Using Owl Pellets to Illustrate Energy Transfer from Prey to Predator

Using Owl Pellets to Illustrate Energy Transfer from Prey to Predator
Barn Owl Pellet Survey Using Owl Pellets to Illustrate Energy Transfer from Prey to Predator Webs of Life: Food Webs and Trophic Cascades February 19, 2011

Food Chains Versus Food Webs
Barn Owl pellets have often been used to teach/illustrate the concept of Food Chains and Food Webs in particular habitats. FOOD CHAINS FOLLOW A SINGLE PATH AS ANIMALS EAT EACH OTHER. Food chains Food chains shows what eats what in a particular habitat. A food chain shows what eats what in a particular habitat. For example, grass seed is eaten by a vole, which is eaten by a barn owl. The arrows between each item in the chain always point in the direction of energy flow - in other words, from the food to the feeder. The Sun is the ultimate source of energy for most communities of living things. Green plants absorb some of the Sun’s light energy to make their own food by photosynthesis. The other organisms in a food chain are consumers, because they all get their energy and biomass by consuming - eating - other organisms. It helps if you can recall the meaning of some common words used with food chains. FOOD WEBS SHOW HOW PLANTS & ANIMALS ARE INTERCONNECTED BY DIFFERENT PATHS. Energy transfer Energy is transferred along food chains from one stage to the next. But not all of the energy available to organisms at one stage can be absorbed by organisms at the next one. The amount of available energy decreases from one stage to the next. Some of the available energy goes into growth and the production of offspring. This energy becomes available to the next stage, but most of the available energy is used up in other ways: energy released by respiration is used for movement and other life processes, and is eventually lost as heat to the surroundings energy is lost in waste materials, such as faeces All of the energy used in these ways returns to the environment, and is not available to the next stage. The animation shows how the level of available energy goes down as it is transferred through a temperate forest food chain. Food Chain One path of energy flow Food Web Multiple pathways and everything is connected

Biomass Barn Owl A generalization exists among ecologists that on average, about 10% of the energy available in one trophic level will be passed on to the next; this is primarily due to the 3 reasons given above. Therefore, it is also reasonable to assume that in terms of biomass, each trophic level will weigh only about 10% of the level below it, and 10x as much as the level above it. It also seems, however, that every time I go to measure, test, or model this assumption I run into an inconsistency, so take this generalization with a big grain of salt. Still, it comes in useful In terms of human diet and feeding the world's population, consider this. If we all ate corn, there would be enough food for 10x as many of us as compared to a world where we all eat beef (or chicken, fish, pork, etc.). Another way of looking at it is this. Every time you eat meat, you are taking food out of the mouths of 9 other people, who could be fed with the plant material that was fed to the animal you are eating. Of course, it's not quite that simple, but you get the general idea. Pyramids of biomass Biomass means the mass of living material at a stage in a food chain. The biomass goes down as you go from one stage to the next, just like the amount of energy. The concept of biomass is important. It is a general principle that the further removed a trophic level is from its source (detritus or producer), the less biomass it will contain (biomass here would refer to the combined weight of all the organisms in the trophic level). This reduction in biomass occurs for several reasons: 1. not everything in the lower levels gets eaten 2. not everything that is eaten is digested 3. energy is always being lost as heat

Dissect barn owl pellets
Traditional Barn Owl Pellet Activity Part 1: Energy Flow and Food Webs in Ecosystems Objectives: Dissect barn owl pellets Use “Key to Skulls” to identify animal skulls found in pellets Use classroom findings to determine the average number of prey items per pellet Estimate the food mass that the owl consumed Procedure Work in pairs or small teams and set up your workstation with paper towels, toothpicks, probes, tweezers, ruler, magnifying glass and an owl pellet. 2. Before dissecting your pellet record the length, width (at its widest point) and remove the foil wrapping before weighing your owl pellet.

Barn Owls Ecologists study living organisms and their relationship to their environment. In a biotic community the existence of each population is influenced by the presence of all the other organisms. This association has an effect in both directions of the food chain or web. In this exercise we will use the Barn owl as a representative organism to learn more about energy flow and food webs in an ecosystem.

Barn Owls Barn owls (Tyto alba) along with hawks and eagles belong to a group of birds known as “raptors” or birds of prey. To minimize interspecies competition each of these birds are uniquely adapted to hunt in different habitats, different prey, at different times of day.

Barn Owl Description Golden-rust color with black flecks and a white facial disk Forward oriented eyes, large hooked beak, long hooked talons 31-39 cm (12-15 inches) long from head to tail g ( pounds) Adults are monogamous for life 44 inch wing span

Barn Owl Habitat Range: Found throughout most of the world. Absent primarily in regions with long dry or cold seasons Open country (pastures, prairies and grasslands, brush, swamps and forests) Large open regions which support an abundance of small rodents (such as agricultural regions in northwestern and southeastern U.S.) Often found in man-made structures (barns, church steeples) forest Distribution of Tyto alba one of the most wide-spread of all land birds swampland grassland

Barn Owl Hunting and Diet
Nocturnal hunters Complete carnivores – prey varies with on the owl’s habitat but includes insects, frogs, snakes, mammals (most often voles, pocket gophers) and birds Often swallow its prey whole Flesh and soft parts are digested and passed to the intestines for absorption Non-digestible parts (bones, teeth, fur, feathers and chitin from insects) are compressed into a pellet and regurgitated

Barn Owl Reproduction Barn Owls do not build a straw nest. Instead the regurgitated pellets get trampled into a pile in which eggs are deposited. 1-13 eggs, eggs are laid at two day intervals. Only females incubate eggs. Incubation starts with the first egg and lasts days. Hatching: occurs at 2-day intervals. Nestlings are featherless and blind, requiring the mother to feed them.

Barn Owl Pellets By examining the contents of the black pellets we can gain information about the owl’s seasonal and regional diet and habitat differences. The pellets can also effectively illustrate the nature of the food chain in which the owl is a predator. learn more about energy flow and food webs in an ecosystem.

Owl Pellet Survey Energy Transfer from Prey to Predator http://www
The National Owl Pellet Survey Report Analyses owl pellet batches from throughout the UK and records the results on a computer database. The data are then used to support the objectives of the survey and other research The vast majority of the pellets are from the Barn Owl (Tyto alba)

Owl Pellet Survey Energy Transfer from Prey to Predator
Materials and Methods Ordered from a number of educational resources (e.g., Wards, Genesis Inc.) Comparison groups from Northwestern and Southeastern US. Introduction Trophic levels describe the feeding relationships within a community. Energy pyramids are used to represent important aspects of trophic level interactions In this exercise we will examine the contents of barn owl (Tyto alba) pellets to learn more about food webs and energy flow in an ecosystem. Owl pellets can either be collected below owl roosting spots, (often found in barns, church steeples) in agricultural regions in the northwestern and southeastern U.S., or ordered from a number of educational resources (e.g., Wards, Genesis Inc.). Several batches of average sized pellets were dissolved in a solution of sodium hydroxide (NaOH) to separate the skeletal material from the pellet matrix. See “A new method of preparing owl pellets: Boiling NaOH,” at the end of this activity.

Part 1: Identification of Small Mammal Prey Items Visually sort skull and jaw bones to more easily identify the specimens Collections include pellets from Northwestern and Southeastern United States.

Helpful information: 3 main types of small mammalian prey: two types of rodents (voles and mice), and Insectivorous prey (almost all are shrews) are found in owl pellets. Details of the tooth and root patterns allow identification to species. Large differences are seen between the molar teeth, tooth and root patterns of the two rodent subfamilies. The teeth of shrews species have red tips. Using the keys, drawings, and photos provided, identify the skulls and jawbones.

Arranges specimens as seen in the figure below (skull, left and right jaw) for each prey type.

Part 2: Results by Number of Prey Items Once identification has been made, record the number of each prey type found (based on the number of skulls or paired jaw bones) on the Table 1A and/or Table 1B. Determine the Percent of Diet (i.e., availability of the prey species to the owl) by dividing the number or prey Frequency Found (n1) for each species by the Total number of prey found. Record your values on the column labeled Percent of Diet on the appropriate tables.

Mean Mass (g) Conversion Factor (b) Frequency Found (n1) Percent of Diet Biomass Units (n*b) = B1 Percent Biomass (B1/TB1) Vole 40 2 Mouse 20 1 Mole 55 2.75 Shrew 5 .25 Rat 240 12 Bird Gopher Site Northwest TOTALS 100% (TB1) Determine the Percent of Diet (i.e., availability of the prey species to the owl) divide the number or prey Frequency Found (n1) for each species by the Total number of prey found. Record you values in the column labeled Percent of Diet on the appropriate tables.

Part 3: Results by Food Value Determine the biomass that each prey represents in the diet of the barn owl. The importance of a given prey species to the owl diet depends not only on the relative number of individuals of the species consumed, but also on the typical body weight of the species. That is to say there is a difference between the “food value” (the energy) derived from a shrew (average mass 2 grams) as apposed to a vole (average mass 40 grams). Ecologists often want to quantify the relationships in a food web and determine, for example, how much each prey group contributes to the total intake of a top predator (e.g., Barn Owl). The importance of a given prey species to the owl diet depends not only on the relative number of individuals of the species consumed, but also on the typical body weight of the species. That is to say there is a difference between the “food value” (the energy) derived from a shrew (average mass 2 grams) as apposed to a vole (average mass 40 grams).

To determine how much each prey group contributes to the total intake of the owl food web… First - take the average mass of each prey groups and expressing it in terms of biomass of prey consumed. This calculation is done by taking the number of individuals in each prey group (n1) and multiplying it by the biomass conversion factor (b). The conversion factor is a standardized unit based on the assumption that a 20 gram mammal has a biomass conversion factor of 1.0. This number is the biomass. The percent biomass is calculated by dividing the biomass for each prey group (B1 or B2) by the total biomass (TB1 or TB2) respectively. Mean Mass (g) Conversion Factor (b) Frequency Found (n1) Percent of Diet Biomass Units (n*b) = B1 Percent Biomass (B1/TB1) Vole 40 2 Mouse 20 1 Mole 55 2.75 Shrew 5 .25 Rat 240 12 Bird Gopher Site Northwest TOTALS 100% (TB1)

Some Anatomy

Zygomatic Arch Infraorbital opening Auditory meatus Diestema Molarifomr teeth Zygomatic Arch

Birds Caprimulgus carolinensis (Chuck-will's-widow)
Kingdom: Animalia Phylum: Chordata Subphylum: Vertebrata Class: Aves Order: Caprimulgiformes Family: Caprimulgidae Genus: Caprimulgus Species: Caprimulgus carolinensis Geographic Range Chuck-will's-widows breed in suitable habitat throughout the southeastern United States, from Florida to Long Island, New York and west to Kansas, Oklahoma, and eastern Texas. They also breed in isolated areas of southern Ontario, northwestern Indiana along Lake Michigan, and in central and southern Ohio. They winter mainly in Central America from Tamaulipas, Mexico south to Colombia east of the Andes and in the Antilles Islands. They also winter in southern Florida and occasionally along the Gulf of Mexico in Texas, Louisiana, and Alabama. They have been reported in areas north of their breeding range as well, as far north as the Canadian maritime provinces and northern California. Habitat Elevation 2600 m (high) (8528 ft) Chuck-will's-widows are found in open woodlands, including deciduous, mixed, pine (Pinus), and oak-hickory (Quercus-Carya) forests. Openings and edges are important habitat features and these birds can be found in suburban areas with the appropriate characteristics. Where they co-occur with whippoorwills (Caprimulgus vociferus), Chuck-will's-widows are found in more open habitats. During migration and in winter they can be found in a wider variety of forested habitats and scrublands, including mixed agriculture areas. They have been found at elevations up to 2600 m in Colombia. Physical Description Mass 110 g (average) (3.87 oz) Length 28 to 32 cm (11.02 to 12.6 in) Chuck-will's-widows are larger than their well-known cousins, whip-poor-wills (Caprimulgus vociferus), but similar in overall appearance. They are the largest species of nightjar in North America. Chuck-will's-widows are cryptically colored in mottled, cinnamon-brown, cream, and black feathers that help to camouflage them when they roost during the day on tree branches or the ground. They are from 28 to 32 cm long, with wings from 20 to 22.5 cm long, and weighing approximately 110 g. Their tails are long, projecting beyond the wings when they are at rest, from 12.8 to 15.1 cm long. Males have white on the outer 3 tail feathers and a rufous with white collar on the throat. Females have a buffy collar on the throat and lack the white on their tail feathers. Males are also slightly larger than females. Immature individuals resemble females and there is no seasonal variation in plumage. No subspecies are recognized. Chuck-will's-widows are most often recognized by their voice, they are rarely seen. Chuck-will's-widows may hibernate like their western cousins, poorwills (Phalaenoptilus nuttallii), but this has yet to be confirmed. Food Habits Chuck-will's-widows eat nocturnal flying insects, especially beetles and moths, especially geometrid moths (Geometridae). They fly just above the ground, often along woodland edges, to capture insects in their large mouths. They may also forage over water or fly out to capture passing insects from perches. They forage mainly at dusk and dawn and when there is sufficient moonlight for low-light visual detection of flying insects. Chuck-will's-widows use their rictal bristles, the bristles around their mouths, to scoop up insects. They may also forage on the ground for insects or frogs, especially when they are molting, and they sometimes pursue and capture small birds, including palm warblers (Dendroica palmarum), yellow warblers (Dendroica petechia), worm-eating warblers (Helmitheros), hooded warblers (Wilsonia citrina), swamp sparrows (Melospiza georgiana), Carolina wrens (Thryothorus ludovicianus), Cuban emeralds (Chlorostilbon ricordii), common yellowthroats (Geothlypis trichas), and Cape May warblers (Dendroica tigrina). Chuck-will's-widows are often observed on roads where they collect rocks, presumably to help them grind and digest their insect prey. Ecosystem Roles Chuck-will's-widows are important predators of night-flying insects, filling a similar ecological role to large, insectivorous bats. Two species of louse flies are known to parasitize nests (Pseudolynchia brunnea and Pseudolynchia rufipes).

Birds Caprimulgus carolinensis (Chuck-will's-widow)

Shrew Kingdom: Animalia Phylum: Chordata Subphylum: Vertebrata
Class: Mammalia Order: Soricomorpha Family: Soricidae Geographic Range Northern short-tailed shrews are only native in the Nearctic region. They inhabit most of east central North America from southern Saskatchewan and Nova Scotia in Canada to central Nebraska and Georgia in the United States. Habitat Northern short-tailed shrews are found in nearly all terrestrial habitats. However, their populations are most dense in damp brushy woodlands, bushy bogs and marshes, and weedy and bushy borders of fields. These shrews are also common in cultivated fields, in flower and vegetable gardens, fence rows, and beside country roads. In the winter, they often retreat into barns, cellars and sheds. They need only sufficient vegetation to provide cover. They are slow to rehabit areas of forest burns. Northern short-tailed shrews construct elaborate runways under leaves, dirt, and snow and construct theirnests in tunnels or under logs and rocks. Food Habits Short-tailed shrews are voracious eaters and must feed frequently, commonly in the early and late afternoon. It is estimated that they consume and metabolize as much as three times their weight in food per day. The diet of Blarina brevicauda consists mainly of invertebrates, small vertebrates, and plant material. B. brevicauda stores food for winter, including snails and beetles, and in captivity puts nutmeats, sunflower seeds, and other edibles into storage. The submaxillary salivary glands of Blarina brevicauda produce a toxic material which is effective in subduing its prey. This enables it to prey upon animals much larger than itself, including salamanders, frogs, snakes, mice, birds, and other shrews. Blarina brevicauda (northern short-tailed shrew)

Northern short-tailed shrew Blarina brevicauda
What do the groups in Order Insectivora share • generally small • pentadactyl with plantigrade locomotion • rostrum tends to be long • pelage often consists only of guard hairs (modified in some forms as spines) • external pinnae are small or absent • small braincase with smooth cerebral hemispheres • auditory bullae are absent - instead there is a ringshaped tympanic bone. • testes usually abdominal, or if in scrotum, then anterior to penis (as in marsupials). • cloaca is present in some. • jugal is reduced or absent. • pubic symphysis is reduced.

Weasel Kingdom: Animalia Phylum: Chordata Subphylum: Vertebrata
Class: Mammalia Order: Carnivora Suborder: Caniformia Family: Mustelidae Diversity Mustelidae is the largest family within Carnivora and is comprised of 56 species in 22 genera. Members of this family include weasels, stoats, polecats, mink, marten, fishers, wolverines, otters, badgers and others. While many authors have traditionally considered skunks a subfamily within Mustelidae, recent molecular evidence indicates that skunks do not lie within the mustelid group and instead are recognized as a single family, Mephitidae, Habitat Mustelidae are distributed from the arctic to the tropics and occupy nearly all terrestrial habitats. Several species are semi- or nearly fully aquatic and inhabit freshwater rivers and streams, as well as coastal marine waters. Lifespan/Longevity Mustelids typically live between 5 and 20 years in the wild. (Nowak, 1991) Food Habits Mustelids are primarily carnivorous, but some species may at times eat plant material. A wide range of animal taxa are preyed upon by various members of this family; many mustelids are opportunistic feeders rather than specialists. However, many mustelids are especially adept at capturing small, mammalian prey. Weasels, for example, are capable of chasing and capturing rodents in their burrows. Otters are well-adapted to chasing and capturing aquatic prey, including fish, crustaceans, and other aquatic invertebrates. Mustelids hunt in a variety of terrestrial, aquatic, and arboreal habitats. Some species regularly prey on animals larger than themselves. Some species have been known to store food Mustela frenata (long-tailed weasel)

Long tailed weasel Mustela frenata

Moles Mole trails and tunnel entrances (such as these) can be a reliable way to track and identify moles. Kingdom: Animalia Phylum: Chordata Subphylum: Vertebrata Class: Mammalia Order: Soricomorpha Family: Talpidae Food Habits Scalopus aquaticus eats primarily earthworms. It also eats insects and their larvae, some vegetation, and, in captivity, ground beef, dog food, mice, and small birds. Each day this mole eats 25 to 100% of its own weight in food.

Moles Scalopus aquaticus (eastern mole)

Rabbits and Hares Kingdom: Animalia Phylum: Chordata
Subphylum: Vertebrata Class: Mammalia Order: Lagomorpha Family: Leporidae Sylviagus audubonii (Audubon’s cottontail) The family Leporidae consists of 11 genera and around 54 species, commonly known as hares and rabbits. Hares (genus Lepus) are generally larger than rabbits, have longer, black tipped ears and live solitary lives. Hares are born with open eyes, hair, and they can run within a few minutes of birth. Rabbits are born blind, naked, and remain in a fur-lined nest their first days of life. Most leporids are of medium size, from around 300 gm weight to domestic breeds that weigh 7 kg. They have thick, soft fur, and they range in color from white to dark brown. Northern species may undergo a seasonal molt from a summer brown pelage to a winter white. The ear pinnae of leporids are generally longer than wide. The limbs are long, and the hindlimbs are longer than forelimbs and in most are well adapted for running. Sylvilagus nuttallii (mountain conttontail Lepus americanus (snowshoe hare)

Rabbits and Hares Lepus americanus (snowshoe hare)
The skulls of leporids are unmistakeable. They are arched in profile and only slightly constricted between the orbits, very unlike their condition in related pikas. Supraorbital processes are present and consist of anterior and posterior processes. The rostrum is long and wide, and on its sides the maxillae are distinctively pitted. The squamosals and parietals may also be somewhat pitted. The zygomatic arch is broad; the jugal is short; and the bony part of the external auditory meatus is tubular and vertically directed. The dental formula is 2/1, 0/0, 3/2, 3/3 = 28 in most leporids. The first incisors are enlarged, and the second are small, peglike, and located immediately posterior to the first. The first incisors resemble those of rodents, except that they are completely encased by enamel. Canines are absent, and a large diastema separates incisors from cheekteeth. The cheekteeth appear relatively simple, with the occlusal surface being made up of two transverse ridges. The cheekteeth are strongly hypsodont in most species.

Rabbits and Hares Lepus americanus (snowshoe hare)

Pocket Gophers Family Geomyidae
Kingdom: Animalia Phylum: Chordata Subphylum: Vertebrata Class: Mammalia Order: Rodentia Suborder: Castorimorpha Family: Geomyidae The family Geomyidae includes 5 genera and around 35 species. They are found only in North and Central America. A number of groups of rodents have become fossorial (living most of their lives underground). The geomyids are one of them. Their bodies are strikingly modified for digging and living in burrows. They are stout without a distinct neck and with short, powerful legs. Their feet are broad and the toes are tipped with enlarged claws; the claws on the forefeet are especially well developed. Forefeet and hindfeet each have 5 digits, and the surface area of the forefeet is increased by the addition of a fringe of stiff hairs around the periphery. The tail is short, sparsely haired, and usually well supplied with nerves, muscles, and blood vessels. These animals move backwards almost as readily as forwards, and their tails probably provide important sensory information. Eyes and ears are small, but the eyes have enlarged lacrimal glands, presumably for providing fluid to wash out dirt. The lips can be closed behind the incisors, so that pocket gophers can use their incisors for loosening dirt or roots without filling their mouths with dirt. The name "pocket gopher" comes from the unusual fur-lined cheek pouches of these animals. These pouches, which extend from the side of the mouth well back onto the shoulders, are used for transporting food. They can be turned inside out. Most pocket gophers are moderately large, weighing a few hundred grams. A few species of Central American forms reach very large size, almost 1 kg. The pelage lacks underfur and is usually some shade of brown. It often closely matches the color of the soil in which the animal lives. The skulls of pocket gophers also reflect their fossorial habits. They are massively built, flattened in profile and angular in overall appearance. The zygomatic arches flare widely. At their anterior end is a large zygomatic plate and very small infraorbital canal, sunken into the skull and opening on the side of the rostrum; these animals are sciuromorphous. The temporal ridges are enlarged and help support large temporalis muscles; frequently, the ridges join in the middle of the skull to form a sagittal crest. On the ventral surface of the skull, there is a deep pit on each side of the rear of the palate. The incisive foramina are small and enclosed by the premaxillae, and the bullae are moderately large but not inflated. The lower jaws are sciurognathus. Pocket gophers have massive incisors. The dental formula is 1/1, 0/0, 1/1, 3/3 = 20. The premolars are large and 8-shaped (i.e., with deep indentations in the middle), and the molars are smaller and ring-shaped, sometimes with a posterior heel. All teeth are ever-growing. Geomyids are accomplished burrowers. Their burrow systems include both long, shallow tunnels used for foraging, and deep tunnels used for nesting, food storage, and as latrines. They dig by loosening the soil with their incisors and foreclaws, then pushing it with chest and forefeet to the surface or into empty burrows. The area of a burrow system is marked by numerous mounds where soil has been brought to the surface. During the winter, soil is packed into tunnels through the snow, and snowmelt leaves long "gopher cores" of earth lying on the surface. Pocket gophers usually close the mouths of their burrows, and opening a closed burrow will often bring the burrower hurrying to renew the plug. Pocket gophers feed primarily on roots and tubers, although they sometimes eat other parts of plants as well. Food is packed into the cheek pouches and carried to underground storage chambers. In some communities where gophers are abundant, they consume an amazing fraction of the underground productivity of plants. Pocket gophers are generally solitary and pugnacious, coming together only to reproduce. Their burrows, however, are used by a remarkable variety of other species of animals. The geologic record of this group extends to the early Miocene. They are almost certainly closely related to heteromyids. Pocket gophers tend to be found in small populations, probably due to the patchy distribution of appropriate soils. This, combined with their tendency to specialize to very local soil conditions in color, size, and other characteristics, has resulted in a large number of recognizable taxa (and some fascinating research on microevolutionary processes). Geomys breviceps (Braid’s pocket gopher)

Pocket Gopher Orthogeomys heterodus (variable pocket gopher)

Vole Microtus ochrogaster (prairie vole)
Kingdom: Animalia Phylum: Chordata Subphylum: Vertebrata Class: Mammalia Order: Rodentia Suborder: Myomorpha Family: Cricetidae Subfamily: Arvicolinae Genus: Microtus Species: Microtus ochrogaster Geographic Range Prairie voles, Microtus ochrogaster, occur from northeastern New Mexico to northern Alabama, western West Virginia, and northwest to central Alberta. (Stalling, 1990) Biogeographic Regions: nearctic (native ). Habitat Prairie voles are common in prairies, ungrazed pastures, fallow fields, weedy areas, road right-of-ways, and sometimes in soybean or alfalfa fields. If meadow voles occur in the same area, prairie voles occupy the areas with shorter, drier, and more varied vegetation. (Kurta, 1995; Stalling, 1990) Physical Description Mass 30 to 70 g; avg. 50 g (1.06 to 2.46 oz; avg oz) Length 125 to 180 mm; avg mm (4.92 to 7.09 in; avg. 6 in) Basal Metabolic Rate Microtus ochrogaster maintains uniform coloration throughout the year. It has dark brown to black hair tipped with black or brownish-yellow. This gives a grizzled effect to most of the pelage. The ventrum is light tan. The tail is bicolored. Occasionally, color variants with yellow, black, albino or spotted fur may be found. Prairie voles have five plantar tubercles on the hind feet and females have three pairs of mammary glands. The third lower molar has no closed triangles and three transverse loops. The third upper molar has two closed triangles. Adults have a total length of 125 to 180 mm, tail length of 25 to 45 mm, hind foot length of 17 to 23 mm, ear length of 10 to 15 mm, and weight between 30 and 70 grams. There is no significant sexual dimorphism in size or coloration. Food Habits Prairie voles are herbivorous. Food items include soft basal segments of grasses, tubers and roots, and seeds, which may be stored below ground. Insects are eaten when they are available. In winter, prairie voles sometimes eat the bark of woody vegetation. (Kurta, 1995) Predation Known predators hawks (Accipitridae) owls (Strigiformes) shrikes (Lanius) red foxes (Vulpes vulpes) coyotes (Canis latrans) bobcats (Lynx rufus) weasels (Mustela) snakes (Serpentes) Prairie voles use an extensive runway system comprized of grass tunnels that helps to hide them from predators. Prairie voles are preyed upon by a wide variety of small to medium-sized predators. They are important as a prey base for raptors, owls, snakes, weasels, foxes, and bobcats. Microtus is a greek word for "small ear" and ochrogaster is Greek for "yellow belly". Prairie voles undergo a two to four year population cycle where populations increase and decrease dramatically in that cycle.

Vole Microtus ochrogaster (prairie vole)

Vole Microtus pennsylvanicus (meadow vole)
Kingdom: Animalia Phylum: Chordata Subphylum: Vertebrata Class: Mammalia Order: Rodentia Suborder: Myomorpha Family: Cricetidae Subfamily: Arvicolinae Genus: Microtus Species: Microtus pennsylvanicus Geographic Range Microtus pennsylvanicus is the most widespread vole in North America. Its east to west range is continuous from central Alaska to the Atlantic coast. South of the Canadian border, its western limit is the Rocky mountains. The meadow vole is found as far south as New Mexico and Georgia (Maser and Storm 1970). Biogeographic Regions: nearctic (native ). Habitat Microtus pennsylvanicus can be found in mainly in meadows, lowland fields, grassy marshes, and along rivers and lakes. They are also occasionally found in flooded marshes, high grasslands near water, and orchards or open woodland if grassy (Jackson 1961). Physical Description Mass 33 to 65 g; avg g (1.16 to 2.29 oz; avg oz) Length 128 to 195 mm (5.04 to 7.68 in) Basal Metabolic Rate The total length of M. pennsylvanicus ranges from 128 to 195 mm with a tail about 40% of the body length. The dorsal surface is dark blackish brown to dark reddish brown with coarse black hairs. The ventral surface is grey or white and may be tinged with light brown. The winter pelage is duller and more grey. There is no sexual variation in size or color. The skull is moderately heavy, rather long, and slightly angular. The upper cheek tooth row is relatively long, about 7.2 mm, and the third premolar, usually a distinguishing characteristic among the voles, has an anterior complex, a posterior loop, and seven triangles in between, four lingual and three labial Food Habits Meadow voles feed mainly on the fresh grass, sedges, and herbs that are found locally within their range. They will also eat a variety of seeds and grains. From May until August they subsists on green and succulent vegetation. During the fall they switch to grains and seeds, and during the winter they have been known to feed on the bark and roots of shrubs and small trees. These voles will also eat tubers and bulbs when available. When this species overlaps the range of cranberries, meadow voles feed extensively on these fruits. They also eat other types of fruit. Meadow voles will eat flesh and are cannibalistic, especially on new born young. They do not show much storage behavior, but occasionally make small caches of tubers during the fall. Meadow voles are voracious eaters, consuming close to 60% of the body weight. When eating, these animals sit up and will stand to gnaw bark or a grain stalk Predation Known predators owls (Strigiformes) birds of prey (Falconiformes) snakes (Serpentes) red foxes (Vulpes vulpes) weasels (Mustela) Meadow voles are aggressive and will attack when cornered or captured. They take refuge from predators in their system of burrows and grass tunnels. Below is a list of some predators. If you see small openings in the grass that lead to mouse-sized tunnels both in the grass and into the ground, then you've found the home and foraging area of a vole.

Vole Microtus pennsylvanicus (meadow vole)

Mice Mus musculus (house mouse)
Kingdom: Animalia Phylum: Chordata Subphylum: Vertebrata Class: Mammalia Order: Rodentia Suborder: Myomorpha Family: Muridae Subfamily: Murinae Genus: Mus Species: Mus musculus Geographic Range Peromyscus keeni is found in western British Columbia, western Washington, and southeastern Alaska, including the Haida Gwaii (Queen Charlotte) islands, the Alexander Archipelago, and other coastal islands. Habitat Northwestern deer mice are adapted to many habitats, but appear to thrive in upland and new-growth forests. They also commonly inhabit old-growth forests and floodplains, although those are less favorable because they lack the spatial and temporal complexity that promotes survivorship. They are found in rainy areas with mild climates and semi-open canopies. They are found at higher elevations than Peromyscus maniculatus in the same region. On small islands, northwestern deer mice are found along the edges of cedar-spruce forest and on beaches where logs, rocks, and debris provide sufficient cover. Northwestern deer mice are medium sized cricetids. Juveniles are a grayish color, while adults are tri-colored. They are brown dorsally and light grey ventrally with tails that are brown dorsally and white ventrally. Northwestern deer mice have long tails (more than 100 mm) and large, naked ears. The tail is slender with short hair and is distinctly bi-colored. Peromyscus keeni is distinguishable from P. maniculatus because of its darker fur color and longer tail (tail length in P. maniculatus is less than 100 mm). Body size in northwestern deer mice is significantly correlated with elevation, with body size peaking at intermediate elevations. Lifespan/Longevity Extreme lifespan (wild) 3 years (high) Average lifespan (wild) 1 years Little research has been conducted on the lifespan of northwestern deer mice. Related species (P. maniculatus, P. californicus, and P. leucopus) have expected lifespans in the wild of days for males and days for breeding females. Some individuals survive to reproduce for a second breeding season. (Botten, Ricci, and Hyelle, 2001; Podlutsky et al., 2008; Ribble, 2003) Behavior Territory Size 2678 m^2 (average) Northwestern deer mice are nocturnal and have a more loosely structured social hierarchy than some of their sister taxa. A rapid growth rate, larger litter sizes, and simple nests contribute to their social structure difference. Males exhibit severe aggression when confronted by other males. Males show aggression towards other males in their territory, submission when in a new territory, and are more prone to initiate grooming when encountering new females. Females show no defensive behavior around their nest unless they are pregnant. In some instances females will share their nest with their younger, reproducing female offspring. Food Habits Northwestern deer mice are mainly granivorous ground foragers. In an intake preference study done on foods from southeastern Alaska seeds from trees, shrubs and fruits were compared as well as fruits for palatability. It was found that salmonberry, stink currants, devil's club seeds, and Sitka spruce seeds were preferred. When diet composition in different ecological habitats was compared, stomach contents did not vary significantly. All diets were composed mostly of fruits and seeds of understory plants, followed by tree seeds and leaf material, with small amounts of arthropods and traces of fungi. Tree seeds become a more important part of their diets during winter and early spring because these mice do not cache food or store seasonal fat. In some areas they eat the eggs of nesting birds, including marbled murrelets

Mice Mus musculus (house mouse)

Rattus rattus (house rat)
Kingdom: Animalia Phylum: Chordata Subphylum: Vertebrata Class: Mammalia Order: Rodentia Suborder: Myomorpha Family: Muridae Subfamily: Murinae Genus: Rattus Species: Rattus rattus Geographic Range Rattus rattus, is found on all continents of the earth. Although the species is believed to be native to India and possibly other Indo-Malayan countries, it has been introduced through human travel overseas to all continents. It is most common in coastal areas because it is a rodent that flourishes in areas inhabited by humans as well as on large ships. For this reason, these animals are often called ship rats. Some other common names for this species include house rat, black rat, and roof rat. Rattus rattus thrives in tropical regions but has been largely driven out of more temperate regions by Noway rats, R. norvegicus. Norway rats, are closely related to black rats, but are more successful in colder climates. However, some data show that R. rattus has been able to adapt to more extreme cold and harsh climate conditions. Habitat Elevation 250 m (high) (820 ft) Rattus rattus is most often found in large numbers in coastal areas because of the way the species is spread through human sea faring. It is generally found in any area that can support its mainly vegetarian diet. Because R. rattus is an agile climber, it often lives in high places, such as top floors of buildings in populated areas or trees in forested areas. Even though it can be found near water, this species rarely swims and unlike its close relatives, rarely finds a home in sewers or in aquatic areas. Although it was formerly common in towns and farms of temperate regions, it has been largely driven out by the more aggressive Norway rat as well as killed off by increasing chemical pest control programs. Data have shown that R. rattus can reach elevations up to 250 m above sea level. Food Habits Rattus rattus generally feeds on fruit, grain, cereals, and other vegetation. It is an omnivore, however, and will feed on insects or other invertebrates if necessary. It consumes about 15 g/day of food and 15 mL/day of water. Because it consumes and destroys the food source during feeding, it can cause devastating damage to farms and livestock. Not only does it gnaw through many materials but it ruins more than that by excreting on the remains of its foraging efforts. Predation Known predators domestic cats (Felis silvestris) Known predators of R. rattus vary depending on environment. In urban or suburban areas, house cats are the main threat to its survival. In less populated areas, birds and other carnivorous animals prey upon it. One possible anti-predator adaptation is the array of color patterns found in this species. Some evidence suggests that color is related to geographical location and therefore ability to remain less conspicuous in the local environment. Also, rats are often aggressive toward other rats. Captive studies have shown R. norvegicus will kill R. rattus. Rattus rattus has a typical threat pose in which it stands on its hind feet and bares its teeth. Ecosystem Roles Impact of these animals on their ecosystems has not been studied. However, we may infer from their feeding habits that they have some impact on plant communities. As a prey species, they may impact populations of those animals which feed upon them. Also, they compete with other species of rodents, such as Rattus norvegicus. Rattus rattus is a disease vector, responsible for bubonic plague outbreaks and other diseases. This cosmopolitan species hosts a wide variety of internal and external parasites, up to 18 species of gastrointestinal helminths in some areas. Economic Importance for Humans: Positive There are no known benefits of R. rattus for humans. Norway rats, the closest related species, is often used for research and as pets.

Rat Rattus rattus (house rat)

Batch of barn owl pellets ready for processing

Skull & jaw bones sorted and awaiting identification

Field Vole Bank Vole Pygmy Shrew Harvest Mouse Water Shrew
Wood Mouse Pygmy Shrew Harvest Mouse Water Shrew Common Shrew

Owl vid #1 Owl vid #2

Using Owl Pellets to Illustrate Energy Transfer from Prey to Predator

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Using Owl Pellets to Illustrate Energy Transfer from Prey to Predator

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Presentation on theme: "Using Owl Pellets to Illustrate Energy Transfer from Prey to Predator"— Presentation transcript:

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