effects of conspecific behavior and refuge complexity on anti-predator decision making author:...
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Effects of conspecific behavior and refuge complexity on anti-predator decision making
Author: Elizabeth TranMentor: Dr. Esteban Fernández-JuricicAffiliation: CSULB
Introduction Geographic range
Abundant bird often associated closely with human habitation.
Habitat Native western population occurs in a wide variety of
habitats ranging from undisturbed desert to chaparral and open coniferous forests to cities
Prefers edge habitat, and even in desert areas, these finches require a source of water, as well as structures for perching and nesting
Introduction
Why House Finches? Abundance Easy to handle Good model for predator-
prey interaction
Why a raptor? Good predator in the wild A convincing predator Natural predator of
House Finches along with cats and snakes
Introduction Current Understanding
Studies of lizards Thermal Cost Reaction to predator Repeated attacks Tradeoffs
Reaction of bird to Predator Before and after response
No studies have been performed that show prey reaction of birds in a refuge after an attack
Introduction What will I do?
Determine the scanning (duration and rate) intake rate feeding time handling time foraging efficiency recovery time searching time (duration and rate) time in refuge (3 levels) time in link moving rate in link moving rate in refuge
Hypothesis Focal animal with conspecific foraging will also
forage without scanning Flock with animal foraging will perceive that there is no predator
Focal animal with conspecific scanning will also scan while foraging
Scanning means that there are predators nearby
Focal animal in refuge with low foliage will return to foraging faster
Not enough cover has higher cost than staying in refuge
Introduction
Materials and methods Animal collection/sample size
House Finches will be caught by OCVC staff under its license
90 adult individuals from local populations (similar proportion of males and females)
Materials and methods Animal care
Feeding (water and sunflower seeds with variety of other seeds)
Placed in Animal Facilities with constant air temperature
Infection control Removal of bedding daily Animal that contain certain disease (West Nile
Virus) will be remove from the population
Materials and methods Treatments and general procedures
All House Finches are tagged Animals will be housed in groups and will
undergo the experimental conditions only once Experiment will be conducted during the non-
breeding season Food deprivation period
Materials and methods 2 manipulations
Conspecific behaviors 3 levels
control with no conspecifics, conspecifics foraging, conspecifics scanning
Foliage 2 levels
low high
Materials and methods Statistical analyses
Statistica Software
Factorial ANCOVA
To determine if there is a significant difference in refuge usage in each manipulation (social condition, cage condition, etc.)
Determine the recovery time for each manipulation
Expected results
Table 1. Variables recorded from each experiment. (Similar table to Creswell, Quinn, Whittingham, & Butler, 2003)(Standard variables are in bold and were in all initial models.)
type of variable variable
individual birds Individualsexbody condition (mass/wing length)
confounding variables trial numbera
days in captivitya
model flight speedtime of experimentfeeding time (hunger level)position of the House Finches in the experimental cage
vigilance variable head-up rateb
mean duration of head-up periodsb
proportion of time spent with head upb
scanning time
foraging variable mean duration of head-down (food searching) periodb
peck rateb
handling timeintake rateforaging efficiencyfeeding time
response variable time from first possible appearance of the model to response (transformed by log)response type (flight or freezing)recovering time
refuge variable time in refuge in three levels (low, middle, high)time in the linkmoving rate-linkmoving rate-refuge
Expected results
Figure 2. The speed of House Finches response to an approaching model sparrow hawk was dependent on the head-up rate. The graph illustrates residual transformed response time (controlling for position of the House Finches, model speed, trial number and body condition) with head-up rate. (Similar graph to Creswell, Quinn, Whittingham, & Butler, 2003)
Expected results
Figure 3. Head-up rate was dependent on the peck rate. Non-significant variables removed from the model were, sex, response type, trial number and body condition. (Similar graph to Creswell, Quinn, Whittingham, & Butler, 2003)
Expected results
Time spent in refuge
Refuge patch foliage
Low
High
Figure 4. The time House Finches spend in the refuge corresponded to the amount of foliage of the refuge depending on the attack condition of the predator and trade-off.
Conclusion
The predation risk forces the animals to use anti-predator behaviors having increased associated cost Increasing time spent in
the refuge Increase time spent
scanning
The emergence from refuge increases when the amount of food availability was high and when the predator’s attack was unsuccessful