Does repeated human intrusion alter use of wildland sites by red squirrels? Multiyear experimental evidence

intrusion by humans into wildlife habitat during recreational activities has become a worldwide conservation concern. Low levels of intrusion, which occur frequently in many wildlands, could influence use of sites by red squirrels (Tamiasciurus hudsonicus) and have important ramifications for conservation. Red squirrels can influence forest composition and regeneration by feeding on conifer buds, seeds, and vascular tissues, and they prey on avian nests. Attraction of red squirrels could increase the risk of these activities, whereas displacement of red squirrels may exacerbate demographic problems for small populations of red squirrels in isolated habitats. We implemented experimental intrusions during 10 consecutive weeks of the red squirrel breeding season, 1 or 2 times/week (1990-1993) in I area and 5 times/week (1991-1993) in another area in Wyoming. Each intrusion lasted 1 h and involved I person. Abundance of red squirrels at intruded sites did not differ significantly from that at control sites during either experiment. However, experiments should be conducted to examine longer-term effects and effects of higher levels of intrusion because alteration of distributions of red squirrels may affect forest conditions and demographics or fitness of birds and red squirrels.