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Observer error in citizen ornithologyFarmer, Robert Gordon 02 August 2012 (has links)
Citizen science, which uses volunteer observers in research, is fast becoming standard practice in ecology. In this thesis, I begin with an essay reviewing the benefits and limitations of citizen science, and then measure the influence of several forms of observer error that might bias ornithological citizen science. Using an internet-based survey, I first found that observer skill level can predict the nature of false-positive detections, where self-identified experts tend to falsely detect more rare species and moderately-skilled observers tend to falsely detect more common species. I also found that overconfidence is widespread among all skill levels, and hence that observer confidence is an unreliable indication of data quality. Using existing North American databases, I then found that older observers tend to detect fewer birds than younger observers -- especially if the birds' peak call frequencies exceed 6 kHz -- and that published long-term population trend estimates and high-pitched (>= 6 kHz) peak bird vocalization frequencies are negatively correlated. Taken together, these data suggest that both hearing loss and other sensory changes might be negatively biasing long-term trend estimates. In the next chapter, I measured how observer experience can bias detection data. In solitary observers, I found that detections tend to increase over the first 5 years of service (e.g. learning effects), after which they decline consistently (e.g. observer senescence). Conversely, among survey groups that may be motivated to exceed a previous year's species count, I found that species richness tends to increase consistently with consecutive survey years. In this case, individual sensory deficits may be offset by group participation. Lastly, I re-evaluated the established assumption that the quality of new volunteers on North American Breeding Bird Survey routes is increasing over time. I showed that the existing measure of “quality” ignores variable lengths of observer service, and that, after accounting for this variable, “quality” is unchanging. Throughout this thesis, I also show how generalized additive mixed models can address these biases statistically. My findings offer new opportunities to improve the accuracy and relevance of citizen science, and by extension, the effectiveness of wildlife conservation and management.
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Gray wolves (canis lupus) movement patterns in Manitoba : implications for wolf management plansScurrah, Fiona Elizabeth 20 February 2013 (has links)
In 2010 and 2011, Manitoba Hydro in collaboration with Manitoba Conservation collared 65 gray wolves (Canis lupus) as part of a larger multi-year boreal woodland caribou research project. There is insufficient data regarding populations of gray wolves in Manitoba or their movements throughout the province. The objective of this study was to typify wolf movements in Manitoba to provide recommendations for industry and government for the development of policy and integrated resource management plans of this species. Of the 65-collared wolves, 11 were selected to examine their movements in three regions of the Province. It was found that wolf populations overlap one another in the study area, to varying degrees. Their ability to move long distances, creates challenges for resource managers, as most management plans only consider management at a regional scale rather than a multi-jurisdictional level. In addition, this examination of gray wolf movements will assist in understanding their role as predators on the protected boreal woodland caribou and depressed moose populations within the Province.
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Environmental stochasticity and African elephant population dynamics : investigating limitation through juvenile mortality.January 2008 (has links)
The successful conservation management of African elephants depends largely on understanding the fundamental processes driving the population regulation of this species. Southern Africa’s increasing populations have raised concern over the impact of high elephant densities on the system, in stark contrast against the elephant’s more precarious position in other parts of Africa. As we search for solutions from the processes of historical elephant regulation, we realise that there is a decided lack of empirical evidence to explicitly direct our efforts. In this PhD, I attempt to investigate the application of the classic pattern of large herbivore population limitation, which mainly involves high juvenile mortality in response to stochastic environmental events, to African elephant population dynamics. Firstly, I evaluated the magnitude and frequency of mortality events that would be required to prevent elephant population growth. The death of 85 % of infants and weaned calves would need to occur twice a generation, while a single severe mortality event (causing the death of all infants and weaned calves and 10 % of the rest of the population) once a generation would be sufficient. However, the severity of these events is not matched in natural occurrence in Africa today and only a single recorded event in Tsavo National Park, Kenya, in the 1970’s has come close when more than 7 000 died during a very severe drought. Secondly, I evaluated the potential role of fire as a stochastic, massmortality event limiting elephant populations. I found that fire functions in a similar manner to other environmental catastrophes and primarily causes high juvenile mortality. However, this catastrophic event also highlighted the extreme behavioural and physiological impacts experienced by the elephant population involved. The potential role of these types of events on long-term female fecundity needs further investigation. In isolation, this type of mortality event would need to occur with high frequency to prevent population growth. However, in combination with a decrease in female fecundity, these stochastic events may have a much greater impact on population demography than first thought. Thirdly, I investigated a potential mechanistic link between stochastic mortality events and juvenile susceptibility to resource limitation. Allometric relationships dictate that juveniles select a diet of higher quality than adult elephants. We found that this was achieved by weaned calf selection of higher quality plant parts, although use of plant types and plant species was similar to that of adult females, who they move across the landscape with. The strong sexual dimorphism exhibited by this species was reflected in adult male use of lower quality forage than adult females (or juveniles) in both dry and wet seasons. Diet quality scaled negatively with body size, but adult females consistently selected a higher quality diet than adult males, irrespective of body size. The nutritional and reproductive demands placed on an individual during different life-history stages therefore influence foraging strategies, together with nutrient requirements, e.g. phosphorus for pregnancy/lactation selected consistently by females when unrestricted in the wet season, protein for growth selected consistently by weaned calves. Competitive displacement of adult females to feed at higher levels in the canopy by calves also influenced feeding behaviour. Therefore intraspecific body size, nutritional requirements (in terms of nutrients and energy) and competition had a strong influence on foraging strategy employed by age-sex classes of elephants in response to seasonal environmental change. More selective juvenile foraging requirements means that juveniles are most susceptible to resource limitation, for example during stochastic environmental events such as droughts. In small, closed systems, juvenile mortality is likely to have a strong influence on elephant population regulation, with a slight, temporary decrease in female fecundity possibly acting in conjunction with juvenile mortality effects. Therefore, stochastic environmental events such as drought and fire may be the only natural incidence of population regulation to occur in these systems, where populations continue to grow exponentially and there is no evidence of density-dependence (as in the case of many small, fenced reserves in South Africa). In large, open, high-density systems in other parts of southern Africa, density dependence acts strongly on female fecundity and causes low levels of juvenile mortality in areas of local population aggregation. Therefore, in isolation, natural juvenile mortality is unlikely to regulate African elephant populations, but in conjunction with decreased female fecundity in response to density-dependent feedbacks and stochastic environmental events, population regulation may occur. The management of long-lived megaherbivore species with similar demographic drivers must include an appreciation of the complexity of population response to manipulation of mortality or fecundity effects. Small changes can potentially result in large shifts in population dynamics. Further insight into the mechanisms driving these processes will allow sound scientific support of megaherbivore management decisions to be made throughout Africa. / Thesis (Ph.D.)-University of KwaZulu-Natal, Westville, 2008.
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Modelling the effect of property size on the opportunity cost incurred by wildlife production.Tomlinson, Kyle Warwick. January 1998 (has links)
It is claimed that high returns can be achieved from hunting and ecotourism operations. As a result wildlife production is a rapidly growing form of land-use in South Africa. Lately, rural African communities have approached regional conservation agencies for aid to establish small game reserves so that they too may benefit from wildlife production. However wildlife
operations have high input costs relative to domestic stock operations and no attempt has been made to determine the effect of property size on the costs and revenue generated by wildlife. It is thus necessary to conduct a Cost-Benefits Analysis to ascertain this effect by determining the opportunity cost incurred by choosing wildlife over other land-uses suitable in semi-arid savannas, namely communal subsistence production and commercial beef production. This project attempts to quantify the revenue generated, and the variable costs and fixed costs incurred by wildlife production, subsistence production and commercial beef production in
order to observe their behaviour against property size and by this means to establish the size ranges for which each of the three land-uses is most appropriate. Mathematical modelling is used to define each of the three land-uses and how their revenue and cost curves interact with property size. The resultant profit curves are able to assess only the financial benefits from each of the land-uses to the local community. An assessment of the full economic benefits to the local and broader community would require different criteria and apportionment of costs and revenue.
The effect of property size on fixed costs is the single most important factor which distinguishes the behaviour of the profit curves of the three land-use options: subsistence production has negligible fixed cost input and so is able to achieve greater profitability than either beef or wildlife at small property sizes. Beef has high input costs per hectare at small land sizes which diminish with each unit of additional land. Wildlife operations also have high input costs at small land-sizes which decrease per hectare with additional land added. However due to the service industry nature of wild life operations, fixed costs increase per hectare after some point
(in this case it is assumed to be 2000 ha). This is because the attractiveness of game reserves to tourists increases with size due to the inclusion of "many" species of game, which in turn increases the number of people entering the park per hectare and as such the fixed cost input
required to accommodate those extra people. The specific results derived from the model indicate that the profit curve of wildlife rises far
more steeply than those of either subsistence production or commercial beef production. However, due to the effect of input costs, both commercial beef and subsistence production are more profitable at land sizes of less than 3000 ha. This indicates that investing large sums of money into small game reserves of less than 3000 ha may not be justified on the basis of profits alone. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 1998.
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Resource overlap within a guild of browsing ungulates in a South African savanna.Breebaart, Lorene. 19 December 2013 (has links)
Food selection by free-ranging black rhinoceros, eland, giraffe and kudu as well as the utilisation
of vegetation types by the latter three browsers were investigated over an entire seasonal cycle,
from June 1998 to July 1999, at Weenen Nature Reserve, KwaZulu-Natal. The study was aimed
at determining the extent of resource overlap within this browser guild. Feeding habits of eland,
giraffe and kudu were studied by direct observations, while a plant-based technique was used
for black rhinoceros. Dung counts were conducted to monitor selection for vegetation types.
Overlap was estimated by measuring the similarities in resource utilisation patterns.
Giraffe were exclusively browsers, feeding mostly on woody foliage, over the complete seasonal
cycle. The bulk of the annual diet of kudu also consisted of woody browse, although forbs were
important and their use increased from early summer to winter. The annual diet of eland
consisted of approximately equal proportions of grass and browse, with pods making up almost
a third of the diet. Similar to kudu, forbs were more prominent in the winter diet, while grass use
decreased. During winter, overlap in forage types generally increased and was considerable
because the browsers did not resort to distinct forage 'refuges'. Overlap in the utilisation of
woody plant species, however, decreased as animals diversified their diets. Nonetheless, overlap
was extensive, primarily owing to the mutual utilisation of Acacia karroo and Acacia nilotica.
The quantity of woody foliage decreased during winter, as indicated by phenological differences,
but numerous individual plants still carried leaves. Based on current evidence, food quality was
assumed to decline. Under prevailing conditions, eland, giraffe and black rhinoceros suffered
no mortalities indicating that they were not food limited, possibly owing to the nutritional
advantages conferred by their large body size, and that competition among them was unlikely.
By comparison, kudu mortalities were great which may signify that they were constrained by
food supply and that the larger browsers exerted a pronounced competitive effect on them.
Based on the current study it is hypothesised that during periods of resource scarcity the
abundance of high quality foods are limited and if interspecific competition does prevail, which
will further limit the availability of these resources, it is the smaller bodied herbivores that will
be most affected and suffer the greatest mortalities. Consequences of competitive interactions
among these browsers have important management implications, especially in small reserves,
which are a key stone for the conservation of mammalian herbivores. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2000.
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A LONG-TERM INVESTIGATION OF THE FEDERALLY THREATENED DESERT TORTOISE (<em>GOPHERUS AGASSIZII</em>) AT A WIND ENERGY FACILITY IN SOUTHERN CALIFORNIAAgha, Mirza Mickey 01 January 2015 (has links)
With the recent increase in utility-scale wind energy development and current climate variation in the desert southwest US, researchers have become increasingly concerned with the reaction of wildlife and critical habitat. Understanding the relationships among monitoring efforts, climate, industrial landscapes and wildlife is critical to effective management. Given the need for information available on how these potential stressors affect terrestrial wildlife, my objective was to determine how climate variation, wind energy facilities (WEF) and monitoring efforts by researchers influence behavior and survivorship in a population of the federally threatened desert tortoise (Gopherus agassizii). Data were collected via surveys, motion-sensor camera trapping and radio-telemetry during the span of two decades at a WEF in California. Using capture-mark-recapture survivorship analysis and generalized linear mixed-effects models, I acquired long-term estimates of survivorship, activity, and levels of stress response to researchers and climate. From this study I found that researchers as well as abiotic effects influence the probability of voiding, a possible stress induced behavior in desert tortoises. Additionally, we found that tortoise activity and survival is constrained by winter precipitation and habitat types. Further research is needed on proximate mechanisms of wind turbines (noise and vibration) and their effects on desert tortoise behavior.
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A meta-analysis of the value of marine protected areas for pelagic apex predatorsDunphy-Daly, Meagan January 2015 (has links)
<p>A vast range of theoretical and empirical studies now suggests that MPAs can conserve marine biodiversity and, under some circumstances, increase fishery yields. However, despite the importance of pelagic apex predators to ecosystem function, the effectiveness of spatial management for the conservation of pelagic apex predator species is still unknown. I used fishery-dependent logbook and observer datasets to assess fishing effort and both the catch and size of pelagic apex predator species around five different MPAs. The US Hawaii-based deep-set or Atlantic pelagic longline fisheries fish the waters around these MPAs; both of these fisheries have experienced multiple management measures over time to protect species and maximize fishery yield. The MPAs selected for this study range in size, age, level of protection, and reason for establishment. I found that only two MPAs of the five appeared to be benefitting the pelagic apex predator species that I selected: the DeSoto Canyon and East Florida Coast MPAs, both in the Atlantic Ocean. The size of yellowfin tuna around the DeSoto Canyon MPA borders has increased over time, as has fishing effort. In contrast, the size of swordfish has decreased near the boundary of the East Florida Coast MPA, although the catch of swordfish has increased. The increase in catch of smaller swordfish was not a surprise because the East Florida Coast MPA was established around an area that is a nursery habitat for swordfish. These results are promising for the use of static MPAs for the conservation of pelagic apex predators, but three of the MPAs in my study did not show any indication of increased fishing effort, increased catch, or changes in pelagic apex predator size near their boundaries over time. Therefore, the characteristics of the DeSoto Canyon and East Florida Coast MPAs may provide a template for how to best design new MPAs for pelagic apex predators. Both of these MPAs were established with the specific intent of reducing pelagic apex predator bycatch, in areas where there were historically high catch rates. Both areas are relatively large (> 85,000 km2) and are also closed year-round. In combination, these characteristics may provide protection for pelagic apex predators.</p> / Dissertation
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African Elephant (Loxodonta Africana) Conservation in TanzaniaJacobs, Zoe M 01 January 2015 (has links)
Increasing human population and development in Africa restricts land and resources for African elephants (Loxodonta africana) and threatens the preservation of the species. Despite the importance of conservation for many governments in Africa, many local communities have negative views of elephants and exhibit anti-conservation behavior. By looking at the history of wildlife policy in Tanzania, this paper seeks to understand these opinions through a historical context. Three case studies of conservation initiatives were evaluated to determine what aspects of conservation initiatives promote long-term pro-conservation behavior on the part of the local community. Ultimately, conservation initiatives should establish a framework whereby local communities are empowered through conservation.
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The feeding and behavioral ecology of black spider monkey subgroups (Ateles paniscus paniscus) in the context of illegal artisinal goldmining activities in the Brownsberg Nature Park, SurinameVreedzaam, Arioene Uncas Naldi 13 June 2014 (has links)
<p> The Brownsberg Nature Park (BNP) in Suriname is home to eight monkey species: <i>Saguinus midas, Saimiri sciureus, Cebus apella, Alouatta seniculus. Pithecia pithecia, Cebus olivaceus, Chiropotes satanas (sagulatus), </i>and <i>Ateles paniscus.</i> Several studies have undertaken the task to better study the feeding and behavioral ecology of these species within the park. However, studies on the black spider monkey (<i>Ateles paniscus</i>) have been absent. As part of my thesis, I decided to conduct a baseline feeding and behavioral ecology study of this species during the period May 2008 – July 2008. In addition, I developed a field method for determining mercury levels (in parts per million = ppm) in fecal and urine samples of wild monkeys. Since the park is under enormous pressure from illegal gold mining activities, I decided to collect baseline data on potential exposure of wild monkeys to mercury in the environment. I also collected samples from monkeys at the zoo in Paramaribo and monkeys born in captivity at Hiram College in Ohio. I collected data on the frequency of feeding, resting, and traveling by black spider monkey subgroups every 10 minutes during all day follows. Feeding ecology data consisted of identifying fruits eaten by these subgroups. For the mercury analysis I used the OSUMEX LTD. home testing kit. Results from the behavioral data show the following frequencies of activities for the entire study period: 32% feeding, 43% resting, and 25% traveling. The feeding data further justifies spider monkeys as ripe fruit frugivores: 76% of food items consisted of ripe fruit, while 22% consisted of leaves, and 2% was comprised of flowers. The mercury testing results from the Brownsberg and zoo populations ranged between 0.025 ppm to 0.1 ppm (toxic level = 0.8 ppm). The Hiram College monkeys all displayed levels at 0.000 ppm. The results from the mercury analyses indicate that 1) wild monkeys in the vicinity of gold mining activities may not be under the same threat as humans, with regards to mercury exposure through food, and 2) that wild monkeys are still relative exposed to mercury in the environment whether it be natural or anthropogenic.</p>
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Seasonal movements, diet composition, and diet nutritional quality of Unimak Island caribouLegner, Kate A. 18 June 2014 (has links)
<p> The Unimak Island caribou herd is in the midst of a population decline associated with low birth rates and calf survival. I evaluated the spatial and temporal complexity of caribou landscape use and the availability and nutritional quality of key forage species. First, I examined seasonal landscape use and movement using GPS collar data. Second, I determined seasonal diets to the species-level for spring, summer, and fall using a novel n-alkane and long-chain fatty acid (LCOH) method. Finally, I compared diet quality with needs for maintenance and to the quality of available plant species. Caribou home ranges were largest and movements least in the winter, and movements appeared dependent on plant phenology and weather conditions. Diets were complex and seasonally variable but generally contained higher proportions of forbs than other caribou herds likely due to their higher relative availability as compared to other preferred forages. Finally, animals foraged selectively each season, obtaining a diet that was higher in digestible dry matter and nitrogen than the average of plants available. Nutritional quality appeared to be well above requirements during the three seasons investigated. Overall, I concluded that spring, summer, and fall forage quality and availability do not impose strong constraints on Unimak Island caribou. However, I recommend that diet composition and quality be determined in the winter, the time when forage often limits the productivity of caribou herds.</p>
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