Foraging Behavior PDF

Foraging behavior Feeding modes- Herbivore- eats plants Carnivore-eats animals Omnivore- eats plants and animals Detrivore- eats detritus Scavenger- consumes large dead organisms Morphology, physiology, behavior Morphological: Herbivores have longer digestive tracts, carnivores have shorter...

Foraging behavior Feeding modes- Herbivore- eats plants Carnivore-eats animals Omnivore- eats plants and animals Detrivore- eats detritus Scavenger- consumes large dead organisms Morphology, physiology, behavior Morphological: Herbivores have longer digestive tracts, carnivores have shorter tracts and less stomachs. Dentition: herbivores: molars Carnivores: canines Omnivores: have both tooth types Optimal forging theory Null model Evolution- maximize energy return per unit effort More energy= more fitness Cost vs. benefit Reduce cost, increase benefit Find food item: either consume or look for better item Factors related to cost benefit 1. How abundant are food items 2. How abundant are better food items 3. Risk of predation 4. Risk of injury from prey 5. Risk of loss of food to other predators 6. Energy spent in searching and handling 7. Time spent searching and handling Testing example: crows and whelks 35-45 mm whelks: crow's preference Flew 5m above to crack shells More than 5 m high: no more breakage Smaller vs larger Finding food steps: 1. Search time- Find food item in environment 2. Handling time- selection of items, capture 3. Consumption time- consume food item 4. Digestive time- internal process How to \# 2: [records] Field notebook, Voice recorder Video recorder, computers, binoculars/scopes 1.date: month, day, year vs season: winter vs summer 2\. time, start to finish 3\. location: start to finish, distance, path 4\. environment: desert, ocean, forest, cross into different areas 5. Habitat- vegetation type, cover, place in habitat 6. Weather: temperature, wind, cloud cover, humidity, rain/snow/ fog 7. Physical/chemical- salinity, turbidity, pressure, oxygen, currents, pH 8. Descriptions: empirical: physical movement: raising lowering wings Functional: flying- escape flight Spatial orientation- relative to ground, surface Body, another animal, angles and directions Temporal orientation: state- flying, siting, standing Event- taking off, waking up Frequency- \# per unit time duration 9. Changes in methods 10. Notes Organize catalog Ethogram- complete catalog **Search time** Food item: abundant or rare? Food patches: patch size, patch distribution: random, systematic, clumped. Predictable? Finding a patch: random walk- pattern search Evolution- workingon path and flexibility of patch Search paths directed by cues that happen within the search 1\. sight: line of sight, camoflague of prey 2.smell: scent trail (dogs, bears, sharks) 3.Electrical sense: electric field( cartiliogenous fish) 4\. sound follow noise(owls), echolocation (bats, whales) **Handling time** Select and capture Quality(energy=kj) vs quantity(item number) vs risk ( energy spent, ijury, death) Quality and quantity 1 kj item vs 3kj item 2\*3 kj= 6kj 6\*1 kj= 6 kj [Selection] Particulate: particle size, organic content, when to feed, how long to feed Predators: scavenger= not much selection, freshness Catch= prey size, health of prey, defense, location Herbivores: plant species, plant parts (leaves, shoots, roots, flowers, fruit, seeds, bark) Chemical defenses of plants parts i.e leaf veins Specialists: few plant species Generalists: multiple plant species [Capture] Time selection-capture 1.particulate: appendages (tentacles), movement, move environment(pumping water), spin structure\[corals , larvaceans\], place in environment \[ crinoids\] 2\. predators Methods: active pursuit and stalking, sit and wait ambush \[stonefish, snapping turtles\], lure, camouflage of predator \* no movement cooperative \[ hyena, dogs, lions, packs; whales- use bubbles to form fish bait balls.\] **Capture time** Capture- predators Position- front, side, back Killing prey Weapons- morphology, physiology Claws, teeth, spurs Venom- disable-kill: bite; release or hold Structures: entangle Ex. Webs Tools: twigs, spines Herbivores- remove fruits and seeds- crack open Remove leaves and bark- mouth parts Clear cover- snow Consumption time- Particulate- when to move particles to mouth Predators- timing- right away or later Location- where captured, or move prey Ingestion- size of item Orientation Manipulation Herbivores- timing- eat right away, store cache. Ex. Squirrel Location- move material, eat in place Digestive time- apply to all feeding types Retention time- time of passage through gut Manipulation- gizzard, chewing cud Location- move to warmer or cooler place, safe place Activity level- stopfeeding, reduce movement, sleep Polyphenism- multiple distant outcome based on environment Ex. Feeding tiger salamander- change based on density Typical larva- small, eats insects- lower density Cannibal larva- larger, eating other larvae- high density What is "optimal" Interaction with other animals Predation risk\] Competition- in habitat, intra or interspecific Climate conditions Prey quality changes Switching behavior [How to \#3 recording] Notebook Timing device Audio- Notes Record animals: data, playback Photography- film, digital Frames from video ID individuals Measure body position and size Count indivduals Video- digital Speed-normal,slow,high Renew movement Photo/video- control- researcher, animal-motion, remote timer, critter cam Computers- Data storage and banks In lab or field to record Models GPS- on animals On researcher Tag( non telemetry)- external or internal Placement- ear, neck, feet Body cavity Tag type: card, ring/bands Body clipping Id individuals Telemetry tags- collect data, position External or internal Attachment- collars/harness Glue how long? Return signal-backpacks ,satellite Training- observer Practice- recognize behavior Common term Common procedure Observations- mode of operation Contnious- duration Event-based- label events Timebased- intervel Subjects- focal animal- one individual Groups- scan sampling Data sheets Focal, continuous Focal, summary Interval Behavior 1 2 3 ---------- ------------ --- --- Time 1 X 2 X 3 x Scan sample, summary Interval Animal 1 2 3 ---------- ---------- --- --- Time 1 2 x X 3 x x Scan sample