Impacts Of Habitat Loss, Fragmentation And Degradation On Primates/ Another Spp Group. Traits That Make Them More Susceptible?

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Strier 2007

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Primates slower rates of development than other mammals

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life history

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All primate infants breastfed by others, rely on them heavily. Have longer juvenile period btw weaning and sexual maturity. Can use tree holes for nesting and park juveniles in leafy patches whilst foraging. More susceptible as juveniles to hunting and predation. Longer life spans than similarly sized mammals. Slower metabolisms. Most include fruit in their diet. Some are leaf eaters e.g. howler monkeys. Chimp preys on other primate spp. Evolved from arboreal animals; spend most of their lives in trees. They account for 25-40% of fruit-eating animals in tropical RF. Some partially terrestrial e.g. baboons, few are fully. o As they reach sexual maturity later and have longer period btw births, they recover more slowly after being depleted by poaching/ pet trade.

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threatened

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More than a third of primates critically endangered or vulnerable (IUCN) all spp listed appendix 2, 50 appendix 1.

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guenons and drill

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Endangered primates such as guenons and drill hunted at levels that exceed sustainable levels due to their large body size, ease of transport and profitability per animal.

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farmers and primates

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farmer encroaches on forest habitats, primates feed on crops, causing farmers economic losses- gives negative impression of primates.

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Madagascar

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home to five endemic primate families. 8 classes and 15 larger spp of primates extinct since human occupation, hunting and destruction of habitat, among primates wiped out

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fragmentation

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83% of forest <100ha in Brazil. Large tracts of forest rare. Increases amount of forest vulnerable to edge effects such as farmland encroachment, lower levels of humidity and change in plant life. Movement restriction= inbreeding.

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how many of primate spp threatened

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48%

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(Johns 1986)

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Nutritious fruits more readily available in unlogged forest affecting distribution of many primates. Primate vulnerability to logging thought to be related to their “arborealness”: semi-terrestrial spp such as orang-utan fare better in secondary forest, although this exposes them to hunting, particularly when they raid crops adjacent to logged forest.

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fragmentation: 3 facets

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reduction in habitat, isolation, edge effects. RF of southern Gabon, Central Africa, spp richness and often abundance of nocturnal primates, depressed within 30m of roads, independently of hunting pressure. Forest paths affect behaviour of mammals if regularly used.

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logging

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disjointed canopy, impede movement and access for canopy spp such as gibbons. Reduced no of larger trees may deplete nesting sites. Fruit spp believed to exert strong control over densities of frugivorous mammals, any change in abundance following logging- dramatic impact.

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Hoolock gibbon

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prefer pristine forests with contiguous canopy- hard time living in secondary forests and discontinuity- major problem (Osterberg 2007)

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Johns (1987)

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degree of frugivory- negative correlation with survival ability. Body size and frugivory together explain 44% of variation in species reponses to moderate habitat disturbance. Due to selective elimination of imp food sources. Saguinus spp which eats both fruit and insects can survive well in logged areas, may increase in density as much as ten fold. Generalist feeders do dwell, some Calliecebus spp prefer secondary forest or crop mosaic. Many old world primate spp- sharp declines in pop density after logging (common chimp) whereas folivores decline in less or increase (western gorilla). Birth rates in some spp declined in logged forests- changes in social and behavioural patterns. Effects on wildlife may remain undetected for many years after logging.

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Singh 2001

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38 primate spp examined for responses to logging, 71% decline in numbers, 22% increased, 7% no change. Primate spp with ltd geographic range more likely to be affected. Lion tailed macaque only found in climax RF. Spent more time on the ground due to fragmentation- increases its vulnerability to predators, also run down by vehicles whilst crossing road. Encounters with humans increased= increased stress. Loss of canopy contiguity- increased rate of falling from trees. Unevenly distributed food resources and consequent amount of time spent in specific places= further vulnerable to predators. Non-native/ pioneer plants unpredictable productivity of food. Spp has ltd range, selective habitat, delayed sexual maturity, long interbirth interval and low pop turnover.