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An Analysis of The Differences I n The Frequency of Prey Items Caught by Maryland Owls

An Analysis of The Differences I n The Frequency of Prey Items Caught by Maryland Owls. A Research Proposal Matt Bostick. Background: Owls of Maryland. Five species of owls live in or pass through Maryland. Barn owls Great Horned owl Barred owls Eastern Screech owl Northern Saw-whet owl.

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An Analysis of The Differences I n The Frequency of Prey Items Caught by Maryland Owls

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  1. An Analysis of The Differences In The Frequency of Prey Items Caught by Maryland Owls A Research Proposal Matt Bostick

  2. Background: Owls of Maryland Five species of owls live in or pass through Maryland. • Barn owls • Great Horned owl • Barred owls • Eastern Screech owl • Northern Saw-whet owl Barred Owl

  3. Adaptations as predators • Owls have special adaptations that enable them to hunt at night. Large and fixed eyes with binocular vision and good depth perception. Owls have developed an incredibly flexible neck that allows them to turn their head 270 degrees in both directions. Their eyes are also extremely light sensitive, allowing them to see well at night. Barred Owl

  4. Owls as predators Owls rely on silent flight to surprise their prey. The shape of the owl’s flight feathers muffles the sound wind makes as it flows past them. Saw-Whet Owl

  5. An idealized food pyramid

  6. Owl Pellets – What Are They? • Owls do not have teeth for grinding and cannot pass whole bone and claws through their digestive tract safely. • The protein enzymes and strong acids that occur in the digestive tract of raptors do not digest the entire meal. • The relatively weak stomach muscles of the bird form the undigested fur, bones, feather etc. into a bolus (or wet slimy pellets). • The undigested portions may include beaks, claws, scales, or insect exoskeletons.

  7. Purpose: • To analyze the frequency of prey items caught by the 5 species of owls common to Maryland • To determine if the frequency of prey items is significantly different between the species observed.

  8. Owl Pellets • I examine owl 3 owl pellets from each species in order to estimate the frequency of prey items eaten.

  9. Species diversity has two components: • Species richness: how many different species are present in a habitat • Relative Frequency: total number of individuals of each species present given in % 1. Shrew 33% 2. Vole 18% 3. Mouse 17% 4. Squirrel 14% 5. Gopher 8% 6. Rat 6% 7. Bird 4%

  10. Hypothesis • I hypothesize that the frequency of prey items found in the owl pellets will be significantly different between species.

  11. Materials • I need: • 3 Owl Pellets from each species • Dissecting Pan • Forceps • Probe • Metric Ruler • Bone Identification Sheets • Gloves

  12. Methods- Bone Sorting Chart

  13. Chi-Square is a statistical test used to determine whether your experimentally observed results are consistent with your hypothesis.

  14. When using chi-square in biology, there is some vocabulary we must know: • Hypothesis = a proposed explanation of an observed phenomenon • Observed results= what you can observe during the course of an experiment • Expected results = what you expect to see based on your hypothesis (predictions)

  15. Our final formula: The formula includes: • X2= chi-square • (o - e) = observed minus expected [sometimes you may see this represented with a d which means the difference between the expected and observed results] • e = expected results • o = observed results and = sum of

  16. I will use a table to assist in my data organization.

  17. Chi – Square Critical Values

  18. Expected Results • I expect that the results from my chi-square analysis will indicate that significant differences in the frequency of prey items will exist between the 5 owl species studied.

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