Chap. 13 Habitat selection, territoriality and migration

鄭先祐 (Ayo) 教授國立台南大學 環境與生態學院

生態科學與技術學系 環境生態研究所 + 生態旅遊研究所

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Habitat selection, territoriality, and migrationModels of habitat choice

The ideal free distribution model(IFD) and habitat choice

The IFD model and foraging successTerritorialitymigration

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Habitat selection, territoriality and migration

Habitat selection The decision-making process is

complicated. • Mates, food, and predators

Home rangeNomads ( 遊牧民 ), constantly

wandering and never returning to the same place with any regularity.

Territory: an area occupied and defended by the owner. To keep intruders outside of this area.

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Model of habitat choice

The ideal free distribution model (IFD) and habitat choice Habitat 1(H1) with resource 1(R1) Habitat 2 (H2) with resource 2 (R2)

• At equilibrium, R1/N1 = R2/N2• Resource matching rule

The IFD model and foraging success Stickleback fish Mallard ducks

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The matching resource rule in stickleback fish

Experiments ： Each tank had two feeders that distributed food at opposite ends of a tank. Two treatments

• food (water fleas) were released from the two feeders in a 5:1 ratio

• the ratio was 2:1.

Results: the fish distributed themselves under feeders in a ratio similar to the resource matching rule (Fig. 13.2)

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In mallard ducks

Two observers who were stationed 20 meters apart throw bread (food) into the pond. When equal amounts of food were thrown

into patches by both observers, ducks quickly distributed themselves in a 1:1 ratio (Fig. 13.4).

When one patch had twice as much bread as the other, the ducks distributed themselves in a 2:1 ratio.

But not all individuals were receiving the same amount of food across patches.

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The two foraging patches created when two individuals threw bread into a pond from different locations had equal profitability. The dashed line represents the predicted number of ducks at site 1.

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Group Territoriality in chimpanzee

Group territoriality, are defended by a group of unrelated individuals. Between-group raiding ( 侵襲 ) To be War-like Larger group eradicating( 消滅 ) a smaller

group of chimps.

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Territoriality and learning in Anolis lizards

材料： Anolis aeneus lizards (Stamps, 2001) Despite numerous experiments manipulating food

availability, she did not uncover a clear-cut effect of food availability on territory formation.

Rather, she found that safety from predators and suitable temperature appeared to be the most important attributes of a desirable territory.

How do juvenile lizards determine which territories are suitable with respect to temperature and predation pressure?

Do lizards learn what areas are best from their interaction with other lizards?

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(A) Juveniles not only spent more time on experimental (E) versus control (C) homesites, but they also arrived at experimental homesites more quickly

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(B) Juvenile lizards were drawn to experimentally manipulated homesites (E) over control (C) homesites.

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Territoriality and learning in Anolis lizards

Conspecific cueing hypothesis A juvenile would be allowed to observe two very

similar territories, one that was currently occupied and one that was vacant.

When given the choice between these two areas, with the territory owner now removed, juveniles showed a strong preference for the previously inhabited area.

The other juveniles displayed no preference for the previously occupied territory.

A strong visual component to conspecific cueing in A. aeneus.

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Territory owners and satellites in pied wagtails

Territory ownership often requires constant vigilance ( 警戒 ) against both predators and conspecific intruders.

Owners, satellites, and territory defense in pied wagtails.

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Fig. 13.8 pied wagtails and food search.

Pied wagtails systemically search for food on their territories along riverbanks (A) a single bird can complete a circuit of

the riverbank in 40 minutes and gets all the food it finds

(B) when a territory is shared by two birds, however, the circuit is divided up as well, and so each bird primarily gets the food that it finds in its 20 minutes of walking the riverbank.

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Owners often allow “satellite” individuals to forage on territories. Some territorial defense is provided by the satellites.

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How to keep a territory in the family

Fig. 13.9 Scrub jays and territories.

Territories are “inherited” across generations, leading to the establishment of “family dynasties”.

Territory size is increased through a process called budding.

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Migration and navigation

Navigation The sun compass By the stars The Earth’s magnetic field

The heritability of migratory restlessness

Defense against parasitesPhylogeny

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(A) Here we see migration in geese

(B) gnu.

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Migration and the sun compass

Monarch butterflies migrating each year fro North America in the mountain ranges of central Mexico. During their annual migration, the branches of

trees have been known to collapse from the weight of too many butterflies (Fig. 13.11).

Monarch butterflies traverse up to 6,000 miles on their migratory trip, and they almost always navigate successfully without getting lost, even on their first migration.

To examine the role of solar navigation in the Monarch butterflies. ran a classic “clock-shift” experiment

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Monarch butterflies

Raised two group of monarch butterflies in a laboratory One group was slowly shifted the

butterflies’ body clocks bake six hours. The second group, were not shifted

During the period of autumn migration, released them The control butterflies headed south The clock-shifted butterflies, however,

flew almost due west. (Fig.12.12)

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Clock-shifted butterflies fly west

Laboratory raised butterflies, who were raised on a normal light-dark cycle

Butterflies from natural populations fly south

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The pipe at the bottom of the simulator directed a constant flow of air up toward the butterfly so that it could fly; a video camera was connected to the bottom of the simulator; an encoder was attached to the butterfly from the top of the simulator and was connected to a computer that kept a timed record of all the butterfly’s movements.

With this setup, researchers could track the direction the butterfly was orienting toward and whether it was actively flying or gliding.

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Indigo buntings and navigation by the stars

Emlen began by creating funnel-shaped test cages for buntings, at the bottom of which he placed an ink pad.

The cages were constructed such that each time a bunting tried to fly out, the location of its footprint was marked by ink, and so its orientation pattern was easily recorded (Fig. 13.15)

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The Earth’s magnetic field

Evidence that the magnetic field of the earth is important in migration has been found in a wide diversity of animals, including birds, amphibians, reptiles, and insects.

Bobolink (rice bird) has one of the longest round-trip annual migrations of any animal– 12,400 miles. These birds spend the summer months in the

northern US and Canada and then undertake a migration to South America (primarily Brazil, Paraguay, and Argentina) before they return to the Northern Hemisphere.

Do they use the magnetic field of the earth?

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Magnetic fields and bobolinks

Bringing birds into a planetarium and projecting the star patterns, also to manipulate the magnetic polarity. When the visual cues and magnetic polarity

provided the same information, the birds oriented in the correct southern direction.

A visual cues were correct, but the magnetic polarity was reversed, birds headed toward the magnetic south.

• Magnetic cues were critical in the annual round-trip migration.

• High levels of an iron-rich, magnetically sensitive substance in bobolinks.

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The heritability of migratory restlessness

Compared the onset of migratory activity between laboratory and wild birds in 18 different species. A strong correlation between onset of migratory

activity in both groups of birds, suggesting that the timing of departure for migration may be under genetic control.

Migratory restlessness during the autumn migratory season. Collected 40 blackcaps from the field The 10 birds with the latest dates for migratory

restlessness were selected and allowed to mate. They produced a total of 26 offspring, and from that group 4 pairs with late-onset migratory birds.

In only two generations, migratory restlessness was delayed for an average of 7.65 days (Fig. 13.17)

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In each generation, German blackcap birds with the latest onset of migratory activity were chosen to breed. In just two generations, the onset of migratory activity was set back more than a week.

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Defense against parasites

The energy expended during long migration can reduce immune responsiveness, making animals more susceptible to disease. In addition, long-distance migrants also face new

parasites and diseases upon arrival at their migratory end point.

Migratory birds should therefore invest more heavily in immune function compared to related resident relatives. (hypothesis)

Test:• the bursa of Fabricus was larger in birds from the

migratory species, while in nine of thirteen pairwise comparisons.

• The spleen was larger in birds from the migratory species.

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Phylogeny and migratory behavior

In the avian family Motacillidae Evolutionary precursor model of migration

Migration will be associated with species that live in open or edge habitats (so-called non buffered areas) rather than species that live in forests (buffered areas).

The pied wagtail The golden pipit The yellow-throated longclaw

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Evolutionary precursor model

49 spp. In the Motacillidae family As either “migratory” or “sedentary”, and their

habitat as either open/edge or forest. They found that

there was no association between habitat in terms of open/edge versus forest

Species that were associated with open/edge habitats were no more likely to migrate than were species that lived in the forest.

Species that lived at higher altitudes were much more likely to migrate than species that live at low altitudes.

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Interview with Dr. Judy Stamps

Of all the systems you could have chosen to study territoriality, how did you end up working with small lizards?

Dr. Judy Stamps is a professor at the University of California at Davis. Her long-term work on lizards and territoriality has produced fundamentally new ideas on both territoriality and the role of learning in territory formation.

Ayo NUTN website:http://myweb.nutn.edu.tw/~hycheng/

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