Predatory Birds

Advanced Zoology

Word count: (excl. references)

INTRODUCTION

When taken literally, the term ‘predatory birds’ or ‘birds of prey’ can have a wide range of meanings. Some meanings include any bird that hunts and kills to eat many organisms from insects to vertebrates (Burton, 1989). However, this report will be coupling this definition with the definition that birds that use their eyesight to seek out prey and use powerful beaks and talons to catch and kill prey. For this study, owls will be the main area of interest. This is significant as owls eat and digest in certain ways.

All owls are carnivorous predatory birds, which feed on both invertebrates and vertebrates (Craighead & Craighead, 1969). Owls use their good eyesight to seek out prey from high perches. The owl has very good eyes for this strategy as their large eyes coupled with a small skull has over time morphed the eyes to become tubular in shape (Pettigew & Konishi, 1973). This aids the owls mostly in nocturnal scenarios to seek out its prey. When the owl has its prey, the talons and the beak tear and crush the skull of the prey and knead the body (Konig, Weick, & Becking, 1999). When the prey is finally consumed, the food does not enter a crop, like most birds. This is because instead of a crop, an owl has a stomach of two parts. The first part is the proventriculus. This part produces everything necessary to start digestion of the food while the second part (the gizzard) has large and strong muscles that break up softer parts of the food while the hard parts (such as bone) are left behind. The left behind fragments are compressed into a pallet and eventually (passing back through the proventriculas) exit the owl via the beak (Smith & Richmond, 1972).

The existence of these pallets has given scientists the ability to analyze the contents of the pallets and determine the diets of owls. In addition to this, scientists can then see what food is/was available to the owls in...