Rabbit Population Densities at the Sevilleta National Wildlife Refuge, New Mexico (1992-2004)

This study measured the population dynamics of black-tail jackrabbits (Lepus californicus) and desert cottontail rabbits (Sylvilagus auduboni) in the grasslands and creosote shrublands of McKenzie Flats, Sevilleta National Wildlife Refuge.  The study was begun in January, 1992, and continued quarterly each year.  Rabbits were sampled via night-time spotlight transect sampling along the roads of McKenzie Flats during winter, spring, summer, and fall of each year.  The entire road transect was 21.5 miles in length. Measurements of perpendicular distance of each rabbit from the center of the road were used to estimate densities (number of rabbits per square kilometer) via Program DISTANCE.  Results from 1992 to 2002 indicated that spring was the peak density period of the year, with generally steady declines through the year until the following spring. Evidence of a long-term "cycle" (e.g., the 11 year cycle reported for rabbits in the Great Basin Desert) did not appear in the Sevilleta rabbit populations.

本研究针对塞维利亚特国家野生动物保护区麦肯齐平原的草原与石炭酸灌木灌丛生境中的黑尾长耳大野兔（Lepus californicus）和荒漠棉尾兔（Sylvilagus auduboni）的种群动态开展监测。本研究于1992年1月启动，此后每年按季度持续进行。研究人员于每年冬、春、夏、秋四季，沿麦肯齐平原的道路开展夜间灯光样线调查以采集野兔样本，整条道路样线总长21.5英里。通过记录每只野兔距道路中线的垂直距离，借助DISTANCE程序（Program DISTANCE）估算种群密度（单位：只/平方千米）。1992至2002年的监测结果显示，春季为全年种群密度峰值期，全年种群密度整体呈逐步下降趋势，直至次年春季。此外，未在塞维利亚特保护区的野兔种群中观测到大盆地沙漠野兔种群所报道的长期‘周期波动’（例如11年周期）。