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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
271

Tidal Cycle Effects on the Occurrence of the Florida Manatee (Trichechus manatus latirostris) at the Port Everglades Power Plant

Rappucci, Gina 19 October 2009 (has links)
The seasonal distribution of the Florida manatee (Trichechus manatus latirostris) is influenced predominantly by feeding locations in the summer and proximity to warm-water refuges during colder months. Due to their limited ability to tolerate cold water, when water temperatures drop below 20°C manatees congregate around natural and artificial warm-water refuges, such as warm-water springs or power plant outfalls. Distribution may further be influenced by the tidal cycle through its impact on manatee movement and foraging. Although the importance of tide on manatee distribution and habitat selection has been acknowledged, it has yet to be studied quantitatively in respect to the manatee population in southeast Florida. The purpose of this study was to examine the effect of the tidal cycle on manatee occurrence at the Florida Power & Light (FPL) Port Everglades Power Plant. Walking surveys were conducted in Port Everglades during manatee season, November 15 – March 31, between 2004 and 2008. During the surveys, the number of manatees in four established locations was noted and the animals categorized based on size as either calf, juvenile, or adult. Water temperature data were also collected at four permanent sample locations. Because many surveys yielded zero manatees observed, data were analyzed using the zero-inflated negative binomial model. Although the manatees at the Port Everglades Power Plant must forage away from the warm-water refuge, my findings show no correlation between tidal state and total manatee occurrence at the FPL Port Everglades Power Plant. The results do, however, suggest that the probability of observing a cow/calf pair is greater during high tide when compared to low and mid-tides (P < 0.05). Total manatee occurrence and the presence of cow/calf pairs were both significantly correlated with water temperature (P < 0.05).
272

Space use and habitat selection of the wolf (<em>Canis lupus</em>) in human-altered environment in Finland

Kaartinen, S. (Salla) 23 March 2011 (has links)
Abstract The grey wolf is the most widely distributed of all land mammals and is a habitat generalist that inhabits all the vegetation types of the Northern Hemisphere. Wolves also breed well and have the potential to rapidly expand to new areas. In Finland, the wolf is a game species, and as a result of Finland’s membership of the European Union, the wolf population is subject to very limited hunting due to the obligation to protect the species. Mainly for this reason, the wolf population in Finland has increased significantly in recent years. In particular, the birth rate has developed favourably and the number of litters increased from just four in 1996 to 20 in 2005. It also seems at present that the wolf population in Finland is no longer following the fluctuations in wolf numbers in Russian Karelia. The general aim of this dissertation is to provide applicable knowledge for wolf management and conservation purposes, and especially to examine the effects of human-modified landscapes on wolf population expansion in Finland. Various aspects of habitat selection were investigated in four sub-studies to gain a thorough insight into the space use and habitat needs of wolves. Species data came from a long-term wolf population study that included location information from 85 radio- and GPS-GSM-collared wolves from 1998 onwards, as well as track location data based on about 30 000 annual observations recorded with geographical coordinates by a local network of experts on large carnivores. I found that adaptability makes it possible for the wolf to live in the multiple-use, semi-wild forests of Finland and that no restrictions are imposed by the landscape on wolf population growth and expansion. In general, the results of my dissertation provide evidence that wolves tend to avoid the presence of human influence when establishing a territory and also when selecting their den site. However, as wolf numbers increase, conflict situations will more frequently occur between wolves and humans, although the risk of depredation events, for example among sheep farms, varies between farms in Finland. That is, there are some environmental and farm level factors that are associated with wolf depredation. The breeding wolf population in Finland has gradually expanded and the first litters have recently been born in western Finland after an absence of more than 100 years. The geographical distance to the Scandinavian population is shorter from these new western territories than from the population’s core area in eastern Finland. This could potentially increase the likelihood of dispersal from Finland to Scandinavia. / Tiivistelmä Susi on habitaattigeneralisti, jonka levinneisyys kattaa kaikki pohjoisen pallonpuoliskon kasvillisuustyypit. Sudet myös lisääntyvät hyvin ja voivat näin ollen levittäytyä nopeasti uusille alueille. Suomessa susi on riistalaji, jonka metsästys on rajoitettua Euroopan unionin jäsenyyden myötä. Lähinnä tästä syystä Suomen susikanta on kasvanut voimakkaasti 1990-luvun ja 2000-luvun alun aikana. Erityisesti syntyvyys on kasvanut: pentueiden määrä lisääntyi neljästä 20:een vuosien 1996 ja 2005 välillä. Näyttäisi siltä, ettei Suomen nykyinen susipopulaatio enää seuraa Venäjän Karjalassa tapahtuvia kannanvaihteluita. Väitöskirjan tavoitteena on ollut tuottaa susikannan hoidossa ja suojelussa käytettävissä olevaa tietoa ja erityisesti tutkia susikannan levittäytymistä ihmisen muokkaamassa ympäristössä Suomessa. Neljässä osatutkimuksessa on käsitelty suden habitaatinvalintaa eri näkökulmista, jotta saataisiin kokonaiskuva suden tilankäytöstä Suomessa. Tutkimusaineisto rakentui pitkäaikaisesta seuranta-aineistosta, jota on kerätty vuodesta 1989 lähtien. Vuosien 1989 ja 2010 välillä 85 sutta on pannoitettu radio- tai GPS-GSM –pannalla. Tutkimuksessa käytettiin hyväksi myös noin 30 000 vuosittain tehtyä jälkihavaintoa. Tutkimustulosten perusteella susi selviää hyvin Suomen monikäyttömetsissä, eivätkä maisematyypit itsestään rajoita susipopulaation kasvua ja levittäytymistä. Toisaalta tulokset osoittavat myös sen, että sudet välttelevät ihmistoimintoja valitessaan reviiri- tai pesäpaikkoja. Kuitenkin susien lukumäärän kasvaessa ristiriitatilanteet susien ja ihmisten välillä tulevat lisääntymään, vaikka susivahinkoriskin suuruus vaihteleekin Suomessa huomattavasti. Esimerkiksi lammastilojen susivahinkoriski riippuu sekä ympäristötekijöistä, että tilan sisäisistä tekijöistä. Kaiken kaikkiaan lisääntyvän susipopulaation esiintymisalue on Suomessa vähitellen kasvanut leviten itärajan tuntumasta kohti länttä. Tämän myötä maantieteellinen etäisyys Skandinavian susipopulaatioon on pienentynyt viimeisten vuosien aikana. Tämä voi edesauttaa susiyksilöiden siirtymistä Suomesta Skandinaviaan.
273

Partage au sommet de la chaîne alimentaire : comment la hyène tachetée s'adapte à la présence de lions ? : coexistence des prédateurs apicaux dans une savane arborée / Sharing the top : how do spotted hyaenas cope with lions ? : apex predator coexistence in a wooded savana

Périquet, Stéphanie 10 July 2014 (has links)
Étant au somment de la chaîne alimentaire, les grands prédateurs ont la capacité d'influencer le fonctionnement des écosystèmes, y compris au sein de leur guilde. En Afrique, les lions (Panthera leo) et les hyènes tachetées (Crocuta crocuta, hyènes ci-après) sont les plus gros et les plus nombreux prédateurs, et les hyènes sont souvent considérées comme subordonnées aux lions. Néanmoins, notre compréhension de leurs interactions est très limitée, d'autant plus dans les milieux boisés. Ce travail vise à identifier les mécanismes permettant la coexistence des hyènes et des lions. L'hypothèse principale est que les hyènes évitent les lions à la fois dans l'espace et dans le temps. Une revue de la littérature montre que malgré leur fort potentiel pour la compétition d'exploitation (régimes alimentaires similaires) et d'interférence (kleptoparasitisme et prédation), les lions partagent la quasi-totalité de leur distribution avec les hyènes et leurs densités sont positivement corrélées. J'ai collecté des données sur l'écologie des hyènes et des lions durant 2.5 ans à partir d'observations directes et de colliers GPS dans le Parc National de Hwange (PNH), au Zimbabwe. PNH est caractéristique d'une savane dystrophique arborée semi-aride dominée par l'éléphant (Loxodonta africana). L'écologie de la hyène y est largement influencée par la localisation des points d'eau artificiels, des carcasses d'éléphants et des lions. Les hyènes sélectionnent les habitats riches en proies et près des points d'eau, tout comme le font les lions qu'elles n'évitent que dans des conditions extrêmes de vulnérabilité et de risques. Les carcasses d'éléphants représentent une ressource alimentaire majeure pour les hyènes qui en ont augmenté leur utilisation en réponse à une augmentation de la compétition avec les lions. La disponibilité de ces carcasses facilite probablement la coexistence entre les deux carnivores. Les rencontres avec les lions autour de carcasses sont communes et les deux espèces peuvent rester à proximité pendant plusieurs nuits consécutives. En revanche, les rencontres non liées aux carcasses sont de très courte durée et les deux prédateurs s'éloignent rapidement l'un de l'autre. Contrairement à l'hypothèse classique, les hyènes n'évitent pas les lions de manière systématique. Les interactions entre les deux espèces sont complexes et les hyènes répondent aux lions de manière dynamique et réactive plutôt que prédictive. Bien que les lions soient leur plus grand compétiteur, les hyènes restent à proximité dans certaines circonstances, car ils représentent une source alimentaire grâce au charognage et au kleptoparasitisme. Ces résultats apportent de nouvelles connaissances sur les mécanismes de coexistence et d'interactions entre grands carnivores ainsi que sur l'impact potentiel des décisions de gestion sur leur écologie qui peuvent être utiles pour leur conservation / Being at the top of the food chain, apex predators have the potential to influence the whole community structure through food webs, even within their own guild. In Africa, lions (Panthera leo) and spotted hyaenas (Crocuta crocuta, hyaenas hereafter) are the largest and most numerous predators, with hyaenas often thought to be subordinate to the larger lion Never the less, our understanding of their interactions is limited, even more in wooded ecosystems. This work focuses on identifying the mechanisms allowing for hyaenas and lions to coexist, such as resource and habitat partitioning. The main hypothesis is that hyaenas should avoid lions both spatially and temporally. A literature review shows that despite the high potential for exploitative and interference competition (high range and diet overlaps), hyaenas are present at nearly all sites occupied by lions and their densities are positively correlated. I collected data on hyaena and lion ecology, through direct observations and GPS collars, during 2.5 years of fieldwork in Hwange National Park (HNP), Zimbabwe. HNP is characteristic of a semi-arid dystrophic wooded savanna dominated by elephants (Loxodonta africana). In HNP, hyaena ecology is largely influenced by the location of artificial waterholes, elephant carcasses and lions. Hyaenas select for habitats where prey are abundant and locations close to artificial waterholes, as do lions. Hyaenas only spatially avoid lions in extreme conditions of vulnerability and risk. Elephant carcasses are a major source of food for hyaenas and their used increased during a period of increased intraguild competition with lions, which lead to switch in hyaena foraging strategy from active hunting to scavenging. The presence of large carcasses is probably promoting coexistence between the two large carnivores. Encounters with lions at carcasses are common and can occur during several consecutives nights with the two predators staying in the vicinity of each other. However, when not related to food, encounters are very short with both predators often moving away after being in contact. In stark contrast with the classical hypothesis, hyaenas in HNP do not show a general pattern of lion avoidance. Interactions between these two species are complex and hyaenas appear to respond to lion presence is reactive rather than predictive and very dynamic. Even though lions are their main competitors, in some circumstances hyaenas stay in their vicinity, as they can also be a source of food through scavenging and kleptoparatism. These results bring some light on the mechanisms of interaction and coexistence between large carnivores as well as the impact on management decisions on their ecology that could prove useful for planning their conservation
274

Biologia e ecologia de Eustala taquara (Keyserling, 1892), (Araneae, Araneidae) na Serra do Japi, Jundiaí - SP, Brasil / Biology and ecology of Eustala taquara (Keyserling, 1892), (Araneae, Araneidae) in Serra do Japi, Jundiaí - SP, Brazil

Souza, Hebert da Silva, 1987- 24 August 2018 (has links)
Orientadores: João Vasconcellos Neto, Marcelo de Oliveira Gonzaga / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-24T05:04:24Z (GMT). No. of bitstreams: 1 Souza_HebertdaSilva_M.pdf: 4147716 bytes, checksum: 886fc92941a725beb4f3c73d25b6a031 (MD5) Previous issue date: 2013 / Resumo: O grupo das aranhas é extremamente diverso e está distribuído em praticamente todos os habitats terrestres. No entanto, a ocorrência de grande parte das espécies é condicionada por fatores abióticos e bióticos bem definidos. Dessa forma, elementos como altitude, intensidade luminosa, temperatura, umidade, bem como as interações existentes com outros organismos, como a relação entre presas e predadores, podem influenciar o padrão de distribuição e os ajustes populacionais de aranhas ao longo do tempo. A vegetação é um fator determinante para a biologia de aranhas orbitelas, pois além de providenciar condições microclimáticas adequadas, fornece abrigo e pontos de apoio para a construção de teia... Observação: O resumo, na íntegra, poderá ser visualizado no texto completo da tese digital / Abstract: The Group of spiders is extremely diverse and is distributed in practically all terrestrial habitats. However, the occurrence of most species is conditioned by abiotic and biotic factors. Thus, elements such as altitude, light intensity, temperature, humidity, as well as existing interactions with other organisms, such as the relationship between prey and predators, may influence the distribution pattern and population adjustments of spiders over time. The vegetation is a determining factor for the biology of Orb-Weavers spiders, because, in addition to providing adequate microclimatic conditions, it provides shelter and support spots for construction of webs. Eustala taquara (Araneidae) inhabits herbaceous plants and shrubs, and are difficult to be seen by blending with the dry vegetation where they lie... Note: The complete abstract is avaiable with the full electronic document / Mestrado / Biodiversidade Animal / Mestre em Biologia Animal
275

Effects of Habitat Characteristics on Amphibian Use of Aquatic and Terrestrial Environments

Dimitrie, David Anthony 01 September 2021 (has links)
No description available.
276

Ecology and diet of the caracal (Caracal caracal) on lethal and non-lethal control farms in the Karoo

Jooste, Erin Cecilia January 2020 (has links)
>Magister Scientiae - MSc / Human-wildlife conflict is an ongoing issue worldwide. Within South Africa, human-carnivore conflict (HCC) as a result of carnivore depredation on small-livestock causes large-scale losses, and promotes the use of predator management tools by farmers. Despite being one of the major offenders involved in HCC, caracals, and their ecology in particular, are understudied. This is mainly due to high levels of persecution, coupled with their elusive nature. Within the Karoo region of South Africa, pastoralists make use of large-scale lethal predator controls in an attempt to remove the offenders, or non-lethal predator controls to protect livestock and deter predators. However, the effects of these various predator control techniques on caracal ecology have not been widely tested. Therefore, the aims of this thesis were, firstly, to assess caracal diet on lethal and non-lethal treatment farms in the Karoo; secondly, to investigate the drivers of caracal habitat selection on a non-lethal farm in the Karoo; and finally, to evaluate caracal activity patterns on the non-lethal farm. To do this, I made use of two non-invasive techniques (i.e. scat analysis and camera trapping). Caracals appeared to favour natural prey across all sites, with livestock remains only found in scats collected at the lethal treatment farm. Caracals had the broadest dietary breadth on the non-lethal treatment site, and the narrowest on the lethal treatment site. The main components of caracal diet included small mammals, lagomorphs, rock hyraxes (Procavia capensis), wild ungulates and arthropods. Caracal habitat selection was explained by resource dispersion and environmental features Interestingly, the presence of livestock was not a major consideration in caracal habitat selection. Caracals were mainly nocturnal but became increasingly crepuscular during winter. In addition, caracal activity overlapped significantly with black-backed jackals (Canis mesomelas), lagomorphs and common duikers (Sylvicapra grimmia). Caracals showed plasticity in their activity patterns based on seasonal temperature fluctuations, and partially human avoidance. This study contributes to understanding how caracal ecology differs on differently managed livestock farms. Throughout this study, the importance of both a natural prey base, as well as natural lands to caracal survival have been revealed. These findings can contribute to caracal conservation in HCC areas.
277

A Multi-Scale Analysis of Jaguar (Panthera onca) and Puma (Puma concolor) Habitat Selection and Conservation in the Narrowest Section of Panama.

Craighead, Kimberly A. 02 May 2019 (has links)
No description available.
278

Die reichstrukturierte Agrarlandschaft - ein unbeachteter Lebensraum für die gefährdete Europäische Wildkatze (Felis silvestris)

Jerosch, Saskia 20 July 2021 (has links)
Seit Ende des 20. Jahrhunderts wird eine Ausbreitung der solitär lebenden und streng geschützten Europäischen Wildkatze (Felis silvestris) registriert, die sich auch aus den bewaldeten Lebensräumen in die weitgehend offene Agrarlandschaft erstreckt. Kenntnisse über Lebensraumansprüche in diesen Landschaftsausschnitten liegen bisher für die Art nicht vor. Ziel der Studie ist es, erstmalig Daten zur Raumnutzung aus einem bisher kaum bekannten Lebensraum zu erfassen. Der ökologische Erkenntnisgewinn soll Empfehlungen für lebensraumverbessernde Maßnahmen in landwirtschaftlich geprägten Kulturlandschaften erbringen, die auch den Individuenaustausch zwischen Populationen der Art fördern. Die Ergebnisse der Telemetriestudie in der Goldenen Aue belegen eine regelmäßige Nutzung der reichstrukturierten Agrarlandschaft durch etablierte Individuen. Darüber hinaus wurde ein erfolgreiches Reproduktionsereignis dokumentiert. Das Geschlechterverhältnis und die Altersstruktur der erfassten Tiere (n = 11) waren ausgeglichen. Die Aktionsraumgrößen der Kater stimmten weitgehend mit dem in bewaldeten Lebensräumen ermittelten Raumanspruch männlicher Wildkatzen überein. Weibliche Wildkatzen nutzten in der reichstrukturierten Agrarlandschaft deutlich (um ca. 60 %) kleinere Streifgebiete als ihre Artgenossinnen in den bewaldeten Lebensräumen. Die Studie bestätigt die strenge Bindung der Wildkatze an deckungsbietende Strukturen. Die Analyse zur Habitatnutzung ergaben geschlechterspezifische Unterschiede: Während weibliche Wildkatzen in dem agrarisch dominierten Landschaftsausschnitt eher eine Bindung an flächige Strukturelemente, wie Feldgehölze- und kleine Waldinseln sowie aus der Nutzung genommene Streuobstwiesen zeigten, nutzten Kater hier lineare Elemente, wie strukturreiche Uferstreifen von Still-, und Fließgewässern sowie Weg- und Ackersäume intensiver. Die Daten belegen, dass der bisher unbeachtete Lebensraum – die reichstrukturierte Agrarlandschaft - durchaus alle wichtigen Lebensraumfunktionen für die Europäische Wildkatze erfüllen kann. Ein Grund für die geringe Größe der weiblichen Streifgebiete ist eine streng auf qualitativ hochwertige Habitatstrukturen begrenzte Lebensraumnutzung. Dabei scheint neben der Nahrungsverfügbarkeit ein ausreichend hohes Angebot deckungsbietender Strukturen in der Strauch- bis Baumklasse ausschlaggebend für eine Etablierung von Weibchen zu sein. In landwirtschaftlich geprägten Kulturlandschaften ist bei einer Mindestausstattung an deckungsbietenden Habitaten mit dem Vorkommen etablierter und reproduzierender Wildkatzen zu rechnen, insbesondere in der Peripherie besiedelter Waldlebensräume. Eine Prüfung der artenschutzrechtlichen Verträglichkeit im Rahmen der planungsrechtlichen Eingriffsregelung sollte zukünftig auch auf die angrenzenden Offenlandschaften (bis zu 4km) von bewaldeten Lebensräumen ausgeweitet werden. Als lebensraumverbessernde Maßnahme wird grundsätzlich eine Erhöhung der Strukturvielfalt in der Agrarlandschaft durch Schaffung oder/und Erhaltung von kleinräumigen Strukturen wie Feldgehölzen, Hecken und breiten Feld-Gewässerrainen mit aufkommender Sukzession empfohlen. Darüber hinaus gewährt dies einen Individuenaustausch zwischen räumlich getrennt voneinander liegenden (Teil)Populationen. / Since the end of the twentieth century, the solitary and strictly protected European wildcat (Felis silvestris) has spread from wooded habitats across the largely open agricultural landscape. Knowledge about habitat requirements in these landscape sections is not yet available for the species. The aim of the study is, for the first time, to generate space use data from so far less known habitat. The ecological gain of knowledge should provide recommendations for habitat-improving measures in agriculturally influenced cultural landscapes, which also promote the exchange of individuals between populations of the species. The results from the Golden Aue prove a regular use of a richly structured agricultural landscape by established individuals. In addition, a successful reproduction event was documented. The sex ratio and the age structure of the recorded animals (n = 11) were balanced. The home range sizes of males were largely consistent with the space requirement determined in wooded habitats. In a richly structured agricultural landscape, female animals clearly used (about 60 %) smaller home ranges than their conspecifics in the wooded habitats. The study confirms the strict binding of the wildcat to cover-providing structures. Gender differences were found: While females were more likely to be bound to areal structural elements such as copses, orchards and small forest islands, males used linear elements more extensively than females, such as structurally rich riparian strips of waterbodies and field margins in the agricultural landscape. The data show that the so far neglected habitat - the richly-structured agricultural landscape - can fulfill all important habitat functions for the European wildcat. One reason for the small female home ranges is probably an exclusive use of high-quality habitats, which in addition to the food availability also provide sufficient hiding places. In agricultural landscapes, assuming at least a minimum of cover habitats, the presence of established and reproducing wildcats can be expected, at least in the periphery of forest habitats. Increasing structural diversity in the agricultural landscape through the creation or / and preservation of small-scale structures such as copses, hedgerows and broad field-watercourses with emerging succession is recommended as habitat-improving measures. In addition, it provides for an exchange of individuals between spatially separated (sub) populations. In the future, an examination of the species protection compatibility in the context of the planning intervention regulations should also be extended to the adjacent open landscapes (up to 4 km) of forested habitats.
279

Habitat Selection of Greater Sage-Grouse Centrocercus urophasianus and Northern River Otters Lontra canadensis in Utah

Westover, Matthew D. 06 December 2012 (has links) (PDF)
Greater sage-grouse populations have decreased steadily since European settlement in western North America. Reduced availability of brood-rearing habitat has been identified as a limiting factor for many populations. We used radio-telemetry to acquire locations of sage-grouse broods from 1998 to 2012 in Strawberry Valley, Utah. Using these locations and remotely-sensed imagery, we proceeded to 1) determine which features of brood-rearing habitat could be identified using widely available, fine-scale imagery 2) assess the scale at which sage-grouse selected brood-rearing habitat in our study area, and 3) create a predictive habitat model that could be applied across our large study area to identify areas of preferred brood-rearing habitat. We used AIC model selection to evaluate support for a list of variables derived from remotely-sensed imagery. We examined the relationship of explanatory variables at three scales (45, 200, and 795 meter radii). Our top model included 10 variables (percent shrub, percent grass, percent tree, percent paved road, percent riparian, meters of sage/tree edge, meters of riparian/tree edge, distance to tree, distance to transmission lines, and distance to permanent structures). Variables from each scale were represented in our top model with the majority of scale-sensitive variables suggesting selection at the larger (795 meter) scale. When applied to our study area our top model predicted 75% of naive brood locations suggesting reasonable success using this method and widely available NAIP (National Agricultural Imagery Program) imagery. We encourage application of this method to other sage-grouse populations and species of conservation concern. The northern river otter is a cryptic semi-aquatic predator that establishes and uses latrines. Highly used river otter latrines indicate otter "activity centers" since frequency of scat deposition is thought to be correlated to frequency of habitat use. We compared an indirect method (scat counts) and a direct method (remote cameras) of determining latrine utilization in order to assess the accuracy of the commonly used indirect method. To further compare these methods we used them to examine effects of anthropogenic disturbance on otters of the Provo River in Utah. We found that overall the direct and indirect methods were highly correlated. There was significant seasonal variation in the degree of correlation between the indirect and direct methods with correlation being significantly higher in the summer. We found similar results when using these methods to examine effects of anthropogenic disturbance. For each method the distance of the latrine to trails was significant in one of the top competing models. We suggest that space use of otters in our study area is being affected by anthropogenic disturbance as measured by distance to trails. We also suggest that scat counts should only be conducted during the summer when they correlate best with actual levels of otter activity.
280

Seasonal And Diel Patterns Of Manatee Habitat Use

Ross, Monica Ann 01 January 2007 (has links)
State and Federal agencies have created sanctuaries and speed zones to help reduce manatee mortality while incorporating the recreational and commercial resource needs of these same habitats for humans. Specific habitat resources are considered necessary to increase manatee survivorship. We have only recently begun to address how manatees use some of these resources based on physiological or reproductive strategies. In this study, I quantified patterns of habitat use during seasonal and diel periods for different sex and reproductive manatee classes using data from a radio-telemetry study conducted by the Florida Fish and Wildlife Conservation Commission during 1991-1996. I used five environmental geographic data layers: bathymetry, distance to seagrass, distance to shoreline, distance to warm water refuge sites, and distance to fresh water sources, to discriminate seasonal and diel habitat use patterns for different manatee classes: males (M), females with calves (FWC), and females without calves (FNC). Mean occupancy values were calculated for environmental variable locations and seasonal, diel, and manatee class differences were tested using a Multi-Response Permutation Procedure (MRPP). Nonmetric Multidimensional Scaling (NMS) was used to visualize the ordination patterns of the manatee classes and to assess importance of correlated environmental variables. Significant differences in habitat use were noted between summer and winter based on distances to warm water, seagrass, and fresh water sources but similar habitat use patterns were exhibited within summer diel periods among manatee classes. All manatee classes appeared to have used a higher proportion of locations closer in proximity to seagrass at night than day in winter indicating a disproportionate difference in feeding bouts between diel periods. These differences may be attributed to adjusting feeding strategies to reduce thermoregulatory costs or to decrease human interactions. Differences in patterns were exhibited for the winter diel periods specifically for the FWC manatee classes during winter days. FWC had a higher proportion of locations within the warm water refuges during the day indicating a possible trade off situation between food consumption and thermal exposure. This study demonstrates coarse and fine scale patterns of variation in habitat use for manatees both seasonally and daily within winter. It also suggests that during winter months, manatees were not just utilizing their habitat but they appeared to have preferences and selection for certain habitat types. Recovery of a species is greatly enhanced when patterns of habitat use within the species' environment has been clearly defined. Understanding more specifically what types of habitats manatees choose might allow management to adjust strategies for protection of key habitats while encouraging further recovery of this species.

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