The anthropogenic use of natural resources has become a major cause of biodiversity loss and habitat degradation throughout the world. Deforestation - the conversion of forests to alternative land covers - has led to a decrease in local biodiversity directly through a decrease in habitat, and indirectly through habitat fragmentation. Likewise, defaunation – the loss of animals both directly through hunting and indirectly through deforestation – has led to the empty forest syndrome and subsequent deterioration of forest ecosystems. In many cases, areas where anthropogenic use of natural resources is high overlap with areas of high biodiversity value. Therefore, the present series of studies aims to better understand the impacts that different types of natural resources use and habitat degradation have on biodiversity. This dissertation details the results of five studies, which aimed to: 1) examine the effects of habitat degradation on plant-frugivore networks; 2), understand the live capture and extent of ownership of lemurs in Madagascar; 3) understand the micro- and macro-level drivers of wild meat consumption in Madagascar; 4) describe the capture, movement, and trade of wild meat in Madagascar; and 5) the impacts of habitat changes on the diets and vertical stratification of frugivorous bats.
For the first study, our objectives were to understand the effects of habitat degradation on (1) community structure, (2) network structure, and (3) seed dispersal services. We focused on fruit-bearing trees and frugivores (two lemur and five bird species) across a three-point gradient of habitat degradation in a tropical dry forest in Madagascar. Our objectives were to understand the effects of habitat degradation on (1) community structure, (2) network structure, and (3) seed dispersal services. We focused on fruit-bearing trees and frugivores (two lemur and five bird species) across a three- point gradient of habitat degradation in a tropical dry forest in Madagascar. Data on fruit consumption by frugivores were collected over 592 hours of observations at 13 fruiting tree species. We found that as habitat became more degraded: (1) the community structure of both frugivores and fruiting tree communities changed; (2) the mutualistic network structure became less complex and less connected; (3) the interaction strengths of pair-wise interactions changed and the asymmetries of these interactions shifted; and (4) seed dispersal decreased by 91% in the secondary forest, compared to the primary forest. In addition, we show that frugivores: (1) sometimes stopped eating fruit in the degraded forest, even when they had consumed it in other forests; and (2) appeared to avoid some fruiting tree species while showing preference for others. The mutualistic network studied in this paper appeared sensitive to anthropogenic disturbance and a novel measure of effectiveness helped quantify these changes.
For the second study, our objectives were to provide the first quantitative estimates of the prevalence, spatial extent, correlates and timing of lemur ownership, procurement methods, within-country movements, and numbers and duration of ownership. Using semi-structured interviews of 1,093 households and 61 transporters, across 17 study sites, we found that lemur ownership was widespread and affected a variety of taxa. We estimate that 28,253 lemurs have been affected since 2010. Most lemurs were caught by owners and kept for either short (≤1 week) or long (≥3 years) periods. The live capture of lemurs in Madagascar is not highly organized but may threaten several endangered species.
For the third study, we investigated the role of wild meat in food security in Madagascar, a country where wild meat consumption is poorly understood in urban areas and at regional scales. Using semi-structured interviews (n = 1339 heads-of-households, 21 towns), we aimed to: 1) quantify the amount and purpose of; 2) understand the drivers behind; and, 3) examine recent changes in wild meat consumption in Madagascar. Few respondents preferred wild meat (8 ± 3%) but most had eaten it at least once (78 ± 7%), and consumption occurred across ethnic groups, in urban and rural settings. More food insecure areas reported higher rates of recent consumption of wild meat. However, consumption was best explained by individual preferences and taboos. Few respondents (<1 ± <1%) had increased rates of consumption during their lifetimes, and wild meat prices showed no change from 2005-2013. Most consumption involved wild pigs and small-bodied animals, though these animal groups and lemurs were consumed less in recent years. Given these data, wild meat is unlikely to enhance food security for most Malagasy people in urban and well-connected rural areas.
For the fourth study, and to improve understanding of the wild meat trade in Madagascar, our objectives were to: (1) quantify the volume of consumption, transport, and sale for different animal groups, compared to domestic meat; (2) describe the methods of capture and hunting for different animal groups; (3) analyze the patterns of movement of wild meat from the capture location to the final consumer, compared to domestic meat; and (4) examine how the prices of wild meat change depending on the venue through which the consumer purchases it. Data was collected in May-August 2013 using semi-structured interviews of consumers (n = 1343 households, 21 towns), meatsellers (n = 520 restaurants, open-air markets stalls, and supermarkets, 9 towns), and drivers of inter-city transit vehicles (n = 61, 5 towns). We found that: (1) a wide range of hunting methods were used, though their prevalence of use differed by animal group; (2) wild meat traveled distances of up to 166 km to reach consumers, though some animal groups were hunted locally (<10 km) in rural areas; (3) most wild meat was procured from free sources (hunting and receiving meat as a gift), though urban respondents who consumed bats and wild pigs were more likely to purchase those meats; and (4) wild meat was consumed at lower rates than domestic meat, though urban respondents consumed twice as much wild meat as rural respondents. We conclude that urban and rural respondents differ in how they interact with the wild meat commodity chain. We also believe that the consumption and trade of wild meat in Madagascar is likely more formalized that previously thought.
Finally, for our fifth study, we used stable isotope analysis to examine how foraging by three fruit bat species in Madagascar, Pteropus rufus, Eidolon dupreanum, and Rousettus madagascariensis, are impacted by habitat change across a large spatial scale. Our results indicated that the three species had broadly overlapping diets. Differences in diet were nonetheless detectable and consistent between P. rufus and E. dupreanum, and these diets shifted when they co-occurred, suggesting resource partitioning across habitats and vertical strata within the canopy to avoid competition. Changes in diet were also correlated with a decrease in forest cover, though at a larger spatial scale in P. rufus than in E. dupreanum. These results suggest fruit bat species exhibit differing foraging strategies in response to habitat change. They also highlight the key threats that fruit bats face from habitat change, and clarify the spatial scales at which conservation efforts should be implemented to mitigate threats for these bat species in Madagascar.