SGS-LTER Long-term Monitoring Project: Carnivore Scat Count on the Central Plains Experimental Range, Nunn, Colorado, USA 1997 -2006, , ARS Study Number 98

This data package was produced by researchers
working on the Shortgrass Steppe Long Term
Ecological Research (SGS-LTER) Project,
administered at Colorado State University.
Long-term datasets and background information
(proposals, reports, photographs, etc.) on the
SGS-LTER project are contained in a comprehensive
project collection within the Digital Collections
of Colorado
(http://digitool.library.colostate.edu/R/?func=collections&collection_id=3429).
The data table and associated metadata document,
which is generated in Ecological Metadata
Language, may be available through other
repositories serving the ecological research
community and represent components of the larger
SGS-LTER project collection. Additional information and referenced
materials can be found: http://hdl.handle.net/10217/83392 Carnivores are among the most conspicuous,
charismatic and economically important mammals in
shortgrass steppe, yet relatively is little is
known about their populations or of the ecological
factors that determine their distribution and
abundance, in part because densities tend to be
low. Mammalian carnivores represent the top
predators in grassland food webs, consuming
rodents, rabbits, young ungulates and other small
vertebrates. In addition, shortgrass steppe is the
primary habitat of the swift fox (Vulpes velox), a
species of special conservation concern throughout
most of its range. Fox populations are thought to
be limited by predation from coyotes (Canis
latrans), the most common carnivore in these
grasslands and a species of interest, both for its
ecological roles and well as a target species for
human exploitation, ie hunting and predator
control. In 1994, we implemented a low-intensity
sampling scheme to monitor long-term changes in
relative abundance of mammalian carnivores and
help us examine interactions between these
predators and their small mammal prey, including
rodents and rabbits. We estimated relative
abundance of carnivores using scat surveys along a
fixed route. Four times each year (January, April,
July, October), we drove a 32-km route consisting
of pasture two-track and gravel roads on the CPER.
We first drove the route to remove all scats
(‘PRE-census’); we then returned ~14 d later and
counted the number of scats deposited on the route
(‘CENSUS’). We recorded the species that deposited
the scat and estimated the scat age based on
external appearance (4 categories). Beginning in
1997, we recorded the vegetation (habitat) type
and topographic position of all scat locations to
describe habitat use. Latrines are indicated by
locations containing multiple scats. We used the
‘CENSUS’ data to calculate a scat index, defined
as the number of scats deposited per km of road
per night. The scat index can be used to estimate
population density using equations for coyotes
(Knowlton 1982) and swift foxes (Schauster et al.
2002) that described the rate of scat deposition
from surveys where density was known. To estimate
density and compare trends among seasons and
years, we omitted scats collected along the 8.3 km
of the route that occurred on gravel county roads.
These roads are graded sporadically, sometimes
between pre-census and census surveys, which
tended to remove scats. (NOTE: these observations
are NOT omitted in the dataset).

本数据集由供职于科罗拉多州立大学管理的短草草原长期生态研究（Shortgrass Steppe Long Term Ecological Research, SGS-LTER）项目的研究人员编制。SGS-LTER项目的长期数据集及背景资料（提案、报告、照片等）收录于科罗拉多数字馆藏的综合项目馆藏中，访问链接为：http://digitool.library.colostate.edu/R/?func=collections&collection_id=3429。数据表格及以生态元数据语言（Ecological Metadata Language）生成的关联元数据文档，亦可通过服务于生态研究社区的其他仓储获取，属于更大范围的SGS-LTER项目馆藏的组成部分。更多信息及参考资料可访问：http://hdl.handle.net/10217/83392。

食肉目动物是短草草原中最醒目、最具魅力且经济价值最高的哺乳动物类群之一，但目前对其种群数量及决定其分布与丰度的生态因子所知甚少，部分原因在于其种群密度通常较低。哺乳纲食肉动物是草原食物网中的顶级捕食者，以啮齿类、兔类、幼年有蹄类及其他小型脊椎动物为食。此外，短草草原是草原狐（Vulpes velox）的主要栖息地，该物种在其大部分分布范围内均为重点保护关注对象。有研究认为狐类种群受郊狼（Canis latrans）捕食限制，郊狼是这类草原中最常见的食肉动物，其不仅具有重要的生态作用，同时也是人类捕猎及捕食控制的目标物种。

1994年，本研究启动了低强度采样方案，以长期监测哺乳纲食肉动物的相对丰度变化，并助力探索这些捕食者与小型哺乳类猎物（包括啮齿类与兔类）之间的相互作用。研究人员沿固定路线开展粪便调查，以此估算食肉动物的相对丰度。每年开展四次调查（1月、4月、7月、10月），行驶总长32公里的路线，该路线涵盖CPER区域内的牧场两车道土路与碎石公路。研究人员首先沿路线行驶以清除所有现存粪便（即“预普查”阶段）；约14天后返回，统计路线上新遗留的粪便数量（即“普查”阶段）。研究人员记录粪便的产生物种，并依据外观将粪便年龄划分为4个等级。自1997年起，研究人员还记录了所有粪便发现点的植被（生境）类型与地形位置，以描述生境利用情况。粪便堆积点指存在多枚粪便的点位。

研究人员利用“普查”阶段的数据计算粪便指数，该指数定义为每公里道路每夜遗留的粪便数量。借助已知种群密度的调查中得到的粪便沉积速率公式，可通过粪便指数估算郊狼（Knowlton 1982）与草原狐（Schauster et al. 2002）的种群密度。为估算种群密度并对比不同季节与年份的变化趋势，研究人员剔除了沿8.3公里碎石县道收集的粪便数据。这类县道会不定期进行路面平整，有时会在预普查与普查阶段之间进行作业，从而可能清除粪便。（注：本数据集未剔除上述观测数据。）