Group Size and Foraging Behavior Brandi Norris, Brittani Sanford, and Charnele Johnson

What’s the Question?  Question: Is there any patterns of group size and foraging attempts made by vultures and crows. Also, is the amount of time the birds spent foraging and walking different for birds that were alone or in a group.  Prediction: We predict that the larger the group of birds in an area the less scans and more foraging attempts will be made.  Hypothesis: If group size increases, then the need to scan more often will decrease.

Background  Social Roosting  Seasonal Roosting  Locating Food  Predation  Vulture dominance order  Crows tolerant of other crows

What’s Being Tested?  Species: Black vulture (Coragyps atratus) and American Crow (Corvus brachyrhynchos)  Sampling: SELU vultures and crows  Results (Type of analysis): T-test

Materials  SELU Conservatory  Carcass cam

Procedures  Recording Walking Around, Scans, and Foraging Attempts  Observations took place in mornings and nights (Sunday to Sunday)  Alone or in groups  Group Size  Timer reset if bird came or left  New bird chosen after every observation  Visit

Results BehaviorAlone or Group?Mean ± SET values Degrees of freedom P value Walking Alone4.20 ± Group2.93 ± 0.32 Foraging Alone3.15 ± Group3.21 ± 0.25 Table 1. Table shows the significance in foraging and walking when a bird was alone as opposed to being in a group.

Results Figure 1. Graph shows the relationship between scans per minute versus whether or not the birds were alone or in groups.

Discussion  Table 1 described the relationship between walking and foraging for birds in groups minus birds that were walking around the carcass alone.  Not significant  Figure 1 measured the scans per minute between birds that were is groups versus birds that were alone.  Significant

What could be done better  longer duration of time  more accurate technology  more specific times throughout the day in which observers can watch for the birds.

Any Questions?

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