conservation.arizona.edu - middens

Posthumus, E. E., J. L. Koprowski, and R. J. Steidl. 2015. Red squirrel middens influence abundance but not diversity of other vertebrates. PLoS ONE 10(4):e0123633. doi:10.1371/journal/pone.0123633.

thackerk1 — Wed, 24 Jul 2019 23:22:26 +0000

Authors

Erin E. Posthumus

John L. Koprowski

Robert J. Steidl

Some animals modify the environment in ways that can influence the resources available to other species. Because red squirrels (Tamiasciurus hudsonicus) create large piles of conifer-cone debris (middens) in which they store cones, squirrels concentrate resources that might affect biodiversity locally. To determine whether other animals are attracted to midden sites beyond their affinity for the same resources that attract red squirrels, we assessed associations between middens, mammals, and birds at population and community levels. We surveyed 75 middens where residency rates of red squirrels varied during the previous five years; sampling along this residency gradient permitted us to evaluate the influence of resources at middens beyond the influence of a resident squirrel. At each loca- tion, we quantified vegetation, landscape structure, abundance of conifer cones, and midden structure, and used capture–recapture, distance sampling, and remote cameras to quantify presence, abundance, and species richness of mammals and birds. Red squirrels and the resources they concentrated at middens influenced mammals and birds at the population scale and to a lesser extent at the community scale. At middens with higher residency rates of red squirrels, richness of medium and large mammals increased markedly and species richness of birds increased slightly. After accounting for local forest characteristics, however, only species richness of medium-to-large mammals was associated with a red squirrel being resident during surveys. In areas where red squirrels were resident during surveys or in areas with greater amounts of resources concentrated by red squirrels, abundances of two of four small mammal species and two of four bird species increased. We conclude that the presence of this ecosystem modifier and the resources it concentrates influence abundance of some mammals and birds, which may have implications for maintain- ing biodiversity across the wide geographic range inhabited by red squirrels and other larderhoarding animals.

Additional Information

Red Squirrel Middens Influence Abundance but Not Diversity of Other Vertebrates

Date of publication:

2015

Topics

red squirrel

resources

middens

Mammals

birds

population

community levels

residency

Edelman, A. J., J. L. Koprowski, and J. L. Edelman. 2005. Kleptoparasitic behavior and species richness at Mt. Graham red squirrel middens. USDA Forest Service Proceedings RMRS-P-36: 395 - 398.

thackerk1 — Tue, 25 Jun 2019 01:31:05 +0000

Authors

Andrew J. Edelman

John L. Koprowski

Jennifer L. Edelman

We used remote photography to assess the frequency of inter- and intra-specific klepto- parasitism and species richness at Mt. Graham red squirrel (Tamiasciurus hudsonicus grahamensis) middens. Remote cameras and conifer cones were placed at occupied and unoccupied middens, and random sites. Species richness of small mammals was higher at red squirrel middens than random sites. Abert’s squirrels, potential kleptoparasites, were recorded only at unoccupied mid- dens and random sites. Non-resident red squirrels were most common at unoccupied middens and rare at occupied middens and random sites. Inter- and intra-specific kleptoparasitism of red squirrel middens appears uncommon likely due to territorial behavior.

Additional Information

Kleptoparasitic Behavior and Species Richness at Mt. Graham Red Squirrel Middens

Date of publication:

2005

Topics

Mount Graham Red Squirrel

kleptoparasitism

inter-specific

intra-specific

conifer cones

small mammals

middens

Abert’s squirrels

territorial behavior

species richness

Blount, S.J., J.L. Koprowski. 2012. Small mammal response to post-fire conditions: case of the endangered Mount Graham red squirrel. Southwestern Naturalist. 57:8-15.

thackerk1 — Thu, 20 Jun 2019 21:50:31 +0000

Authors

Seafha J. Blount

John L. Koprowski

To assess response of Mount Graham red squirrels (Tamiasciurus hudsonicus grahamensis) to postfire conditions, we monitored size of home ranges and core areas and characteristics of vegetation at middens in an area of low-intensity burn. For a larger-scale assessment, we monitored mountain-wide occupancy of middens. Although red squirrels selected unburned locations as sites for middens, mean size of home range in a lightly burned area decreased over time, suggesting high availability of resources in lightly burned areas.

Additional Information

Response of the Mount Graham Red Squirrel to Postfire Conditions

Date of publication:

2012

Topics

Mount Graham Red Squirrel

home range

vegetation

middens

burn areas

unburned areas