation avec des estimations de la densité absolue des lièvres obtenues par des méthodes intensives de capture-recapture dans les mêmes zones. Il y a une forte corrélation entre le nombre de boulettes et la densité de la population (r = 0,76) et nous présentons ici une régression log-log prédictive pour quantifier cette relation, ce qui rend plus robuste la régression que nous avons publiée en 1987, particulièrement lorsque la densité des lièvres est faible. La précision des estimations de la densité peut être raffinée davantage en augmentant le nombre d'ensembles de quadrats dans une région (1 ensemble = 80 parcelles), plutôt que le nombre de parcelles dans chaque ensemble. Il reste à déterminer à quel point cette relation est gé-néralisée chez les lièvres qui vivent dans d'autres habitats dans les portions est et sud de leur répartition.[Traduit par la Rédaction] 4Krebs et al.

Multiscale habitat relationships of snowshoe hares (Lepus americanus) in the mixed conifer landscape of theNorthernRockies,USA: Cross‐scale effects of horizontal cover with implications for forest management

“…These pellet counts were on uncleared plots and provided our metric of snowshoe hare occupancy (≥1 pellet) and intensity of use (i.e., mean number of pellets/subplot). Many studies have confirmed the positive relationship between snowshoe hare density and pellet counts (e.g., Berg & Gese, ; Krebs et al., ; Krebs, Boonstra et al., ; Mills et al., ; Murray, Ellsworth, & Zack, ); thus, it was conservative and appropriate to use pellets as a measure of intensity of use. We visited our sampling locations only once; therefore, we did not estimate detection probabilities for occupancy (sensu MacKenzie et al., ).…”

“…We sampled snowshoe hares by enumerating snowshoe hare pellets within five 5.1 × 305 cm subplots (Krebs, Gilbert, Boutin, & Boonstra, ; Krebs, Boonstra et al., ) placed at plot center and the four edges of our 20 × 20 m plot. These pellet counts were on uncleared plots and provided our metric of snowshoe hare occupancy (≥1 pellet) and intensity of use (i.e., mean number of pellets/subplot).…”

Effects of stand structure and landscape characteristics on habitat use by birds and small mammals in managed boreal forest of eastern Canada

“…Such abundance indices are widely used for hares (Krebs et al 2001;Murray et al 2002) and more recently for grouse (Potvin et al 2001;Huggard 2003). Such abundance indices are widely used for hares (Krebs et al 2001;Murray et al 2002) and more recently for grouse (Potvin et al 2001;Huggard 2003).…”

Bridging native and scientific observations of snowshoe hare habitat restoration after clearcutting to set wildlife habitat management guidelines on Waswanipi Cree land

“…The relative abundance of pellets found within each experimental site is proportional to hare population density and was measured by means of pellet counts (Krebs et al 2001). Systematic pellet counting was achieved by placing, in the center of each experimental site, 30 microplots of 4 m 2 each, along a 500 m equilateral triangle transect, at 50 m intervals.…”