Movement rules for herbivores in spatially heterogeneous environments: responses to small scale pattern |
| |
| Authors: | John E Gross Colleen Zank N Thompson Hobbs Donald E Spalinger |
| |
| Institution: | (1) Natural Resource Ecology Laboratory, Colorado State University, 80523 Ft. Collins, CO, USA;(2) Mammals Research Section, Colorado Division of Wildlife, 316 West Prospect, 80526 Ft. Collins, CO, USA;(3) Present address: Parkview 2122, POB 72478, Johannesburg, South Africa;(4) Texas Agricultural Experiment Station, Texas A&M University, 1619 Garner Field Road, 78801 Uvalde, TX, USA |
| |
| Abstract: | Foraging herbivores respond to the spatial pattern of resources at a variety of scales. At small scales of space and time, existing models capture the essence of the feeding process and successfully predict intake rates. Models that operate over larger scales have not exhibited a similar success, in part because we have a limited understanding of the rules used by animals to make decisions in spatially complex environments, or of the consequences of departing from these rules. To evaluate the rules that large herbivores use when navigating between forages, we examined movements of bighorn sheep foraging on apparent prey (alfalfa plants) in hand-constructed patches of plants. Observations of movements and path lengths were compared to simulations that used a variety of different rules-of-thumb to determine a search path. Rules used in simulations ranged from a random walk with various detection distances, to more complicated rules that solved a variant of the travelling salesman problem. Simulations of a random walk yielded movement lengths that exceeded observations by a factor of 3 for long detection distances, and by 30-fold for short detection distances. Observed move distances were most closely approximated by simulations based on a nearest-neighbor ruleover 75 % of all moves by bighorn sheep were to the closest available plant. Movement rules based on random walks are clearly inappropriate for many herbivores that typically consume visually apparent plants, and we suggest the use of a nearest-neighbor rule for modelling foraging by large herbivores. |
| |
| Keywords: | foraging random walk spatial heterogeneity search rule |
| 本文献已被 SpringerLink 等数据库收录！ |
|
