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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 Legend All A points Trails Trails Clearings Clearings Road Monkey River Study Area Road Monkey River Study Area All A points 0 87.5 90 175 180 350 360 525 540 700 720 Meters Meters Grid Cell Count Legend Legend Trails Trails Clearings Clearings Road Monkey River Study Area Road Monkey River Study Area A home range - DP All A points - Grid Cell 20 m X 20 m 0 87.5 175 350 525 700 Meters 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 All A points Trails - Clearings Monkey River Road Study Area 0 90 180 360 540 720 Meters Legend Legend Trails Trails Clearings Clearings Road Monkey River Study Area Road Monkey River Study Area A home range - DP All A points MCP 0 87.5 175 350 525 700 Meters 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 spread Join the points in a tight polygon – subtract lacunae, have program calculate the area Legend June 16 Aug 9 Legend Legend Sept 14 Trails Trails Trails Clearings Clearings Clearings Road Monkey River Monkey River Study Area Road Road Monkey River Study Area Study Area A home range - DP June 16 day range Aug 9 day range All A points - All A ranges 0 87.5 90 175 180 350 360 525 540 700 720 Meters Meters Legend Trails All A points Clearings All A ranges Monkey River Buffer Final DP of day ranges Road MCP of day ranges - Study Area 0 Lacunae to include (<1% of total area) 90 180 360 540 720 Meters Minimum Convex Polygon • • • • Easy to calculate Comparable between sites Overestimates area Longer the study, the larger the area Legend Legend Trails Trails Clearings Clearings Road Monkey River Study Area Road Monkey River Study Area A home range - DP All A points MCP 0 - 87.5 175 350 525 700 Meters 350 525 700 Meters Grid Cell Count • Size of cell greatly influences area • Core use easily calculated Legend Legend Trails Trails Clearings Clearings Road Monkey River Study Area Road Monkey River Study Area A home range - DP All A points - Grid Cell 20 m X 20 m 0 87.5 175 Digitized Polygon • • • • Most accurate Harder to calculate Errors associated with GPS Utilizes both point and line data (sightings and day ranges) Legend Trails All A points Clearings All A ranges Monkey River Final DP Road Study Area 0 90 180 360 540 720 Meters 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 Legend All A points Grid Cell 20 m X 20 m Trails Core Use Area - Clearings Monkey River Road Study Area 0 90 180 360 540 720 Meters Home Range May 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 divergence Aka – partitioning, differentiation Within 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 antiinfanticide) 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 Plants Do primates help or hinder plants? Hinder – flower and seed predators, damage to limbs and bark Help – pollination & seed dispersal Primate – Angiosperm Coevolution?
