Decline of the Endangered Morro Bay Kangaroo Rat in California

作者：Kofron Christopher P^*; Villablanca Francis X^*

来源：Journal of Fish and Wildlife Management, 2016, 7(1): 237-254.

DOI：10.3996/102014-JFWM-078

• Baywood Fine Sand
• California
• conservation-reliant
• Dipodomys heermanni morroensis
• endangered
• Morro Bay kangaroo rat

The Morro Bay kangaroo rat Dipodomys heermanni morroensis occurs in the vicinity of Morro Bay (specifically in and near Los Osos) in western San Luis Obispo County in coastal central California. It was listed as endangered pursuant to the U.S. Endangered Species Conservation Act in 1970 and subsequently the U.S. Endangered Species Act in 1973. Field research from the late 1950s to the mid-1980s has documented a rapid population decline. Despite many efforts, researchers have not captured the Morro Bay kangaroo rat since 1986, and the last captive individual died in 1993. We review the biology and conservation status of the Morro Bay kangaroo rat, including taxonomy and genetics, soil type and burrows, history of decline, primary causes of decline, breeding in the wild and in captivity, habitat restoration, and threats. In particular, there are two primary causes of decline. First, development (urban, agricultural, and industrial) has resulted in direct loss of habitat. Second, in the absence of fire, the early seral stages of coastal dune scrub (optimal habitat) have matured to later successional stages of vegetation, which are denser and with substantially fewer annual food plants, and which negatively impact the locomotion of kangaroo rats and change the diversity of the small mammal community with a likely increase in competition. In 2016 only pockets of habitat remain, with optimal habitat comprising an estimated 1% of the historical geographic range. Although researchers have not demonstrated predation by domestic cats, it is likely a major threat and we suspect it has contributed to the decline based upon a review of the literature. In 2011 we observed potential signs of the Morro Bay kangaroo rat at two historical areas, which suggests it may be persisting at extremely low densities in a few isolated colonies. In addition, we could not obtain permission to survey on four private properties with potential habitat. In consideration of the vast loss and fragmentation of its habitat, along with the continuing and pervasive threats, the Morro Bay kangaroo rat is clearly conservation-reliant. We believe that without urgent human intervention, the Morro Bay kangaroo rat will soon become extinct if it is not already.

• 出版日期2016-6