DOCSLIB.ORG

Who Did the Owl Eat?

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Who Did the Owl Eat? WHO DID THE OWL EAT? Overview: Through the dissection of owl pellets, students will learn how owls fit into the salt marsh habitat, which animals live in the owls' habitat (by observing what animals the owls have eaten) and about the skeletal bones of the prey. Content Standards Correlations: Science, p. 292 Grades: K-6 SUPPORTING INFORMATION FOR THIS ACTIVITY Key Concepts: Owls have • Owls are found all over the world. The Barn Owl has 17 specific adaptations that subspecies located throughout the world. enable them to be superb • Owls range in size from 4 '/a inches (least pygmy) to 2 !/2 feet hunters. These adaptations (great grey). include: superb hearing, • An adaptation is a change in a living thing that helps it survive. eyesight, wings, and talons. • Owls have very unique adaptations that make them superb night By studying owl pellets we can hunters. Their facial disks aid hearing - the round area of feathers learn more about the animals that inhabit the salt marsh on the face directs sound to the ears. (Try cupping your hands habitat and about the salt around your ears - it's the same idea!) marsh food chain. • A Bam Owl can hear a mouse chewing grass seeds or moving around 40 feet away. Objectives: • One ear is higher on the head than the other so that the owl can Students will be able to: move their head around too find the exact location of their prey. • define several adaptations of • Since an owl's eyes are found on the front of the head (like owls • identify rodent and bird people) they have binocular vision. bones • Owls eyes are large in order to allow a lot of light to enter. Their • name one thing they can eyes are so big that they have no room to move up, down or learn about the salt marsh sideways. The owl must keep turning its head to follow a moving habitat by studying owl object. Owls have 14 bones in their neck so they can turn their pellets neck 180 degrees each direction. (An owl can turn its neck so far 'and so fast, it sometimes looks as though the head is spinning 360 Materials: degrees!) • Who Did the Owl Eat? Video checked out from the • The feathers on the owl's wing have soft edges that make their Refuge flight silent - another sign of a good hunter. • owl pellets (1 for every • Once the owl has located its prey, it swoops down and grabs it with student or 1 for every 2 its very sharp "claws" or talons. Owls have four talons at the ends students - provided by the of their feathered legs - two face forward and one backward, teachers) while the one the outside can face forward or backward, so they • newspaper or other can have opposing pairs of talons. Once an animal is in the owl's protective covering grasp, it rarely escapes. • quartered Petri dishes or other containers • They swallow their prey head first. • tweezers • The prey goes into the first stomach, a wide place in the • hand Lenses esophagus, where digestion is started. Later it moves down into a • food Web Poster p. 167 second stomach, called the gizzard. All of the meat is digested and • Bone identification chart passed through a tiny opening in the gut. The non-digestible items p. 168 (1 copy for every left in the second stomach are formed into a compact clump of student) bones and fur or feathers (shaped somewhat like egg) which is regurgitated by the owl. This is an owl pellet. Time: 50 minutes Post-Visit Classroom Activities- Birds and Migration Studies 163 • Indigestible animal parts found in pellets include: Ask mammal bones, beaks, claws and bones of birds; ? What is an owl pellet? (Take different bones of reptile and amphibians; hard portions of answers.) insects; and seed husks or other coarse vegetable materials from the stomachs of the prey. Read • Digestion requires 12 to 22 hours. "We are now going to watch video called Who Did • One meal may include a mouse and a bird or two the Owl Eat? to leam more about owls and their owl to three rodents. The marshes around the Don pellets." Edwards San Francisco Bay National Wildlife Refuge have five mouse-sized animals including: Do voles (Microtus califonicus), house mouse (Mus Show the 13 minute video Who Did the Owl Eat? musculus), white-footed deer mouse (Peromyscus maniculatus), salt marsh harvest mouse Ask (Reithrodontomys raviventris), and the wandering ? What do owls eat? (Small mammals and shrew (Sorex vagrans). The red-winged black occasionally small birds.) bird is another important prey item that is ? What is an owl pellet? (Undigested remains of commonly found in owl pellets. what an owl ate. It is the bones, fur and feathers • Owls help keep the rodent population in check. which the owl collects in its stomach and clumps up • Pellets are often associated with birds of prey, into an egg shaped owl pellet, which it then regurgi- however, 330 species of from more than 60 birds tates.) families produce pellets. These families include: ? What does adaptation mean? (A change in a robins, starling, king fishers and tree swallows as living thing that helps it survive.) well as owls, hawks and eagles. ? What types of adaptations would an owl need TEACHING METHOD to be able to hunt at night? (Take many different answers- improved hearing, eyesight, etc.) Preparing for the Activity Do ? Do you think owls are the only type of bird 3 weeks prior to conducting this activity check out the that regurgitates pellets? (No. Pellets are often Who Did the Owl Eat? Video from the Environmen- associated with birds of prey, however, 330 species of tal Education Staff at the Don Edwards San from more than 60 birds families produce pellets. Francisco Bay National Wildlife Refuge (510) 792- These families include: robins, starling, king fishers 0222. and tree swallows as well as owls, hawks and eagles.) Conducting the Activity Do Read Cover the students desks or work tables with "Scientists dissect owl pellets to look a the different newspaper or other protective covering. bones, fur, or feathers that are inside." Read Ask "Owls are found all around the world. They range in ? As scientists, what can we learn from owl size from 4 !/2 inches (least pygmy) to 2 Vi feet (great pellets? (A scientist might want to study owl pellets grey) long. There are a few different types of owls to learn how owls fit into the food web, to find what found throughout the San Francisco Bay including, animals live in the owls habitat, and to learn about the burrowing owls, short eared owls, and barn owls. skeletal bones of their prey.) Today, we are going to be studying owls by dissecting owl pellets." Read "Today we are going to become scientists to find out what species of animals these owls have eaten." 164 Post Visit Classroom Activities- Birds and Migration Studies Do premolars, unlike the deer mouse (above). Pull a Pass out the owl pellets (1 per student or 1 to a pair molar and note the roots on the tooth. of student), the quartered petri dishes or other containers, tweezers, and hand lenses. Salt marsh harvest mouse: You may never see one of • Have the students break the pellets apart by these (they hide very well and are not easily captured grasping each end and then slowly and gently by owls; in addition they are not found in owl pellets pulling the ends apart. from geographic areas outside of the San Francisco • Continue to pull mats of fur or feathers apart Bay), but if you do, remember that the upper incisors looking for skulls and bones. (Tweezers are (front teeth) are orange and have a vertical groove in available for removing stubborn fur.) each tooth. • The bones from each pellet can be separated by type in the quartered petri dish. Roof rat: These are larger than any of the rodents listed above. The teeth have roots, but not on the • Give each student a copy of the bone identification mount of sample skulls that the parietal bone in the chart on p. 168. Have the students place the rear part of the skull is shaped differently between bones in the appropriate places on the chart. the roof rat and Norwegian rat. Holding the skull • Circulate around to the students and help them facing away from you, note that the parietal of the identify the bones. Bones found in pellets can be roof is wider and more narrow, like the roof of a from rodents, shrews, and birds. Note: The salt house. Whereas, the parietal of the Norwegian rat is marsh harvest mouse is found in the salt higher in relation to width. marshes of the San Francisco Bay, but will not seen in pellets that are ordered since they come Norwegian rat: See above. A parietal bone is wider from a different geographic location. If you than that of the Roof rat. This rat also has roots on have owl pellets from the San Francisco Bay the molars. Area they still probably will not be seen because this mouse stays under cover and can Gopher: The skull is much larger than that of the rat not ordinarily be caught by an owl. or mouse, with sturdy molars that have no roots. Identification of Some Common Prey Types Order Insectivora are small mammals that eat Order Rodentia consists of small to medium sized insects. These include shrews, moles, and bats. mammals, including squirrels, marmots, mice, and Below is a list of mammals from order Insectivora rats.
Load more

Recommended publications
  • Owl Pellet Dissection Activity
    Owl Pellet Dissection Activity: Background: Owl pellets are neat little packages of fur, bones, and other indigestible stuff that are regurgitated (spit up) sometime after an owl has finished digesting several meals. You can find owl pellets on the ground under trees where owls like to roost or nest. All owls cough up pellets as a part of how they digest their food. Most of the time, they swallow their prey whole without chewing or tearing the flesh apart. This means that owls naturally have a lot more bones, feathers, and fur in their diet. Owls can digest only the soft muscles and organs of their prey. The bones, teeth, fur, feathers, scales, or insect skeletons are too dense and cannot be converted into energy. The harder parts may also puncture an owl’s soft, curved intestines if passed through its digestive tract. Instead, the waste material is formed into a pellet in the gizzard, a muscular pouch in the owl’s digestive system. The gizzard operates like a trash compactor, pressing all the bones, fur, feathers, or other indigestible stuff into a firm, oval-shaped ball. When the pellet gets big enough, it is passed back up the esophagus to be cast out (thrown up) about twelve hours after eating. Although other birds, like eagles and hawks, also regurgitate pellets, owls are more efficient at it and they regurgitate more frequently. Owls swallow their prey whole, ingesting the entire skeleton. Other raptors selectively tear at their prey, eating only the soft digestible parts and leaving the indigestible bones. Also, unlike other birds, owls do not have a crop, which is an organ that holds food until the stomach is ready to receive it.
    [Show full text]
  • Additional Specimen of Microraptor Provides Unique Evidence of Dinosaurs Preying on Birds
    Additional specimen of Microraptor provides unique evidence of dinosaurs preying on birds Jingmai O’Connor1, Zhonghe Zhou1, and Xing Xu Key Laboratory of Evolutionary Systematics of Vertebrates, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing 100044, China Contributed by Zhonghe Zhou, October 28, 2011 (sent for review September 13, 2011) Preserved indicators of diet are extremely rare in the fossil record; The vertebral column of this specimen is complete except for even more so is unequivocal direct evidence for predator–prey its proximal and distal ends; pleurocoels are absent from the relationships. Here, we report on a unique specimen of the small thoracic vertebrae, as in dromaeosaurids and basal birds. Poor nonavian theropod Microraptor gui from the Early Cretaceous preservation prevents clear observation of sutures; however, Jehol biota, China, which has the remains of an adult enantiorni- there does not appear to be any separation between the neural thine bird preserved in its abdomen, most likely not scavenged, arches and vertebral centra, or any other indicators that the but captured and consumed by the dinosaur. We provide direct specimen is a juvenile. The number of caudal vertebrae cannot evidence for the dietary preferences of Microraptor and a nonavian be estimated, but the elongate distal caudals are tightly bounded dinosaur feeding on a bird. Further, because Jehol enantiorni- by elongated zygapophyses, as in other dromaeosaurids. The rib thines were distinctly arboreal, in contrast to their cursorial orni- cage is nearly completely preserved; both right and left sides are thurine counterparts, this fossil suggests that Microraptor hunted visible ventrally closed by the articulated gastral basket.
    [Show full text]
  • Wildlife Center Classroom Series Owl Pellets: Little Packages of Owl Puke
    Wildlife Center Classroom Series Owl Pellets: Little Packages of Owl Puke Wednesday August 10, 2016 Raina Krasner, WCV: Hello, everyone! Welcome to today’s Wildlife Center Classroom Series! Raina Krasner, WCV: Today, we’re talking about something that I think many of you are familiar with – owl pellets! Otherwise known as owl puke, little furball gifts, tiny packages of bones. But let me stop myself before I give away too much of the good stuff. Comment From caleb (͡๏̯͡๏) WOO HOO! Kids think this may be one of the BEST Classroom Series EVER ~~ we LOVE to dissect Papa G'Ho pellets! Comment From Dave in Missouri Oh, oel puke, this will go good with my lunch!:) Raina Krasner, WCV: :) Raina Krasner, WCV: First, what is an owl pellet? Eagle Owl Pellet in Germany, Martin Lindner Wildlife Center Classroom Series: Owl Pellets: Little Packages of Owl Puke Page 1 Raina Krasner, WCV: When an owl eats its prey, it consumes most, if not all, parts of the animal. Raina Krasner, WCV: If you order a fast food hamburger (or a veggie burger!) and it comes to you in a neat little wax paper package, and on the hamburger there is lettuce, tomato, and pickles, you have the luxury of using your utensils or fingers to pull back the wax paper wrapper, and then pick apart the burger and pull off the parts you don’t like, don’t want, or can’t eat. Raina Krasner, WCV: An owl, however, has to eat everything – “wrapper”, toppings, and all. Raina Krasner, WCV: No handy little thumbs and fingers to pick apart the food.
    [Show full text]
  • For Creative Minds
    For Creative Minds The For Creative Minds educational section may be photocopied or printed from our website by the owner of this book for educational, non-commercial uses. Cross-curricular teaching activities, interactive quizzes, and more are available online. Go to ArbordalePublishing.com and click on the book’s cover to explore all the links. Biologist or Paleontologist? Scientists who study living things (biologists) often observe animals to learn about them. If they are working in the field, they might even see different animal signs (nests with eggs, footprints, or poop) that help them to better understand the animal they are studying. Scientists who study dinosaurs (paleontologists) learn about the animals by studying body or trace fossil clues. They sometimes use knowledge of today’s animals to help them understand the dinosaurs. Identify whether you think the following statements describe the work of a biologist or a paleontologist. Can you explain “why” to someone? 1. The scientist dissected the owl pellet to see what it had eaten. 2. The scientist discovered that the round-looking rock was fossilized poop (coprolite) containing bits of bone from a plant-eating dinosaur. 3. In 2011, scientists found several dinosaur feathers trapped in amber. 4. In 2007, scientists found a duckbilled dinosaur that was so well preserved that even the skin had fossilized. 5. Scientists watched the birds care for their young. 6. Scientists found fossils of an animal sitting on eggs in a nest in Mongolia. 7. Scientists used medical scanners to see inside fossils of a dino skull. Inside the crest were hollow passages similar to the inside of a horn.
    [Show full text]
  • P0549-P0553.Pdf
    SHORT COMMUNICATIONS 549 The Condor 99549-553 0 The Cooper Omithologlcal Society 1997 COMPARISON OF PELLETS VERSUS COLLECTED BIRDS FOR SAMPLING DIETS OF DOUBLE-CRESTED CORMORANTS CLAYTONE. DERBY AND JAMES R. LOVVORN~ Department of Zoology and Physiology, University of Wyoming, Laramie, WY 82071 Abstract. For many fish-eating birds, two types of sample sizes of colonial diving birds in given months samplescan be usedto determine diets of adultsduring or years are usually < 25 and often < 10 (e.g., Baltz both breeding and nonbreedingperiods: esophagus and and Morejohn 1977, Kennedy and Greer 1988, Otten- gizzard contentsof birds collected at feeding sites,and bather et al. 1994), althoughgreater samples are some- pellets (indigestible residue) cast up at roostsor breed- times possibleat wintering concentrations(Glahn et al. ing colonies. We compared these two methods for 1995). Collecting birds also requiresthat all important Double-crested Cormorants (Phalucrocorux auritus) feeding sites be located and sampled. collected on the North Platte River, Wyoming and Gathering pellets at colonies or roosts does not re- nesting at a nearby colony both before and after fin- quire killing birds, can provide integrative samplesof gerling trout were stockedin the river. Before stocking, all feeding sites, and can result in larger sample sizes there were no significant differences between pellets with less time and effort (Veldkamp 1995, Warke and and collected birds in percent massesof different fish Day 1995). However, this method cannot be used if types in different length classes. After stocking, the colonies or roosts are inaccessible(e.g., on cliffs), are two methodsyielded similar resultsfor different length directly over water where pellets cannot be retrieved classes,but differed in relative proportionsof suckers (on pilings, etc.), or have too few birds to yield enough and trout.
    [Show full text]
  • A Curious Pellet from a Great Horned Owl (Bubo Virginianus)
    University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln USGS Staff -- Published Research US Geological Survey 2005 A Curious Pellet From a Great Horned Owl (Bubo Virginianus) Neal Woodman USGS Patuxent Wildlife Research Center, [email protected] Carla J. Dove National Museum of Natural History, [email protected] Suzanne C. Peurach USGS Patuxent Wildlife Research Center, [email protected] Follow this and additional works at: https://digitalcommons.unl.edu/usgsstaffpub Woodman, Neal; Dove, Carla J.; and Peurach, Suzanne C., "A Curious Pellet From a Great Horned Owl (Bubo Virginianus)" (2005). USGS Staff -- Published Research. 619. https://digitalcommons.unl.edu/usgsstaffpub/619 This Article is brought to you for free and open access by the US Geological Survey at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in USGS Staff -- Published Research by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. 2005NORTHEASTERN NATURALIST 12(2):127–132 A Curious Pellet From a Great Horned Owl (Bubo Virginianus) 1, 2 1 NEAL WOODMAN *, CARLA J. DOVE , AND SUZANNE C. PEURACH Abstract – One of the traditional methods of determining the dietary preferences of owls relies upon the identification of bony remains of prey contained in regur- gitated pellets. Discovery of a pellet containing a large, complete primary feather from an adult, male Ring-necked Pheasant (Phasianus colchicus) prompted us to examine in detail a small sample of pellets from a Great Horned Owl (Bubo virginianus). Our analyses of feather and hair remains in these pellets docu- mented the presence of three species of birds and two species of mammals, whereas bones in the pellets represented only mammals.
    [Show full text]
  • Owl Pellet Project Review
    Owl Pellet Project Review: What have we learned about barn owls so far? Use this slideshow to quiz yourself. Write down the answers in your Journal in complete sentences that restate the questions, then check the next slide to see if you are correct. If you are incorrect, be sure to fix your answer! Owls are a type of carnivorous bird that is sometimes called a “bird of prey.” Q1. What term did we learn that means bird of prey? A1. A bird of prey is called a raptor. Q2. What are some other raptors besides owls? This is my friend Megan with an Eagle Owl. She works at the Cincinnati Zoo. Other raptors are eagles, hawks, ospreys, and falcons. Red-tailed Hawk Bald Eagle Falcons Osprey This Secretary Bird is also a raptor. I saw some of these crazy-looking birds in Namibia. Although they can fly very well, they usually hunt on the ground. These guys even kill and eat snakes! Q3. Are all carnivorous birds raptors? Support your answer with evidence! Pelicans eat fish. So do Penguins! FACTS: 1. A carnivorous animal eats other animals. 2. A raptor has sharp talons with which to catch its prey and a sharp beak for tearing it up. A3. Possible answer: Raptors are carnivorous birds of prey with sharp, hooked beaks and talons. There are some carnivorous birds which are not raptors. For example, penguins and pelicans eat fish, which are animals, but they do not possess sharp talons or beaks specialized for tearing. Make sure the question is restated and that you provided supporting evidence! An adaptation is a physical or behavioral trait which helps and organism survive in its environment.
    [Show full text]
  • AN ANALYSIS of BIRD PELLETS FOUND on LUNDY by ALAN ROWLAND Mole Cottage, Chapel Close, Woodford, Morwenstow, Cornwall, EX23 9JR E-Mail: [email protected]
    Journal of the Lundy Field Society, 4, 2014 AN ANALYSIS OF BIRD PELLETS FOUND ON LUNDY by ALAN ROWLAND Mole Cottage, Chapel Close, Woodford, Morwenstow, Cornwall, EX23 9JR e-mail: [email protected] ABSTRACT Bird pellets are a potential source of information on food preferences and composition of local fauna. Sixteen pellets from three different bird taxa (raptors, gulls, corvids) were collected from Lundy over a period of two years and the contents subsequently analysed to identify prey and predator. Keywords: Lundy, bird pellets, raptors, gulls, corvids INTRODUCTION Owl pellets, especially those of owls such as Barn Owl (Tyto alba), are a useful source of identifying mammal distribution as well as predation statistics. Owls swallow their prey whole and eject the indigestible remains. These remains can be teased apart to reveal the bird’s choice of diet as well as the composition of the local small mammal, bird and invertebrate population. Some species, like Barn Owl, have preferred perches where they regularly return to digest their food. These perches are often inside barns or other buildings, or within sheltered areas, so the ejected pellets can be easily found and suffer minimal damage from wind and rain. Such devotion to a perch means that pellets can usually be identified to species with some degree of certainty (RSPB, undated). The pellets of species other than owls are occasionally described. Witherby et al., 1963, gives pellet sizes of Peregrines to be 40-45mm in length by 22-25mm in diameter though they can be much smaller and often taper at one end; Kestrel pellets are typically 30-35mm in length by 9-15mm in diameter and Sparrowhawk pellets 21-40mm long by 10-12mm in diameter.
    [Show full text]
  • Pellet Egestion in Modern Carnivorous Snakes
    Current Zoology, 2020, 66(5), 593–595 doi: 10.1093/cz/zoaa009 Advance Access Publication Date: 7 March 2020 Letter to the Editor Letter to the Editor Pellet egestion in modern carnivorous snakes a,b, c Stanisław BURY * and Agnieszka DROHOBYCKA-WAWRYKA aInstitute of Environmental Sciences, Jagiellonian University, Gronostajowa 7, Krako´w, 30-387, Poland, bNATRIX Herpetological Association, Legnicka 65, Wrocław, 54-206, Poland and cMedicavet Veterinary Clinic, Kapelanka Downloaded from https://academic.oup.com/cz/article/66/5/593/5799074 by guest on 01 October 2021 13c, Krako´w, 30-347, Poland *Address correspondence to Stanisław Bury. E-mail: [email protected]. Handling editor: Xiang Ji Received on 7 January 2020; accepted on 2 March 2020 Food resources vary in terms of digestibility and constraints in food mass: 23.4 g), 7 days after ingestion of a vole, prior next feeding, a processing are an essential factor driving the evolution of adapta- compact mass of distinguishable shape was palpated. The location tions to cope with them, for example, a complex morphology of of the object in the mid-body at approximately half of the snout– gastric tract, symbiosis with microorganisms, enzymatic specializa- vent length indicated its location in the stomach, which was further tion (McNab 2002). Pellet egestion is another important adaptation confirmed by the X-ray examination (performed in MedicaVet that enables to remove indigestible food particles and is observed in Veterinary Clinic, Cracow, Poland; Figure 1A). One day later the several vertebrate taxa. Pellets are most commonly reported in sau- specimen was observed to eject orally a structure resembling avian ropsids, particularly birds, but published records indicate pellet for- pellet, that is, containing bones and fur, being dry and lacking any mation also in the 2nd groups of sauropsids, that is, nonavian soft tissues (Figure 1B).
    [Show full text]
  • Discovering Owl Pellets
    Discovering Owl Pellets Essential Question: Location: Indoors Do all animals digest their food in the same way? Objectives: Learners will At a Glance: 1) dissect an owl pellet and Learners will dissect an owl pellet and interpret clues to owl interpret clues to owl eating and digestion habits. eating and digestion habits. Next they will identify small 2) identify small mammal skulls mammal skulls and bones using a bone identification chart. and bones using a bone identification chart. Background: More than 300 species of birds in several different orders are Skills: communication, observation, data collection, known to regurgitate pellets of indigestible material listening, analysis including all owl species. Owl pellets are very useful in understanding owls’ feeding habits. Supplies: owl pellets (easy to locate Owls, like other birds, cannot chew their food. Small sources on internet) dissecting tools (toothpicks, prey is swallowed whole, skull intact. Larger prey, like a tweezers) skunk eaten by a Great Horned owl, may be torn into smaller paper plates pieces before being eaten. owl pellet bone ID sheet Discovering Owl Pellets Unlike most other birds, owls have no crop, and the Worksheet food passes straight into the foregut (they do not possess a Pencils gloves true stomach). The acid in the owls gut is rather weak with a pH of 2.2 - 2.5 which is the same as vinegar. This compares Subjects: science to diurnal birds of prey which have a pH of 1.3 - 1.8, which is approaching the pH of concentrated hydrochloric acid. Time: 40 minutes This means that only the soft tissues are digested; the bones and even fur and feathers remain virtually intact.
    [Show full text]
  • Diet Composition of Common Ravens Across the Urban-Wildland Interface of the West Mojave Desert
    Diet 244 RAVEN DIET AND URBANIZATION Diet composition of common ravens across the urban-wildland interface of the West Mojave Desert William B. Kristan III, William I. Boarman, and John J. Crayon Abstract Common ravens (Corvus corax) are human-subsidized scavengers and predators in the Mojave Desert. They have increased dramatically in number and have been implicated as contributors to the decline in desert tortoise (Gopherus agassizii) populations. Known patterns of increased fledging success near human developments suggested that food was the most likely resource subsidy received by ravens. Because ravens are opportunistic foragers with a generalist diet, we predicted that the types of resource subsidy provided by different kinds of human developments should be reflected in measures of diet com- position of breeding ravens. We estimated diet composition from contents of raven pel- lets collected at nests and related diet composition to distance of the nests from roads and point sources of resource subsidies, such as towns or landfills. Ravens that nested close to point subsidies far from major roads had the greatest incidence of trash in their diets. Ravens that nested close to roads but far from point subsidies had a low incidence of trash and a higher incidence of presumably road-killed mammals and reptiles. Ravens far from both roads and point subsidies had more plant material and arthropods, and ravens close to both roads and point subsidies had more birds and amphibians. Diet diversity was not related to distance from roads or developments. Fledging success was correlated with diet composition, such that birds with diets consistent with trash or road-kill subsidies fledged the greatest number of chicks.
    [Show full text]
  • Pedagogical Guide: the Raptor Pellet
    PEDAGOGICAL GUIDE: THE RAPTOR PELLET PEDAGOGICAL GUIDE : The Raptor Pellet TABLE OF CONTENTS PELLET PRELUDE Introduction…………......……………………………….............2 Formation of the raptor pellet….......…..............................….2 Pellet analysis ……………………….......…...............…....…..3 Amazing pellets!…………………………......……................…3 THE PELLET DISSECTION ACTIVITY Preparation.........………………………………………..…........4 List of materials......................................................................4 Dissection Instruction Sheet...................................................5 Activity wrap-up…………………………………….….....…...…6 SCIENTIFIC METHOD OPTION The Scientific Method....……............................................…..6 Scientific Report Worksheet...................................................7 Appendix I: THE BIRD DIGESTIVE SYSTEM..........……………..8 Appendix II: REFERENCE BOOKS......………..……………...…..9 © All rights reserved –Falcon Environmental Services, inc. 1 www.falcon.bz PEDAGOGICAL GUIDE : The Raptor Pellet PELLET PRELUDE INTRODUCTION Birds of prey are carnivorous birds that possess 3 important adaptations for hunting. They have an excellent vision which allows them to see prey a great distance away. They have powerful feet called talons which they use to catch the prey, and they have a hooked beak to break their prey’s neck and tear off meat. FORMATION OF THE RAPTOR PELLET Most raptors eat their entire prey. Some owls even eat them whole, in one gulp, when they are small enough of course! The bird’s stomach can digest the meat, the fat and other tissues but not the feathers, fur or bones of the prey. All these non-digested parts create a pellet in the bird’s gizzard, an organ of the digestive system. The process of digestion and of forming a pellet can take between 6 and 24 hours depending on the type and the size of the prey eaten. It is important the bird coughs up this mass of non- digested parts because it could get in the way of the absorption of nutrients and cause certain health problems.
    [Show full text]