Animal Behaviour Flashcards
What is animal behaviour?
The response an animal makes to an external stimulus.
How is behaviour evolutionary?
It is a part of the phenotype and acted on by natural selection.
Different behaviours can lead to greater survival and reproductive success.
What are proximate causes?
Immediate stimulus and mechanism - what an animal does and how.
What are ultimate causes?
Why an animal exhibits the behaviour, how does it contribute to fitness.
What are Niko Tinbergen’s 4 whys?
Proximate:
1. Causation (what causes the behaviour, what are the anatomical/physiological mechanisms underlying it?).
2. Development/ontogeny (how does the behaviour develop during the animal’s lifetime? Is it innate or learned?).
Ultimate:
3. Function (how does the behaviour help survival and reproduction?).
4. Evolution (history - how did the behaviour arise and how has it been affected by natural selection? How is the behaviour expressed differently in related species, how has it evolved/changed?).
What did Niko Tinbergen show about digger wasps?
Landmarks are used to locate the nest. This visual cue is the arrangement pattern of objects rather than the objects themselves - if pinecones are placed around a nest in a circle, a wasp will orient to a circle of stones rather than a triangle of pinecones.
What are examples of proximate causes?
Genetics - heredity. Neural mechanisms. Hormonal mechanisms. Muscles used. Environment/external stimuli. Precedent events.
What is ontogeny (development) of a behaviour?
How does it change with age?
Interaction of genes and environment?
Is it innate or learned?
What are instincts?
Reflexes/innate responses. Inherited from birth.
What is conditioning?
Learning to respond in a particular way to a stimulus as a result of reinforcement when the correct response is made.
What is reinforcement?
A reward for making the correct response.
What is reasoning?
The ability to respond correctly to a stimulus the first time it is presented.
What is intelligence?
The ability to learn and adjust to situations. Involves short and long term memory.
What are examples of innate behaviours?
Early survival mechanisms e.g. suckling (simple unconscious = reflex).
Nest/web building (complex = instinct).
Reproduction.
Kinesis and taxis.
What are learned behaviours?
Modified by experience.
Variable/changeable with environment.
What are fixed action patterns?
A sequence of behaviour triggered by a specific stimulus (the sign stimulus) that is essentially unchangeable and once triggered, is continued until completion (even if stimulus is removed).
What is the case study for FAPs in male sticklebacks?
Tinbergen, 1951.
FAP = attack other males that invade territory - signalled by red belly (females have grey swollen bellies).
Proximate: red belly is s sign stimulus that triggers aggression.
Ultimate: attacking/chasing away other males decreases the chance that eggs laid in his territory will be fertilised by another male.
What is the FAP in female geese?
Egg retrieval (goose extends neck and approaches egg, the rolls it back to nest using neck/beak). Pattern continued even if egg is removed.
What is habituation?
Where an animal learns not to respond to a repetitive stimulus that conveys little/no useful information. Strength of reaction decreases with repeated presentation of irrelevant stimulus.
Ultimate:
Increases fitness by allowing animals to focus on more important/useful stimuli e.g. food, mates, danger.
What is goose imprinting?
Geese imprint on the first moving/sound-making object that they see after hatching. There is a critical period for social attachment and mate recognition to ensure imprinting on the same species.
What is filial imprinting?
Young animals learn behaviours from their parents.
What is a taxis?
Directional change:
Automatic movement towards (+ve) or away from (-ve) a stimulus, eg phototaxis = movement towards light.
What is a kinesis?
A random change in movement in response to a stimulus e.g. starting/stopping, change in speed, turning more/less.
Sow bugs become more active in dry areas and less in humid ones.
What is rheotaxis?
Stream fish eg trout will face against the current to prevent being pushed downstream.
How does gene mixing in hybrid lovebirds affect behaviour?
Fischer’s build nests with long strips and do not exhibit tucking behaviour.
Peach-faced build nests with short strips and show no tucking.
Hybrids use intermediate length strips and in their first season show unsuccessful tucking behaviour. In later seasons they only turn their heads instead of attempting/failing at tucking.
What is classical conditioning - Pavlov’s dogs?
The dogs learn to connect reflex behaviour (salivating at sight of food) with another stimulus (a bell).
What is operant conditioning?
Trial and error learning. Learning to associate a behaviour with a reward or punishment which follows.
Skinner box - mouse learns to associate pressing a lever with getting a food pellet.
What is insight learning?
An animal uses its experience to respond to a new situation - problem solving.
Chimps - pile and climb up boxes to reach a banana.
What is observational learning?
A certain individual/group shows a behaviour and it passes on to others who observe it.
Blue tits and milk bottles.
What is the ultimate cause of play behaviour?
May facilitate social development or practise of certain important behaviours, as well as exercise.
What is ethology?
The scientific study of animal behaviour.
What is a theoretical approach?
Producing a mathematical model of a behaviour which generates testable predictions/hypotheses. Results (from empirical tests) feedback to refine the behavioural model.
What is optimal foraging theory?
Makes predictions about the types of prey animals should choose or reject, or how long they should spend searching an area for food to maximise food intake rate.
What is the optimal prey choice model for great tits?
Predicts tit behaviour (selecting large/small prey) in different conditions. Encounter rate with most profitable prey determines whether tits take least profitable prey.
Krebs et al, 1978.
What are empirical approaches?
Observation and experimental manipulation to generate testable predictions/hypotheses.
Eg a correlation is observed and experiments are carried out to determine causation. If results are as predicted, there is evidence for causation.
What will happen if there are hereditary alternative behavioural phenotypes in a population?
The better one (which gives a higher fitness) will spread.
What is an adaptation?
A hereditary trait which either spread in the past and is now fixed or is currently spreading due to a selective advantage.
How do we assess whether an adaptation is is better than an alternative?
Cost-benefit approach.
What are examples of adaptations to environments?
- Altitude tolerance.
- Chemical tolerance.
- Cold tolerance.
- Heat tolerance.
- Dry tolerance.
- Fire tolerance.
What are the costs and benefits of mobbing (gulls)?
Benefits: Deter/prevent predators from eating eggs or chicks.
Costs: High energy expenditure, injury or death.
Gulls expected to mob when benefits outweigh costs.
Kruuk, 1964.
How is behaviour studied in the wild?
Biologging.
Accelerometry.
GPS.
What is the accelerometry griffon vulture case study (take off, flight, landing)?
Halsey, Portugal et al, 2009.
What did Common Guillemot penguin accelerometry study show?
Birds don’t flap at a constant rate during diving. Flap rate is high on descent, moderate at the bottom and low on ascent (burst and glide swimming).
Stroke frequency changes with buoyancy.
What is the common eider accelerometry case study?
Shows diving birds take longer to dive when water speed is higher, and takes more effort to get to the bottom.
Heath and Gilchrist, 2010.
What is the green turtle accelerometry case study?
Bell et al, 2009.
What is the 3 toed sloth accelerometry case study?
Rattenbourg et al, 2008.
Which case study: macaroni penguins and physiological response to diving (heart rate/depth)?
Green et al, 2002.
HR increases before dive then drops while diving. After diving it increases again before returning to normal.
How did Pelletier et al, 2007, identify Common Eider flight and dives?
Using heart rate and body temp.
Flight = big peak in HR.
Dives correspond to dips.
How is GPS used?
To measure locations. Useful for monitoring migrations, maybe for conservation e.g. would a wind farm interfere with bird migration?
Shows where animals go and for how long eg for feeding.
What is communication?
The transfer of information from a signaller to a receiver. May be intentional or inadvertent information that is used by individuals of the same or different species.
What are signals?
Traits that evolved for a specific role in communication. Benefit to the sender.
What are cues?
Incidental features present in the environment not intended to convey a specific meaning to a specific receiver. Different individuals may recognise and interpret differently.
Detectable but no benefit to sender.
What does spine elongation signal in naked mole rats (Heterocephalus glaber)?
Dominance and readiness to breed - Queen. Signals others not to breed.
What are states?
Permanently perceptible (not necessarily permanent) eg breeding plumage or antlers. May be handicaps.
What constraints limit the development of signals, meaning signals may indicate fitness?
Energetic and environmental constraints such as holding a territory, foraging. Eg flamingos acquire their pigment (beta carotene) through their diet (shrimp?), so their colour indicates foraging ability.
Signals are acted on by natural selection.
What are some examples of different types of signal?
- Visual (inc. UV).
- Olfactory (eg pheromones).
- Sound (inc. ultrasound).
- Electrical.
- Mechanosensory (inc. vibration).
- Tactile (eg grooming).
What information might be communicated?
- Foraging options - eg bee waggle dance (ref).
- Ownership of territory - eg song or spraying.
- Readiness to mate and mate quality - eg breeding plumage.
- Danger - eg alarm calls (predators) or aposematic signals (I’m toxic don’t eat me).
How do different signals work best in different environments?
In noisy environments, visual is more effective.
In uncluttered environments, auditory is better (sound travels farther).
What happens when a minnow or catfish is injured?
An alarm substance from the fish’s skin disperses in the water and induces a fright response in other fish in the area. Eg minnows will aggregate at bottom of aquarium and become more still.
Why do elephants use infrasound?
It can travel long distances.
What influences how far sound will travel?
Frequency (lower = farther) and temperature (colder = farther).
What is ripple communication used for in water striders?
Courtship, copulatory behaviour, territorial behaviour, sex discrimination.
Examples of eavesdropping?
Squirrel eavesdrops on blue jay - see notes.
Fork tailed drongos (Dicrurus adsimilis) and meerkats - drongos sometimes give false alarm calls (predator warning) in order to steal meerkats’ food, exploitation. Flower and Gribble, 2011.
Dawkins and Krebs, 1978:
Signaller manipulates recipients behaviour without need for physical force, e.g. male cricket sings and female comes to him.
What do flowers advertise?
Rewards for pollinators.
Signals are usually honest but not always, examples of dishonest signals?
- Bee orchid (Ophrys apifera) mimics female bees to trick male bees into pollinating them.
- Batesian mimicry - harmless animals mimic the colouring of toxic species to avoid predation, eg milk snake mimics coral snake.
- Io moth wings are patterned to look like eyes, as of a larger predator.
- Fangblenny mimics cleaner wrasse to attack damselfish (Moland and Jones, 2004) - wrasse and damselfish have mutualistic relationship where wrasse eats parasites from damselfish.
What are examples of honest communication?
- In toads, call freq. indicates snout-vent length, size of toad.
- In koalas, loudness of mating calls indicates male size and fecundity (Charlton et al, 2013).
What are some birds that use UV signalling?
- Budgerigars.
- Blue tits.
- Starlings.
- Reed warbler and cuckoo.
- Owls.
Colouring/patterning appears very different in UV. Some flowers also.
How do animals not overlap auditory communications?
Different animals have different hearing ranges/frequency spectra.
How do bats use sound?
Echolocation.
How do Tiger moths avoid capture by bats?
They can jam a bat’s sonar by clicking. Corcoran et al, 2009.
What is the sexual deception hypothesis?
Male topi antelopes will give false alarm calls in order to keep (oestrous) females from leaving their territory.
Bro-Jørgensen and Pangle, 2010.
What is learning?
The process of acquiring information.
A durable and usually adaptive change in behaviour traceable to a specific experience in the individual’s life.
The behavioural change must be from experience, not development or condition (exhaustion, satiation).
When is learning advantageous?
In environments that change, but not too much. If the environment can be predictable within an animal’s lifespan, learning is worthwhile.
What is an example of habituation?
Alarm call whistles in prairie dogs.
When can habituation be a problem?
If prey habituate to a predator, eg kept in a neighbouring tank.
What is non-associative learning?
Habituation.
Sensitisation.
What is sensitisation?
An increased response to a stimulus after presentation of that stimulus. Eg. if sea slugs (Aplysia) are pinched on the tail, they will quickly withdraw it. After this, touching the tail results in a stronger contraction. Carew, 2000.
How did clever Hans answer questions (arithmetic/word answers by letter chart)?
Using visual cues from the questioner. Could not answer if questioner was in a tent or if questioner did not know the answer. The questioner would involuntarily bend his head forward after asking the question and the horse would start to repeatedly tap his foot. At the correct number of taps the questioner would lift his head up slightly and the horse would stop.
Pfungst, 1911.
Case study - conditioning in Blue Gouramis:
Male blue gouramis can be aggressive, attacking male intruders and repelling egg-bearing females.
Males were conditioned to make mating displays to light by exposing them to light for 10secs and then to females for 5mins. After this, the males were less aggressive to females, and sired more offspring (1000 each rather than 50 for the control group).
Hollis et al, 1997.
Case study - classical conditioning in honeybees:
Bees have proboscis extension reflex (PER) in response to sucrose. Bees were exposed to odour CS+ and then sucrose to condition them to extend proboscis when presented with CS+.
Menzel and Giurfa, 2001.
What is an example of applied classical conditioning?
Aversion therapy used to treat addiction. Positive emotional associations are changed by pairing the addictive substance with an unpleasant stimulus (e.g. an emetic). Has been used to treat minor (e.g. nail biting) and major addictions (e.g. class A drugs), as well as pathological violence.
What is begging behaviour in baby gulls?
Baby gulls peck at red spot on parent’s beak to ask for food. Chicks shown to peck red more than any other colour tested.
Why do urban birds collect cigarette butts for their nests?
Cigarette butts shown to reduce the number of ectoparasites in the nest. Smoked cigarette butts more effective at reducing parasite number than non-smoked.
Suárez-Rodríguez et al, 2013.
What is social learning?
Learning from parents/family, peers, others in the group eg observational learning.
Rats learn to eat hot dogs from observing demonstrator rat.
Honeybees learn where to forage by watching waggle dance.
How do orangutans use tools?
To change the frequency of their calls to sound bigger than they actually are. Would have spread by social learning.
Hardus et al, 2009.
How can pigeons tell the difference between Picassos and Monets?
They have excellent visual acuity compared to humans. All 8 subjects could discriminate between the different styles, but no single cue was identified (eg colour/edges). Some decrease in responding when paintings were reversed (mirror image) or upside down.
How were pigeons trained to discriminate between Monet and Picasso - concept learning?
8 pigeons were shown projected pictures and then had to peck the key beneath the correct one. 10 paintings by each artist were shown. To tests them, new paintings by Monet and Picasso were used, as well as new paintings by other artists eg Cesanne.
What is an example of episodic memory?
Food caching in birds eg Clark’s nutcrackers.
Live in Alpine regions in Western US, storing seeds from pine cones in the summer/autumn and retrieving them in winter/spring. Can store up to 33000 seeds and later recover several thousand.
How was it shown that Clark’s nutcrackers do not just find stores by chance?
Birds had up to 18 seeds to store and 225 storage holes, but with only 18 holes accessible. Some time after caching, the birds were allowed to retrieve their stores, but all 225 holes were then available. This test showed that birds could recover their caches 2-4 times more than expected by chance, and could do this after a delay of 285 days.
Kamil and Balda, 1985.
What is episodic memory?
Recollection of an event taking place in a particular location at a particular time.
What, where and when memories.
What is the Scrub Jay food caching study?
Birds were asked to cache peanuts and mealworms in sand filled ice cube trays surrounded by lego structures. They were allowed to retrieve their stores after 4 or 124 hours. For some birds the mealworms were allowed to deteriorate over the 124 hours, while for others the mealworms were replenished. The study showed that when the mealworms deteriorated, the birds learnt not to search for them after 124 hours, searching more for peanuts, whereas after 4 hours they searched more for mealworms, which they prefer. When the worms were replenished, the birds continued to search more for mealworms than peanuts after 124 hours as after 4. This suggests that the birds remember what they stored where, and when - episodic memory.
Clayton and Dickinson, 1999.
What do serial order learning?
Learning the sequence of stimuli.
Common marmosets, Koba et al, 2012.
What is object permanence?
The understanding that objects continue to exist even when they cannot be observed (removed from sight, hearing etc.).
What are slime mounds good at?
Finding the optimal way to connect points into a network. Slime mound creates network very similar to the actual Tokyo underground network when given the points. Now being used to find new route systems in Iberian Peninsula.
What is Quorum sensing?
Used when a threshold number of individuals initiates copying in the others. When the quorum number is achieved and detected, the decision is made and all follow.
How is quorum sensing used in ants?
Temnothorax albipennis nest in small crevices between rocks. When a nest is broken, a small number of worker ants leave to search for potential new nests. Any scout that finds a new crevice assesses its quality and returns. The longer the scout waits to recruit other ants, the poorer the quality of the site and vice versa. This means that the number of ants will increase quickest at the best site. Once the ants at this site detect that the quorum number has been reached, they return to the old nest site and carry the other ants to the new site, moving the whole colony.
How can chemicals disrupt innate behaviours?
When spiders are exposed to different chemicals, it affects their web-building.
Caffeine and chloral hydrate (sleeping pills) disrupted the webs most severely, more even than marijuana and Benzedrine (speed).
What are examples of cyclical environmental changes?
Days, tides, lunar cycles, seasons.
How do animals synchronise behaviour with cyclic changes?
- Direct response to external changes, e.g. sing when night falls.
- Internal rhythm (biological clock) synchronising behaviour with time (of day or year).
- 1 and 2 combined.
Case study - how do male Teleogryllus crickets decide when to starry singing (rubbing forewings)?
Loher, 1972.
Circadian rhythms entrained by external cues - see notes.
Case study - bees and jam/sugar water?
Forel, 1910 - bees return to breakfast table at same time each day, even when jam was not present.
Von Frisch and Beling, 1920 - used sugar in water to attract the bees, set out at the same time for several days. After, when the sugar water was no longer there, the bees continued to come.
What is an example of circadian rhythms differing within a species?
Long and short winged sand crickets have different rhythms. Juvenile hormone titre in female long wings rises in late afternoon (preparing LW females to fly to find males at night).
Zera et al, 2007.
What type of signals entrain the crickets circadian rhythm?
Visual - preventing visual input to the optic lobe causes males to enter a free running cycle. Loss of connections between the optic lobe and the rest of the brain causes calling to happen unpredictably, at any time. Suggests clock mechanism (zeitgeber) resides in optic lobe.
What part of the brain acts as the zeitgeber (clock mechanism/pacemaker) in vertebrates?
The suprachiasmic nucleus (SCN) in the hypothalamus.
How do circadian mechanisms work?
Environmental cues entrain the clock mechanism/pacemaker via sensory receptors. This leads to observed circadian rhythms eg locomotory, feeding and hormone release patterns as well as other rhythms.
What happens in mammals if the SCN is damaged?
Produces arrhythmic hormone release, feeding and locomotion.
If an arrhythmic hamster gets SCN from foetus, it regains rhythms. If it gets SCN from a mutant hamster with a shorter free-running period (<24hrs), it gains rhythms of the donor.
Ralph et al, 1990.
How does the SCN clock operate?
Rhythmic changes in gene activity. Period gene expression oscillates during the day (conserved from insects to mammals).
Young, 2000.
How is gene expression rhythmic in biological clocks?
Period (per) and Timeless (tim) genes are expressed (clock is promotor for period) and PER and TIM proteins synthesised in cytoplasm form dimers (resistant to degradation by CKIe enzyme) which enter the nucleus and inhibit per and tim expression - self regulation producing oscillating gene activity.
How do PER levels differ between honeybees?
Nurse bees have low PER levels and can perform activities at any time in 24hr cycle, whereas foragers have high PER levels and well defined circadian rhythms.
What is prokineticin 2 (PK2)?
A chemical involved with regulation of circadian rhythms, produced in a strong circadian pattern by the SCN.
Injection into rats’ brains at night shifts their activity pattern from predominantly nocturnal to diurnal.
Cheng et al, 2002.
What is the purpose of having an environmentally entrained endogenous circadian rhythm?
An endogenous clock allows animals to regulate their activity without constantly having to check the environment, however environmental entrainment allows the appropriate adjustment of cycles for local conditions.
Why do naked mole rats have no circadian rhythm?
They live underground in the dark, so no external environmental cues to entrain circadian rhythms. Therefore no adaptive value.
What are examples of circannual rhythms as internal, environment- independent mechanisms?
Golden mantled ground squirrels taken from their natural habitat and kept under constant conditions for years entered hibernation at roughly the same time as squirrels in the wild.
Pengelley and Asmundson, 1974.
Stonechat birds kept under constant conditions in a lab went through reproductive and moulting cycles.
Gwinner and Dittami, 1990.
Why are lunar cycles important?
Nocturnal animals often structure their activity to avoid the brightest nights (full moons) in order to reduce predation.
Katydids are more active on darker, less moonlit nights - Lang et al, 2006.
Kangaroo rats are only active at night when the moon is not shining to minimise predation risk by great horned owls and coyotes - Lockard, 1978.
How do tidal cycles influence behaviour?
Palolo (epitoke) worms only reproduce during neap tides in October and November - endogenous rhythm. Shore crab (Carcinus maenas) daily activity rhythm superimposable on tidal rhythm, max. activity at highest water. This tidal rhythm persists for a week under constant conditions in a lab, but endogenous tidal clock can be restarted by cold shock, even in crabs raised without tides. Palmer, 1973.
How do white crowned song birds anticipate spring (enlarging their gonads for breeding)?
Their clock mechanism is only sensitive to light at certain times, peaking at 16-20 hours. This means system doesn’t activate until days have more than 14-15 hours of light.
How do Rufous winged sparrows (living in the desert) predict the best time to breed?
Waiting for summer rains to begin. Photoperiod increase does stimulate testis growth but testosterone production and breeding behaviour are linked to rains.
Strand et al, 2007.
How do crossbills determine when to breed?
Using food availability as a direct cue. Gonadotropin releasing neurons are active during long days (long photoperiod), so reproduction can be quickly induced when conditions are right.
Benkman, 1990.
What is unihemispheric sleep?
One hemisphere of the brain sleeps at a time while the other is awake and alert (with eye open). Used by dolphins and seals.
Ridgeway, 2002.
What do all animals studies in sufficient detail show about sleep behaviour?
All sleep, and sleep is strictly regulated.
How can sleep be recovered?
- By sleeping longer.
- By sleeping more deeply (e.g. mammalian NREM becomes richer in slow waves).
- By sleep less frequently interrupted.
Examples of animals that don’t appear to sleep for longer if awake/active for longer?
Cockroaches, honeybees and tilapia.
What are the consequences of sleep deprivation?
Prolonged deprivation fatal in rats, flies and cockroaches (rarely in humans). Deprivation always leads to: Sleep intrusion (into waking times). Cognitive impairment (flies, birds, rodents, humans).
How can we conclude that sleep must perform a useful role?
- No animal has been shown to not exhibit sleep.
- All have some form of compensation for extended wakefulness.
- All suffer adverse effects if sleep deprived.
Which physiological parameters show distinct circadian rhythms?
Heart rate and body temperature are examples.
Why is artificial light pollution a problem?
Affects important circadian rhythms in wild animals. Normally, body temperature decreases at night time, important for conserving energy and preserving fat stores to survive winter. Light pollution stops this drop in body temperature, with only a much smaller dip instead.
Can also advance avian reproduction and laying dates - La Tallec et al, 2013.
What are the moon phases?
Apogee (farther from Earth) and perigee (closer). Moon phase can influence singing levels and onset of daw chorus in songbirds.
Where do barnacle geese live?
Their breeding grounds are in the Arctic (constant daylight) and they migrate 3000km to winter in SW Scotland.
What do data loggers show about barnacle geese’s circadian rhythms?
They start when they arrive at their wintering grounds. No circadian rhythms during summer as constant daylight. Low night time HR during the winter. See notes.
What influences nocturnal changes in body temperature and HR?
Combination of moon phase and local weather conditions (not just artificial light which can have an effect).
What is a circadian rhythm?
Any biological process displaying a consistent pattern within roughly 24 hours.
What is free-running?
Most animals do it have a perfect 24 hour clock, so if they are given no cues to entrain to, they will show a drift in day length - free-running.
What is entrainment?
Using time cues to fix their internal rhythms to the external environment.
What is the typical body temperature rhythm of warm blooded diurnal animals?
Lower at night and higher during the day.
When is free-running okay?
In Arctic animals, to take advantage of constant daylight during the summer to feed, mate and rear young.
How do electric eels produce electricity?
Using 3 pairs of abdominal organs. The Main, Hunter’s and Sach’s organs. 2 types of discharge - low and high voltage. Organs are made of electrocytes, lined up to allow a flow of ions (current). Ion channels are opened in electrocytes in response to a signal from the brain via the nervous system. Electric potential difference generates current.
Which of the electric eel’s organs is associated with electrolocation (finding prey)?
The Sach’s organ.
How can the intensity of the electric field between the mouth and tail be maximised in electric eels?
By curling and putting head and tail together.
How often does a foraging star-nosed mole touch its star to the ground looking for prey?
10-15 times per second. It can identify and eat a small prey in only 120 millisecs.
What are the epidermal sensors that cover the appendages of the star called?
Eimer’s organs - touch domes forming mechanosensory system.
What is at the centre of a mole’s star?
The tactile fovea (lower (11th) pair of appendages), used for detailed investigation. Surrounded by larger, lower resolution appendages. Moles constantly shift the nose to explore objects of interest with the tactile fovea.
Why do shorebirds not all compete for the same prey?
There is niche partitioning in bill size and sensory capacities, so different birds are suited to catch different prey.
What structures can be found on some birds’ bills to find prey they can’t see?
Sensory pits with Herbst corpuscles for mechanoreception. Density and number of pits reflects foraging mode.
What factors determine what a bird’s visual field looks like?
How it hunts/forages, nest building, chick feeding. Links to ecological niche.
How are the visual fields different between the visual foraging blue duck and tactile foraging pink eared duck?
Blue duck has larger binocular area and blind spot, as its eyes face more forward in order to see its bill directly in front for foraging. The pink eared duck doesn’t need to see end of bill for foraging, so has its eyes farther back and higher up for max visual coverage to detect predators.
What is the behavioural consequence for having a larger blind spot (visual foragers)?
Increased vigilance time to detect predators (=less foraging time).
Why do vultures collide with wind farm turbines?
They have very large blind spots and narrow binocular areas so can’t see what is directly in front of them. Adapted this way because they typically have to look down for their food and are used to open skies where they would not naturally encounter objects in their flight path (plains, sea). Also have large supraorbital ridges to protect eyes from the sun but which blocks their view. Bustards and cranes have similar characteristics.
How does the visual field of the New-Caledonian crow facilitate tool use?
Their larger binocular area allows them to peer down holes and gives them better depth perception. They can see the end of their beak, allowing tool location and manipulation, they can also see the end of the tool.
Why might a tactile forager eg Knot not have zero blind spot?
In the arctic the ground can be frozen, the Knot would then have to see the end of its beak to catch insects.
What are oilbirds?
The only nocturnal, fruit-eating, flighted bird. They orient using echolocation and have the highest photoreceptor density of any known vertebrate.
What is migration?
The regular, usually seasonal, movement of all or part of an animal population to and from a given area.
What different scales of migration are there?
Intercontinental.
Daily.
Annually.
Once in a lifetime.
Why might animals migrate?
To take advantage of seasonal resources (inc. food supply, especially important for fruit or insect eating birds), to avoid bad/dangerous weather or lack of cover, for better breeding conditions.
What are the cons of migration?
Energetically expensive, risk of exhaustion, exposure to severe weather conditions (dangerous, birds can be blown off course), risk of predation and possible competition over territories.
Why do red eyes vireos have 2 different migration routes from northern USA and Canada to Mexico and SA?
One route crosses the sea, it is quicker but only the birds in the best condition can make the crossing (open sea crossings are more difficult/hazardous). The other route goes over land, and birds in poorer condition must take this longer route.
What is the distance of the annual migration of the Arctic Tern?
90000km.
Where does the Bar-tailed Godwit migrate to and from!
New Zealand and Alaska.
What is the migration route of the Red-necked Phalarope?
Peru to the Shetland Islands (16000 miles).
What types of migration are there (geographical)?
North/South.
Elevational high/low.
Latitudinal inland/shore.
Starlings adult vs juvenile migration case study?
10000 starlings were banded and transported from the Netherlands to Switzerland, and their migration was then documented by recapturing 354 of the birds.
The adult starlings flew NW towards the correct wintering site, but the juveniles that hadn’t migrated before flew SW (the correct direction if they were travelling from the original Netherlands site).
The adults showed true navigation (homing) whereas the juveniles used vector navigation.
Perdeck.
(Similar findings with North American Passerines).
What is true navigation?
When an animal can find it’s way even if experimentally relocated, so it is not using familiar landmarks or s vector.
Case study - pigeons true navigation.
Pigeons were transported under tightly controlled conditions so that they couldn’t perceive any navigational information. They all however made it back home.
Walraff, 1980.
What is the map and compass model of navigation?
Homing is a 2 step process using a mechanism to identify spatial position (map) and another to identify directions (compass).
What information can animals use to navigate?
The Sun.
Stars.
The magnetic field.
Polarised light.
How do birds use magnetic fields to navigate?
They have cryptochromes in their photoreceptors which are involved in magnetic orientation. Cryptochromes form pairs and spin when exposed to blue light - see notes.
Magnetoreception depends on a clear image from which eye?
The right. If this eye is covered, birds become disorientated, however if the left is covered, they can still navigate well. Vision is therefore required for the robin’s internal compass to work, and darkness stops the magnetoreception.
Which compound, present in beaks, eyes and brain, has a (suggested) role in magnetic field sensing?
Iron deposits - magnetite.
What happens to birds angle of migration when the apparent position of the sun is altered?
Birds use the sun as a navigational cue, migrating in the direction at a specific angle from the sun. When it’s apparent position is altered using mirrors, the birds shift their migratory direction according to the shifted sun position.
Kramer.
How does polarised light inform navigation?
The direction the polarised light comes from indicates the direction of the sun (90*).
How does the sun compass compensate for the changing position of the sun?
Time compensation - the sun compass is tied to the bird’s circadian clock. Readjusting the clock therefore causes them to make predictable mistakes.
Why can birds with shifted circadian clocks mistake a noon sun for a sunrise?
They don’t consider the sun’s elevation, only the azimuth direction (point on the horizon directly below the sun).
Birds must learn the sun’s path (E to W) to use the sun compass, how might they do this?
They may use a magnetic compass to determine the directions of the azimuth.
How can birds use stars to tell direction?
Stars rotate around Polaris (the North Star), so the centre of rotation shows birds which way is North.
Why is a star compass useful?
A sun compass doesn’t work at night, when many birds migrate.
What happens to birds’ migratory orientation when they grow up without seeing a point source of light (no night sky)?
They show no directional orientation.
What happens to birds’ migratory orientation when they are exposed to a manipulated night sky where stars rotate around Betelgeuse?
They show a migratory orientation away from Betelgeuse rather than the North Star.
Which side of the nose is more important for olfactory navigation?
The right. When this side is blocked, the route is slower with more stops.
What happens to pigeons’ homing flights after repeated releases?
They become more efficient.
What is the honeybee waggle dance?
A figure of 8 shaped sequence of movements used by successful forager bees to communicate the distance and direction of a profitable flower patch for food.
How does the waggle dance encode distance?
The duration of the waggle run phase of the dance indicates to the followers how far the flower patch is.
How does the waggle dance encode direction?
Waggle runs are orientated towards the flower patch.
What are the Apis species?
- mellifera - western hive bee.
- cerana - eastern (Asian) hive bee.
- dorsata - giant honeybee/rock bee.
- florea - dwarf honeybee.
Florea branched off first, then dorsata, cerana and mellifera diverged last (sister species - similar appearance and ecology).
Where did the waggle dance evolve from?
In bumblebees (Bombus terrestris), which branched off before the Apis group, successful foragers do exited runs on the nest to advertise food. The dance becomes more sophisticated/informative in later diverging species of the Melipona, with the waggle dance evolving after the Melipona branched off, as it is seen only in the Apis species. Chittka and Dornhaus, 1999.
How do bees orientate their dances?
Using a light cue - sun’s azimuth provides direction.
If no light cue is available (under experimental conditions) bees are unable to correctly orientate their dance.
They also require a horizontal surface of comb to properly indicate direction.
How can foraging success be measured?
Monitoring the daily weight changes of a beehive - which mostly reflects nectar intake and therefore foraging success.
In which habitat is dance communication most beneficial and why?
Tropical. There was a much higher % of days with weight gain for orientated bees than with disorientated bees (no light source given).
Much less difference between orientated and disorientated bees in temperate Central European and Mediterranean habitats. This is because foraging sites are more evenly spread in temperate habitats.
Dornhaus and Chittka, 2004.
Where did honeybees originate?
In tropical Asia. The waggle dance would have evolved there as it is most beneficial in tropical habitats. Some honeybee species have since adapted to temperate habitats.
How is waggle dancing used in nest site hunting?
Scouts assess quality of prospective nest sites and report the location and quality by waggle dancing. Scouts compare competing sites and choose the best one by dancing. This means waggle dancing is still important even in temperate habitats where social foraging isn’t a significant advantage.
What are the advantages of pecking orders?
- Decreases amount of individual aggression - one animal gives way to another, then no fighting.
- Avoids injury to stronger individuals.
- Ensures resources are shared out so that the fittest survive - high rank = more resources.
- Increases genetic vigour of the group - dominant male gets more mates.
How is position in a pecking order determined?
Status decided by agonistic behaviour other than fighting. Size, strength, fitness and aggressiveness may have influence.
Position also depends on age, sex, personality, intelligence and number/status of relatives.
Status is learned.
When are dominance hierarchies useful?
When resources are limited (but not scarce - cooperation would then be better) and concentrated (if scattered, speed more important than aggression in competition).
What is agonistic behaviour?
Threatening behaviour/rituals and sometimes combat.
Caused by conflict over food, mates or territories.
What are the types of dominance hierarchy?
- Linear.
- Triangular.
- Complex - eg hareems.
- Despotic.
What is selfish herd theory?
All individuals head for the centre of the group when a predator is detected (safest place).
King et al, 2012.
What techniques do pigeons use for homing?
- Landmark and compass.
- Olfaction.
- Magnetic field.
Groups home quicker than solo.
What is hierarchical decision making?
All individuals have input into group’s movement, but some individuals’ votes carry more weight.
What are the distance dependent behavioural zones?
- Zone of attraction - avoid becoming isolated, stay in group.
- Zone of alignment - take same direction as those close by.
- Zone of repulsion - move away from very close neighbours, avoid collisions.
How do bee swarms coordinate?
A small group of informed bees lead a much larger swarm, eg 150 can lead 3000.
Guides streak through the swarm to lead uninformed bees in the right direction. These streaker bees move much faster than the rest.
What is the many wrongs hypothesis?
If more individuals contribute to the decision (with equal or similar weight), the accuracy of the decision increases.
Which individuals may be leaders?
- Better informed.
- Dominant or older.
- More in need (eg hungry).
- More stubborn.
What are the functions of flocking?
- Information sharing - eg foraging spots, roost, mates.
- Navigation - follow a leader.
- Energetic - take advantage of aerodynamic interactions to save energy.
- Predation - less chance of being eaten in a larger group.
Why do birds fly in V formation?
Fixed-wing aerodynamic theory, 45 degrees and ~1.2m out
Portugal et al, 2014.
Spatial/temporal phasing of wing beats -> wing tip path coherence and energy savings (wing tip vortices = updrafts/downdrafts). Phasing depends on spanwise and streamwise position. Positive feedback keeping birds in correct position?
Birds take turns in best positions.
How are cluster formations different to Vs?
No energy savings, but better navigation and faster homing than solo.
Harder work for birds at back and birds do not move around, so not equitable like Vs.
What are the benefits and costs of living in groups?
Benefits:
1. Anti-predator benefits - many eyes = more chance of detecting predators and lower individual vigilance times. Also dilution effect = less individual risk.
2. Better foraging for predators in groups.
3. Possible energy savings (aerodynamics, huddling) and better navigation.
Costs:
1. Worse foraging - increased competition, kleptoparasitism, getting in each other’s way, disturbing each other’s prey.
2. Parasites/disease.
3. Possible higher social vigilance (kangaroos, Favreau et al, 2010).
4. More conspicuous, increased predation risk?
5. More aggression likely in larger groups.
How does position in group affect vigilance time?
Animals at centre less vigilant (often dominant individuals) - ring-tailed coati, Blanco and Hirsch, 2006.
Safer position?
What is predator swamping?
Dilution effect - saturate predators by all coming out at once:
- Synchronous emergence of adults, eg mayflies and cicadas.
- Synchronous spawning, eg corals and palolo worms.
- Synchronous birthing, eg sheep and wildebeest.
What is predator confusion?
Predators find it harder to pick out one individual from a group, so attack:kill ratio drops as group size increases.
Neill and Cullen, 1974.
Fish shoals and bird flocks in flight compact in response to predators - makes singling one out even harder.
What is the advantage of mobbing behaviour in groups of nesting birds?
Reduces egg/chick predation compared to isolated nests. Communal defence.
Picman et al, 1988.
What are the benefits of living in groups for predators?
- Larger lion prides and African wild dog packs can defend kills from hyenas for longer.
- A coalition of male lions can hold a pride for longer than a single dominant male.
- Groups of predators can successfully take down prey that they couldn’t alone - better foraging success and larger/difficult prey can be caught.
- Jack fish foraging success (prey anchovies) increases with group size, but fish at the front benefit most. Major, 1978.
- Huddling to conserve heat and water (save energy) in Emperor penguins. Also in burrows to create warmer microclimate, eg mice, voles, naked mole rats (small and high SA).
Why might larger groups have more predation?
- More conspicuous.
- More likely to contain an individual in poor condition, eg injured.
- More likely to be out in the open.
- More intraspecific predation (egg eating).
But not always, small groups may also have higher predation.
What is altruism?
Being helpful to others at a cost to yourself.
Donor increases fitness of recipient and decreases their own fitness.
Can evolve by natural selection because helping a close relative means they can pass on genes that you share. Therefore not selected against.
Why does offspring recognition evolve more in colonial than solitary species?
Higher risk of misdirecting parental care. High cost with low benefit.
Solitary birds more likely to accept strange chicks.
What is the coefficient of relatedness?
The probability that an allele in one individual is present in another because both inherited it from a shared, recent common ancestor (identity by descent).
Half siblings, nephews and nieces: 0.25.
Cousins: 0.125.
What are direct and indirect fitness (inclusive fitness)?
Direct: personal reproduction.
Indirect: additional reproduction by relatives made possible by individual’s actions.
What is Hamilton’s rule?
Altruistic behaviour will spread if rB>C.
What are the benefits/costs of giving alarm calls?
Warns other individuals but may attract predators attention to self.
Belding’s ground squirrels give 2 alarm calls:
Predator is a mammal = trill (increases predation risk - altruistic).
Predator is a hawk = whistle (decreases predation risk - selfish).
Sherman, 1985.
Black-tailed prairie dogs are more likely to give alarm calls when kin are nearby, especially offspring.
What is reciprocal altruism?
Not true altruism, delayed gain in direct fitness.
Cotton-top tamarins are more likely to help a partner if that partner is helpful to them. Hauser et al, 2003.
Vampire bats (females and offspring that roost together).
Conditions for evolution:
1. Cost to actor smaller than or equal to benefit to recipient.
2. Individuals who don’t reciprocate are punished (vampire bats won’t be fed if they don’t share, so die if unsuccessful at hunting for 3 nights).
Most likely when:
1. Repeated interactions with same individuals (social).
2. Many opportunities for altruism/reciprocation in lifetime (long-lived) and symmetrical situations.
3. Good memory (intelligent).
Less likely in species with dominance hierarchies.
Altruistic behaviour and relatedness in male cichlids:
Spend longer guarding nest (foregoing additional mating opportunities) when mated with sister than an unrelated female.
Thünken et al, 2007.
How do male pied kingfishers increase their inclusive fitness?
Year old males that don’t find a mate can help out at their parental nest (feeding siblings) - primary helpers, or at an unrelated nest - secondary helpers.
Primary helpers work much harder than secondary helpers, delivering almost as much food as the father.
Reyer, 1984.
How are naked mole rats unusual mammals?
- Nearly hairless and ectothermic.
- Eusocial (highly inbred).
- Can digest cellulose due to bacteria in gut (like termites).
- Use teeth (not feet) to burrow.
- Can run backwards the same as forwards.
What is eusociality?
Social systems with:
1. Overlap in generations.
2. Cooperative brood care.
3. Specialised castes of non-reproductive individuals.
Has evolved twice independently in the Bathyergidae family (inc. naked mole rats).
What is reproductive altruism in naked mole rats?
Only one queen and several kings reproduce. All other females and rest of males reproductively suppressed by queen.
Helping to raise offspring may be adaptive as relatedness in the colony is high (queen often mates with brothers). Also, opportunities to disperse and set up new colony are few and risky.
What are the castes of naked mole rats?
- Queen - reproduces.
- Small non-breeders - excavate, build nests, forage.
- Large non-breeders - defend the nest (against snakes and other mole rats).
How do naked mole rat queens maintain control/eusociality.
Physical dominance/intimidation.
Shove slow workers to increase their pace (but more likely to shove more distant relatives).
What benefits are there to females of mating with multiple males?
Genetic:
Female seeks EPCs with males of a higher genetic quality than her partner to improve offspring viability.
Mating with multiple males increases the genetic variety of sperm available to fertilise her eggs, more chance of getting especially compatible sperm to complement her eggs, eg better immune systems for offspring - EP bluethroats have stronger immune response than WP (Johnsen et al, 2000).
Non-genetic:
May receive more resources/care from males.
Uncertainty over paternity reduces the chance of infanticide.
Multiple matings may produce more young eg pseudoscorpions (Zeh, 1997).
Or young with better survival eg wild guinea pigs (Hoffman et al, 2003).
What are the costs to females of mating with multiple males?
Higher chance of sexually transmitted disease - degree of polyandry correlates with WBCs (Nunn et al, 2000).
When are males choosy?
When males are main investors. Male katydids only mate once using an edible spermatophore, which is up to 25% of his body mass. Females can produce multiple clutches. Choosing bigger females = more eggs fertilised (Gwynne, 1981).
What are the theories of why females provide more parental care?
- Association theory:
With internal fertilisation, female more closely associated with offspring, leading to higher investment. - Paternity theory:
With internal fertilisation, female is assured of maternity, but male cannot be certain the offspring are his (female may have ‘cheated’). - Order of release:
With internal fertilisation, male has first chance to desert and leave female to care for the young.
With external fertilisation (fish) the reverse.
Widow birds case study?
Andersson, 1982.
Euplectes progne.
Female choice -> runaway selection as gene for trait and gene for preference increase together. Attractive trait then passed on even if not beneficial to offspring.
