Quantifying Habitat and Apple Snail (pomacea Paludosa) Density Effects on Prey Availability to Snail Kites (rostrhamus Sociabilis Plumbeus) PDF Download

Author: Philip Michael Coppola
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ISBN:
Category :
Languages : en
Pages : 89

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ABSTRACT: Everglades restoration efforts rely on quantitative data when modelling the effects of management on endangered wildlife populations. The focus of this study was to quantify the influence of environmental factors on Florida apple snail (Pomacea paludosa) availability to snail kites (Rostrhamus sociabilis plumbeus) within the Everglades. A mesocosm study with observations of live apple snails was performed within Everglades wetlands to determine the influence of water depth, water temperature, dissolved oxygen, and emergent vegetation structure on the proportion of apple snails available to foraging snail kites. In addition, a study analyzing snail kite prey species (native P. paludosa versus exotic P. maculata) and size preference was performed. The proportion of apple snails available to kites was most influenced by water depth and temperature, where warm, shallow water contained the highest proportion of snails available. Emergent vegetation did not affect snail surfacing behavior; however, it did influence the relative detectability of snails. Snail kites preferentially consumed intermediate-sized snails and showed no species preference. This study supports the recommendation that demographic modeling of Everglades-dependent wildlife should incorporate the most ecologically-pertinent parameters. Estimates of snail availability can be used to link two thus far-independent simulation models for snail kite and apple snail populations.

Author: Bethany Rose Wight
Publisher:
ISBN:
Category : Everglade kite
Languages : en
Pages : 274

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ABSTRACT: Everglades restoration efforts focus on improving habitats that support associated endangered wildlife. This study focused on the influence of habitat structure and prey density on the endangered Florida snail kite and the kite's exclusive prey, the Florida apple snail. Snail densities and egg production were estimated across a habitat gradient, from the sawgrass ecotone to wet prairie habitat. Kite foraging was examined as a function of habitat and snail densities at varying spatial scales. Snail densities were relatively low, which may be attributed to a depensation effect and the distribution of snails among habitat types within a site was highly variable. Egg densities were greater along the sawgrass ecotone; however, egg abundance in wet prairie contributed more to total egg production. Kite foraging data suggested prey density variation in small patches within a site was not a good predictor of where kites concentrated their foraging. However, as scale increased (sites within a wetland, and between wetlands), snail density may explain kite occupancy. These results support the idea that restoration efforts should focus on creating habitats with a range of characteristics (sawgrass, wet prairie, and slough habitats) at varying temporal and spatial scales to support kite foraging and apple snail populations.

Author: Lara Kristen Drizd
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Category :
Languages : en
Pages :

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ABSTRACT: The apple snails of Florida, both native (Pomacea paludosa) and exotic (Pomacea insularum), have proven to be important prey items for the endangered Everglade snail kite (Rostrhamus sociabilis plumbeus) that relies on them nearly exclusively for food. Although native snail populations have diminished in recent years throughout the kites' range, the availability of the exotics has offered a temporary source of sustenance for these otherwise extreme dietary specialists. The majority of remaining kites are thought to inhabit one area, over 20 lakes that comprise the Kissimmee Chain of Lakes in central Florida. Researchers have suggested that the adult kites may be attracted to this area because of the abundance of large exotics which are known to utilize hydrilla (Hydrilla verticillata), an invasive submerged aquatic plant that dominates throughout many of the lakes. In this study, several areas of Lake Jackson were randomly selected and both species of snail were trapped as part of a mark-recapture study to determine the effects of herbicide treatments on snail movement, abundance, and density. Average snail movement rates were used to determine the effective trapping area, and the superpopulation approach was used to estimate snail abundance within each area.

Author: Kyle E. Pias
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ISBN:
Category :
Languages : en
Pages : 91

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In the Unites States the snail kite (Rostrhamus sociabilis plumbeus) is a federally endangered species whose population in Florida has undergone recent declines. The remaining population is heavily dependent upon the Kissimmee Chain of Lakes in central-Florida, particularly Lake Tohopekaliga (Lake Toho). This study will focus on how breeding snail kites use the lakeshore of habitat Lake Toho for foraging. I studied foraging behavior of breeding snail kites on Lake Toho by conducting observations on radio-tagged snail kites. I calculated 90% kernel home ranges using a kernel density estimator and quantified foraging habitat within the home ranges. Snail kite foraging behaviors were compared between foraging substrate communities to make inferences regarding the availability of snails in each community type. The patterns of foraging substrate use were also examined in regards to lake levels and time. My results indicate that foraging substrates that occur off the main body of Lake Toho may have higher snail availabilities, but that snail kite nests built in off-lake areas may be more vulnerable to predation. Therefore, in spite of relatively lower snail availabilities, foraging substrates that occur on Lake Toho may be more valuable to snail kites than off-lake areas. The availability of snails in on-lake foraging substrates is likely driven in part by water levels, highlighting the role of water management in maintaining foraging habitat for breeding snail kites.

Author: Christopher Cattau
Publisher:
ISBN:
Category :
Languages : en
Pages :

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In fact, we found that adult kites are attracted to Lake Tohopekaliga and that the relative contribution of the lake to the range-wide nesting effort increased from 6% to 33% after the invasion of the exotic snail. Conversely, the effects of the exotic snail on juvenile foraging behavior can lead to insufficient daily energy balances and may suppress juvenile survival. Given the critically endangered status of the snail kite and the propensity of the exotic apple snail to spread, this work suggests that serious management and conservation initiatives that address the exotic apple snail may be necessary to prevent further deleterious consequences for the kite population in Florida.

Author: Shannon Ladd
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Category :
Languages : en
Pages :

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ABSTRACT: The purpose of this thesis is to determine the factors that contributed to the decline of Florida apple snail (Pomacea paludosa) populations in the A.R.M. Loxahatchee National Wildlife Refuge with the goal of devising management recommendations to the Refuge regarding population management strategies. The factors examined that could have potentially contributed to population decline include the use of copper-based herbicides, insecticide application, the occurrence of drought, the use of other herbicides, the occurrence of fire, and non-avian predation. Annual Narrative documents produced by Refuge managers and staff members, dated from 1951 to 2007, were used to collect historical data for these factors. The quality of data reporting within the Annual Narratives was also examined. To support data on droughts documented in the Annual Narratives, surface water and rainfall data were obtained and analyzed. The methodology includes the use of conceptual ecological models and historical ecology to determine whether or not the factors examined produced an ecological effect capable of affecting the Refuge population of apple snails. Evidence from the Annual Narratives suggests that the use of copper-based herbicides, the occurrence of drought, and predation by alligators were responsible for the decline of the apple snail on the Refuge. A lack of consistently reported data regarding apple snail densities makes it difficult to determine the degree to which each factor had an effect on the apple snails or to determine if any spatio-temporal relationship existed between the Florida apple snail and Everglade snail kite (Rostrhamus sociabilis plumbeus) based on copper-based herbicide use. The overall quality of the Annual Narratives improved throughout the study period and eventually focused heavily on investigative studies. Several management recommendations were suggested to improve Florida apple snail populations on the Refuge. First, in order to monitor the health and trends of the apple snail population, a monitoring network needs to be established with results maintained in a geodatabase. Both apple snail density and egg cluster counts need to be made following an established sampling method. Second, in an attempt to sustain higher apple snail densities, stocking of the interior should be attempted. Finall, in the event that adjacent farmlands are to be restored, soil samples need to be analyzed to determine if concentrations are high enough that desorption of copper from the flooded agricultural soils could pose a serious threat to the Refuge by reintroducing toxic levels of copper.

Author: Laksiri Bandara Karunaratne
Publisher:
ISBN:
Category : Florida applesnail
Languages : en
Pages : 140

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Author: Christina M. Trexler
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ISBN:
Category : Competition (Biology)
Languages : en
Pages : 63

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Invasive species are detrimental to native biotas worldwide. Recently, Florida was invaded by a freshwater snail (Pomacea canaliculata) native to Argentina. This snail is a serious pest of rice crops in Asia, but little is known about its interactions within Florida ecosystems. Possible competitive exclusion of the native congener (P. paludosa) is a concern because it is the almost exclusive prey of the federally endangered Everglades snail kite (Rostrhamus sociabilis). My research consisted of three parts. First, to identify possible methods to control P. canaliculata in the egg stage, I experimentally evaluated the effects of photoperiod, substrate availability, and food type and availability on hatching success and hatchling survival. None of these factors significantly affected hatching or survival, suggesting that P. canaliculata could invade many water bodies. Second, I used a randomized block design to assess the separate and combined effects of population density and food availability on growth and spawning of P. canaliculata. Food availability but not density significantly affected growth; snails fed less food grew less, but neither factor affected spawning. Third, I used a replacement series design to assess competition between P. canaliculata and P. paludosa under food limitation. For both species, snails fed less grew significantly less, and snails exposed to greater congener densities spawned less than when exposed to conspecifics only. While my results predict that P. paludosa should exclude P. canaliculata, previous literature and current invasions suggest that the exotic snail may co-exist with its North American congener.

Author:
Publisher:
ISBN:
Category : Florida applesnail
Languages : en
Pages : 176

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This report documents a study to determine the survival of the Florida apple snail as a critical food web component in Florida wetlands in consideration of restoration efforts ongoing in central and south Florida.

Author: Matthew C. Perry
Publisher:
ISBN:
Category : Everglade kite
Languages : en
Pages : 12

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