community ecology ranging behavior intergroup interactions interspecies interaction predation...
TRANSCRIPT
Community Ecology
Ranging Behavior
Intergroup Interactions
Interspecies Interaction
Predation
Primates & Plants
Home Range
The entire range of a group of animals
The widest area in which a group of animals travel
A circumscribable area in which all daily and seasonal activities take place
Longer studies tend to have longer home range estimates for the species
Determining Home Range
1. Grid Count Method - Mark the position of the animals on a map, superimpose a grid, count the # of grids entered, calculate area
2. Minimum Convex Polygon - Mark the position of the animals on a map, draw a polygon around all the points, calculate the area of the polygon
3. Digitized Polygon
Legend
Trails
Clearings
Road
Study Area
Monkey River
All A points 0 175 350 525 70087.5Meters
0 180 360 540 72090
Meters
Legend
All A points
Trails
Clearings
Monkey River
Road
Study Area
Grid Cell Count
Legend
Trails
Clearings
Road
Study Area
Monkey River
A home range - DP 0 175 350 525 70087.5Meters
Legend
Trails
Clearings
Monkey River
Road
Study Area
All A points
Grid Cell 20 m X 20 m
Determining Home Range
1. Grid Count Method - Mark the position of the animals on a map, superimpose a grid, count the # of grids entered, calculate area
2. Minimum Convex Polygon - Mark the position of the animals on a map, draw a polygon around all the points, calculate the area of the polygon
3. Digitized Polygon
0 180 360 540 72090Meters
Legend
All A points
Trails
Clearings
Monkey River
Road
Study Area
Legend
Trails
Clearings
Road
Study Area
Monkey River
A home range - DP 0 175 350 525 70087.5Meters
Legend
Trails
Clearings
Monkey River
Road
Study Area
All A points
MCP
Determining Home Range
1. Grid Count Method - Mark the position of the animals on a map, superimpose a grid, count the # of grids entered, calculate area
2. Minimum Convex Polygon - Mark the position of the animals on a map, draw a polygon around all the points, calculate the area of the polygon
3. Digitized Polygon
Digititzed Polygon
Tag and take a location reading of each tree in which the animals are seen (Long/Lat or UTM) using GPS
Import into GIS software (ex ArcGIS)Put a buffer around each point (or around the
day ranges) = to average group spreadJoin the points in a tight polygon – subtract
lacunae, have program calculate the area
Legend
Trails
Clearings
Road
Study Area
Monkey River
A home range - DP 0 175 350 525 70087.5Meters
Legend
June 16
Aug 9
Sept 14
Trails
Clearings
Monkey River
Road
Study Area
Legend
Trails
Clearings
Road
Study Area
Monkey River
A home range - DP 0 175 350 525 70087.5Meters
Legend
June 16
Aug 9
Sept 14
Trails
Clearings
Monkey River
Road
Study Area
June 16 day range
Legend
Trails
Clearings
Road
Study Area
Monkey River
A home range - DP 0 175 350 525 70087.5Meters
Legend
June 16
Aug 9
Sept 14
Trails
Clearings
Monkey River
Road
Study Area
June 16 day range
Aug 9 day range
0 180 360 540 72090Meters
Legend
Trails
Clearings
Monkey River
Road
Study Area
All A points
All A ranges
0 180 360 540 72090Meters
Legend
Trails
Clearings
Monkey River
Road
Study Area
All A points
All A ranges
Buffer of day ranges
0 180 360 540 72090Meters
Legend
Trails
Clearings
Monkey River
Road
Study Area
All A points
All A ranges
Buffer of day ranges
MCP of day ranges
0 180 360 540 72090Meters
Legend
Trails
Clearings
Monkey River
Road
Study Area
All A points
All A ranges
Buffer of day ranges
MCP of day ranges
Lacunae to include (<1% of total area)0 180 360 540 72090
Meters
Legend
Trails
Clearings
Monkey River
Road
Study Area
All A points
All A ranges
Final DP
Legend
Trails
Clearings
Road
Study Area
Monkey River
A home range - DP 0 175 350 525 70087.5Meters
Legend
Trails
Clearings
Monkey River
Road
Study Area
All A points
MCP
Minimum Convex Polygon• Easy to calculate• Comparable between sites• Overestimates area• Longer the study, the larger the area
Legend
Trails
Clearings
Road
Study Area
Monkey River
A home range - DP 0 175 350 525 70087.5Meters
Legend
Trails
Clearings
Monkey River
Road
Study Area
All A points
Grid Cell 20 m X 20 m
Grid Cell Count• Size of cell greatly influences area• Core use easily calculated
0 180 360 540 72090Meters
Legend
Trails
Clearings
Monkey River
Road
Study Area
All A points
All A ranges
Final DP
Digitized Polygon• Most accurate• Harder to calculate• Errors associated with GPS• Utilizes both point and line data
(sightings and day ranges)
Home Range
Related concepts/measures
• Core area – areas in which the group spends disproportionately large amounts of time – ex main feeding trees, sleeping trees, water holes. Areas integral to daily life.
• Daily Path Length or Day Journey Length – distance an animal or group travels in a day
Core Area
0 180 360 540 72090Meters
Legend
All A points
Trails
Clearings
Monkey River
Road
Study Area
Grid Cell 20 m X 20 m
Core Use Area
Home RangeMay or may not be defended, in
part or whole
The part that is actively defended and exclusively used we call a territory
Some animals are not territorial – they do not actively defend or exclusively use any area.
Territory
Area that is actively defended and exclusively used
Territoriality – the behavior (active defense and exclusive use) associated with the territory
Territoriality – expressed in at least 4 ways
1. Scent Marking - marmosets
2. Vocalizing - howlers
3. Display - gibbons
4. Physical Confrontation – chimpanzees
Functions of Territoriality?(agonistic between group interactions)
1. Defence of food supply (females)
2. Defence of females (males)
3. Protection against infanticide
4. Phylogeny
5. Link to monogamy?
Different explanations in different cases – probably not a single phenonmenon
Intergroup Interactions
Range from very friendly in some species to very aggressive in others
• Some regularly join up and form supertroops (ex hamadryas, geladas)
• Some are violently territorial – chimps?
• Some groups have extensive range overlap and just avoid each other
Intergroup Dominance
• When one group is able to consistently displace another group regardless of where they meet
• Between group competition
• Which group is dominant depends on group size, sometimes the number of adult males
Interspecies Interactions
Allopatry – when the geographic ranges of 2 species do not overlap. They are geographically separated from one another. Ex. Lemurs and lorises.
Sympatry – when two or more species have overlapping geographic ranges. Result is competition for resources. More closely related the species, the more intense the competition. Ex. Spiders, howlers, cebus
Competitive Exclusion
Complete competitors cannot coexist
Animals with similar needs, living in the same place, must find ways to reduce the direct competition
Niche divergenceAka – partitioning, differentiationWithin the same general area, there many be many
distinct habitats, and many distinct ecological niches.
Niche divergence allows similar species to reduce competition through separation of some or many aspects of their ecology.
Ex – slight differences in diet, forest strata, activity patterns
Two kinds of competition
1. Outright interference (contest) – usually involves aggression (chasing etc). Sympatric primates sometimes form interspecific dominance hierarchies (ex spiders & howlers in Costa Rica)
2. Exploitation (scramble) – trying to exploit a resource that others have already exploited/eaten. General reduction in available resources.
Effects of Interspecific Competition
The less successful competitor will generally experience a reduction in any/all of these:
• Population density
• Geographic distribution
• Ranging patterns
• Dietary diversity
Benefits of Interspecies Interactions
• Access to otherwise inaccessible food sources
• Increased predator detection and warning
• Improved competitive ability
• Social benefits?
Predation
Assumed to be a major force in primate behavior and social life
Actual data on predation risk or threat is
Actual reports of predation on primates are rare
Reports of predation on primates are rare because
• Predators avoid humans – predation does not take place when we are there
• Many predators hunt at night
• We are normally studying the prey, not the predators (chimp/colobus exception)
• Maybe predation is actually rare? Not likely.
Indirect Evidence
The existence of regular, predictable predator defence behaviors & other adaptations
• many small primates are cryptic
• many are vigilant
• all have alarm calls
These things only make sense if we assume that there is predation pressure
Predation and Infanticide
Similar pattern – Theoretically – both are credited with being a major force in the evolution or primate social life.Empirically – both are relatively rare behaviors and thus we have relatively little good solid quantitative data Actual evidence - both rely on the existence of counterstrategies (anti-predator and anti-infanticide)
Primates as Prey
Predators that prey on primates:
• Carnivores (big cats, wild dogs)
• Crocodiles at waterholes
• Raptors (hawks, eagles)
• Snakes
• Other primates
Primates as Predators
1. Humans - everything
2. Chimpanzees – galagos, bushbabies, blue monkeys, red tail monkeys, baboons, black and white colobus, red colobus (35 types of vertebrate animals)
3. Baboons - small deer & vervet monkeys
4. Blue monkeys – galagos & bushbabies
Primates and PlantsDo primates help or hinder plants?
Hinder – flower and seed predators, damage to limbs and bark
Help – pollination & seed dispersal
Primate – Angiosperm Coevolution?