Geoscience Reference
In-Depth Information
Table 5.1
Evaluation of Methods Used to Investigate Vertebrate Food Habits
Method
Advantages
Disadvantages
Direct observation
Inexpensive
Sample age or sex differences
Limited to diurnal periods and
open habits
if these can be determined
Presence of observer in the
field affects activity of
consumer and potential
prey
Lead animals
Provide very precise
information
Expensive
Limited sample size
Selection can be investigated
by sampling available
foods
Results considered artificial
unless subject acclimated
before data collection
Feeding site surveys
Food remains
Can provide summary of
major foods consumed
Small or completely consumed
foods are not surveyed
Can estimate biomass
consumed
Cannot examine age or sex
differences in food use
Before-after
comparisons
Can estimate biomass
consumed
Must be able to differentiate
consumers
Exclosures
Useful in evaluating long-
term effects of herbivory
on plant community
dynamics
Provides information only on
major plants consumed
No information on diets of
age or sex categories
Must be able to distinguish
foraging by sympatric
herbivores
Postingestion samples
Pellets or feces
Able to sample large segments
of population throughout
year
Cannot differentiate samples
by age or sex categories
Differential digestibility limits
Inexpensive
evaluation of importance of
various foods
Gastrointestinal
tracts
Able to examine age and sex
differences
Can examine other parameters
Samples usually limited to
legal harvest by hunters or
trappers
(e.g., physical condition
and reproductive rates)
from other carcass samples
