This study examined how songbirds respond to the presence of a predator near their food source. The researcher placed a fake owl near a bird feeder in a forest and recorded the number of visits and duration of visits by songbirds both with and without the owl present. The location within the forest did not influence the birds' behavior. However, the presence of the owl significantly decreased the amount of time songbirds spent at the feeder, supporting the hypothesis that predators increase avoidance behaviors in songbirds. This avoidance could decrease the birds' ability to forage and negatively impact their fitness.

1. Appearance of a Predator Increases the
Avoidance Exhibited by Songbirds
Alexis Ernst and Dr. Pollina
INTRODUCTION
ABSTRACT
RESULTS
Because there was not a significant difference between Site A and Site
B (Figure 1), the data was pooled. There was not a significant difference
between the number of times the songbirds visited the feeders at each
condition (Figure 2). There was a significant difference between the
duration of the visits both with and without the appearance of a predator,
t=-2.775, df=25.215, p-value=0.0103 (Figure 3).
with without
012345
Appearance of Predator
NumberofVisits
with without
020406080
Appearance of Predator
DurationofVisit(seconds)
Figure 2. Number of Visits, With and Without the Appearance of a Predator
Figure 3. Duration of Visits, With and Without the Appearance of a Predator
Because of habitat fragmentation, songbirds may suffer from a decrease in fitness if they
are unable to forage normally, due to an increased amount of predators in an area. The
goal of this experiment was to determine if songbirds exhibit an increased amount of
avoidance when a predator appears to be present. We hypothesized that the appearance
of a predator would increase the amount of avoidance exhibited by songbirds. A feeder
with a fake Great-Horned owl near it, and a control feeder without the owl, were
observed. The feeder was set up at two sites within Blackwell Forest Preserve. The
number of times a songbird visited the feeder, and the duration of each visit were
recorded. Location within the forest preserve did not influence the amount of avoidance
exhibited by the songbirds, but the appearance of a predator significantly influenced the
amount of time spent at the feeder. Songbird populations may be at risk if they are forced
to live in areas with high concentrations of predators because they cannot forage
normally.
DISCUSSION
• Evidence suggests that the non-lethal effects of predation may impact bird populations
more than the lethal predation of birds, for example, the avoidance of foraging areas that
have high predation risks (Cresswell 2008).
• Landscape fragmentation may change predator-prey relationships by increasing the
number of predators or prey in a given area (Mortelliti et al., 2012).
• Some songbird species may be at increased risk when forced to forage in areas where
there is an increased number of predators.
• Because the presence of domestic cats increases in urban and suburban areas, where
feeders may be present, it will be important to understand how prey may react
(Bonnington et al., 2013).
• If songbirds have limited areas to forage naturally due to habitat fragmentation, more
species may become dependent on food sources such as bird feeders where there is
often a higher concentration of domestic cats and dogs.
• A past study examined the feeding behavior of Northwestern Crows and Glaucous-Winged
Gulls in the presence of domestic dogs (Dunbrack and Dunbrack, 2010). This study found
that there was an increase in interspecific and intraspecific competition between the birds
when the predator was present which increased avoidance and influenced the competitive
interactions between the birds (Dunbrack and Dunbrack, 2010).
• The goal of this study is to determine if songbirds exhibit an increased amount of
avoidance when a predator appears to be present.
• Avoidance may lead to a decrease in fitness for organism or a species. This study will
specifically examine how various songbird species respond to the appearance of a fake
Great Horned Owl that is placed near a bird feeder.
• This study would benefit our current understanding of predator-prey interactions because
it may provide insight to the foraging behaviors of song birds when forced to be in an area
with an increased amount of predators.
• I have hypothesized that there will be an increase in the amount of avoidance exhibited
when the predator appears to be present when compared to the activity of birds when the
predator is not present.
Figure 1. Difference between the total duration of visits at both sites
within the forest preserve. There was not a significant difference,
p>>0.05.
• The significant difference between the duration of time spent at the
feeder by the songbirds allows us to support our hypothesis that the
songbirds would exhibit increased avoidance when a predator appears to
be present.
• Because the songbirds avoided staying at the feeder for an extended
period of time, our results may suggest that the appearance of predators
interfere with normal foraging behavior.
• Habitat fragmentation may force songbirds to forage in areas that have a
higher concentration of predators, including domestic cats. The increase
in predators may decrease a bird’s fitness, or a species’ population size.
FUTURE RESARCH
ACKNOWLEDGEMENTS
Blackwell Forest Preserve
Dr. Emily Pollina
Environmental Biology 416 Students
North Central College
LITERATURE CITED
• Bonnington, C., Gaston, K. J., Evans, K. L., and, Whittingham, M. 2013. Fearing the feline:
domestic cats reduce avian fecundity through trait-mediated indirect effects that
increase nest predation by other species. Journal Of Applied Ecology, 50:15-24.
• Cresswell, W. 2011. Predation in bird populations. Journal Of Ornithology. 152:251-263
• Dunbrack, T. E., & Dunbrack, R. L. 2010. Why take your dog on a picnic: presence of a potential
predator (Canis llipus familiaris) reverses the outcome of food competition between
Northwestern Crows (Corvus caurinus) and Glaucous-winged Gulls (Larus glaucescens).
Northwestern Naturalist, 91: 94-98
• Mortelliti, A., Sozio, G., Boccacci, F., Ranchelli, E., Cecere, J. G., Battisti, C., and, Boitani, L.
2012. Effect of habitat amount, configuration and quality in fragmented
landscapes. Acta Oecologica. 45:1-7
• Future research should focus on the avoidance exhibited
by songbirds in both fragmented forests and suburban
communities (parks and backyards where songbirds
frequently forage).
• Because the birds often fled the feeder when the head of
the owl moved, future researchers may want to look at
the relationship between the owl movements and the
duration of the visits.
• It may be beneficial to examine how birds respond to
various types of predators, for example, a domestic cat or
dog, or a Coopers Hawk.
• A possible source of error in this experiment was that the
songbirds in the forest preserve may not have been used
to eating from a bird feeder. This may have impacted the
number of visits to the feeder.
• Future research should try to look for changes in natural foraging behavior
when a predator appears to be present.
• The observer in this experiment may have impacted the number of visits to
the feeder as well as the duration of the visits. Future research could
observe from various distances in order to insure the observer did not
interfere with the results.
Location: Blackwell Forest Preserve
Predator: Fake Great Horned Owl With Rotating Head
A bird feeder with wild bird seed was set up at each
site.
Site A Site B
4 Observations With the
Appearance of a Predator
4 Observations Without the
Appearance of a Predator (control)
Number of Visits and the Duration of Each Visit were
Recorded. Predator was placed no more than 3 feet
from feeder. Each observation was 1 hour long.
METHODS