North American River Otter (Lontra Canadensis) Presence and Habitat Analysis in Florida as Compared to Historical Data PDF Download
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Author: Samantha Wilber
Publisher:
ISBN:
Category : Ecology
Languages : en
Pages :
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North American river otters are considered common in the state of Florida, but their populations have not been studied since the 1980's. Since that time, Florida's human population has more than doubled, and many natural areas of Florida have been developed. The aim of this study was to determine the presence or absence of river otters at locations in Florida which they historically inhabited. Forty-six sample sites where otters were historically found were obtained from the Florida Museum of Natural History Mammals Master Database (FMNH MMD). These sites were condensed to two focus areas, in and around Alachua and Collier Counties, where the sites were most highly clustered. Each site was surveyed to determine the presence or absence of river otters and to determine the suitability of the site's environment for otter habitation. Sites with favorable habitat features for otters were surveyed a second time. River otters were not found at any site. Only 9 of the 46 sites had permanent water and only 8 of those had other habitat features preferred by otters. Therefore, only 17.39% of sites that historically supported otters likely still have the ability to do so. Loss of water over time is most likely the result of human disturbances such as the draining, damming, and canalizing of wetlands. As a result of this loss of natural habitat, river otters have become increasingly common in urban areas wither preferred habitat features, even if they are man-made. The increased presence near humans may have led to the apparently inaccurate assumption that otters are common, and, therefore, do not need protection.
Author: Samantha Wilber
Publisher:
ISBN:
Category : Ecology
Languages : en
Pages :
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Book Description
North American river otters are considered common in the state of Florida, but their populations have not been studied since the 1980's. Since that time, Florida's human population has more than doubled, and many natural areas of Florida have been developed. The aim of this study was to determine the presence or absence of river otters at locations in Florida which they historically inhabited. Forty-six sample sites where otters were historically found were obtained from the Florida Museum of Natural History Mammals Master Database (FMNH MMD). These sites were condensed to two focus areas, in and around Alachua and Collier Counties, where the sites were most highly clustered. Each site was surveyed to determine the presence or absence of river otters and to determine the suitability of the site's environment for otter habitation. Sites with favorable habitat features for otters were surveyed a second time. River otters were not found at any site. Only 9 of the 46 sites had permanent water and only 8 of those had other habitat features preferred by otters. Therefore, only 17.39% of sites that historically supported otters likely still have the ability to do so. Loss of water over time is most likely the result of human disturbances such as the draining, damming, and canalizing of wetlands. As a result of this loss of natural habitat, river otters have become increasingly common in urban areas wither preferred habitat features, even if they are man-made. The increased presence near humans may have led to the apparently inaccurate assumption that otters are common, and, therefore, do not need protection.
Author: Danaan DeNeve Weeks
Publisher:
ISBN:
Category :
Languages : en
Pages : 226
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The North American river otter is a semiaquatic carnivore that occupies freshwater habitats across most of North America, and is a conservation symbol across most of its range. It is used as an indicator species, a keystone species, an umbrella species, and an example of conservation success. The broad distribution of river otters suggests a broad range of habitat tolerances, but they appear to be highly sensitive to anthropogenic habitat alterations. This apparently conflicting robustness across habitat types and sensitivity to habitat change has baffled researchers for decades. Using morphometric, modeling, and synthetic approaches I explored how otters relate to their environment on a broad scale to gain a better understanding of the conditions to which they are robust, the conditions to which they are sensitive, and the mechanisms by which they adapt to varying environments. Using Maximum Entropy species distribution models I determined that river otter distributions are not strongly affected by climate or macro-environmental variables. Using geometric morphometric methods to examine how cranial shape varies across geographic and ecological space, I determined that morphological variation which may affect feeding and locomotion occurs more intensely at local than broad scales, indicating local morphological adaptation is not strong in this species. Finally, a review of the phylogeography and ecology of river otters and related species indicated that this species evolved from a low-speciation lineage that tends to produce species that can occupy a wide variety of environments without undergoing evolutionary change. Overall I determined that river otters do indeed have a broad ecological niche, and do not respond strongly to climatic or environmental differences or changes across their habitats through altering their distributions or locally adapting. Evidence suggests that river otters may respond strongly to anthropogenic alterations of their habitats because anthropogenically-induced habitat alterations tend to have strong consequences for aquatic food chains, and otters may be more reliant on robust food webs than they are on other aspects of their habitats. These findings have implications for how we think of otter conservation and the conservation of species and ecosystems that are strongly affected by otter presence, as well as what otters indicate about their habitat quality. Additionally, these results may shed light on the ecologies of other mustelid carnivores. In the first chapter of my dissertation I conducted a review of the phylogenetics and biogeography of North and South American river otters to investigate how geography and environmental change have driven river otter evolution in the Americas, and how this informs the ecology of the modern species. I focused first on reviewing the biogeography and evolutionary history of Lontra and Pteronura, and then on the modern ecology, threats, and conservations status of each of the four modern species of Lontra and the single extant species of Pteronura. I chose to review these species because they overlap in geographic and environmental space, and because their shared history provides means for an evolutionarily-grounded examination of relative rarity, specialization, and level of conservation concern. I found that speciation between American otters primarily occurs allopatrically, and there is little functional differentiation in response to allopatric speciation, though they do appear to have the ability to adapt in response to extreme conditions when necessary. Additionally, allopatric speciation primarily occurs in response to changes in waterway connectivity, which is also responsible for changes in population connectivity within the modern species. Most otters have less specific habitat requirements than previously thought, as all species of Lontra persist across a wide variety of climates and semi-aquatic environments, and most of them do so without exhibiting a strong evolutionary response. All American river otters exhibit a strong sensitivity to anthropogenic habitat destruction, though several of them have also shown some ability to coexist with humans. Evidence from this study provides strong indication that this has to do with how human activities near waterways affect food webs, and more generally that on closer examination many habitat components previously thought to be requirements for otters may be better interpreted as indicators of food availability. In the second chapter of my dissertation I use species distribution modeling to examine river otter associations with climate and environment across their range to explore their apparently conflicting robustness to habitat change and sensitivity to human presence. Specifically, I examined the climate and landcover variables that constrain the geographic distribution of otters. I obtained otter occurrences from GBIF and BISON biodiversity databases, climate variables from BIOCLIM, and environmental layers from NASA's SEDAC program. I built Maximum Entropy species distribution models at 80 and 150 km spatial thinning and varying numbers of background points. The combined model at 80 km spatial thinning and default number of background points produced the highest quality models. Six climatic and landcover variables explained over 10% of otter distributions each: open shrubland, net primary productivity, urban/built, water, annual mean temperature, and precipitation of coldest quarter. Of these variables I determined that water, annual mean temperature, and precipitation of coldest quarter likely have biological significance. However, the predicted range map generated by these models do not match river otter distributions generated by the IUCN and NatureServe. This is likely due to incomplete occurrence data because of low reporting in parts of the species range. I conclude based on these data that river otters have broad climatic and habitat tolerances (as there are six weakly predictive variables as opposed to 1-2 strongly controlling variables) and that local habitat factors, such as intact-ness of riverine food webs, may have greater impact on otter distributions than broad regional variables. Additionally, I call for improved monitoring and reporting of this and other broadly-distributed species to ensure we can adequately track their habitat requirements and conservation status. In the third chapter of my dissertation I use geometric morphometrics to explore the role of cranial morphological variation in otter persistence across the array of otter habitats. I address two research questions: 1. Is there morphological variation and structure in river otters across subspecies? 2. Is morphological variation in river otters best explained by a pattern of isolation by distance or isolation by ecology? I obtained 100 river otter crania from across the species range from museums. I 3-D scanned them using a Geomagic 3-D scanner and landmarked them using the IDAV Landmark program. To answer Q1 I conducted discriminant function analyses Procrustes ANOVAs and a Principal Components Analysis. None of these tests revealed strong morphological patterning, indicating there is not morphological differentiation across subspecies in cranial shape. T address Q2 I conducted Mantel tests and a Multiple Matrix Regression with Randomization (MMRR) on the relationship between morphological distance and geographic, climatic, and environmental distance. Both the Mantel test and the MMRR results indicated no significant relationship between morphological distance and climatic or environmental distance in otter crania. Both indicated a weak but negative relationship between morphological distance and geographic distance, indicating morphological variation is greater at short geographic distances and lower at broad geographic distances. I conclude that there is significant cranial variation between individuals, but little definable structure in this variation. The weak but significant (and potentially complex) relationship between geographic and morphological distance indicates the possibility that diversifying selection across smaller spatial scales may be more important than differentiation across broader populations, possibly indicating individual specialization within a generalist population.
Author: Kevin Ross Kimber
Publisher:
ISBN:
Category :
Languages : en
Pages : 554
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Author: Dr. Richard A. NeSmith
Publisher: Applied Principles of Education & Learning
ISBN:
Category : Juvenile Nonfiction
Languages : en
Pages : 34
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Book Description
Do you ever wonder about the life of otters? Do you know where they sleep? Do you want to learn about their social behaviors, diet, or how they swim through the water so gracefully? Anything and everything you ever wondered about these curious creatures can be found in this easy to read, informative book. The wonderful pictures included in this book have captured some of the many reasons people are drawn to these adorable animals over the years. I have personally worked with many different animals, and I can honestly say that otters are genuinely one of the most interesting of the animal kingdom. Once you read this book, you will understand why I, as well as many others, have a fascination with otters. Laurie Aleixo, DVM, Fort Pierce, Florida
Author:
Publisher:
ISBN:
Category : Lutra canadensis
Languages : en
Pages : 142
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Author: Shannon Michael Crowley
Publisher:
ISBN:
Category : Otters
Languages : en
Pages : 0
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I investigated patterns in river otter (Lontra canadensis) diet, habitat selection, and behavior at latrine sites in central British Columbia during the ice-free season in 2007 and 2008. I used an Information Theoretic Model Comparison approach to investigate the relationships among otter diet and temporal/spatial parameters and habitat characteristics and the presence, consistency, and intensity of otter activity. Data were collected every two weeks at latrine sites visited by otters. I used a combination of scat content and stable-isotope analysis to investigate the contributions of different prey items to otter diet. Binary and count models were used to predict the presence of individual prey items and number of scats, respectively. A combination of fish spawning period, water body type, and individual lake best described the presence of salmonids, minnows, and insects in otter scat. The relative effects of season and water body varied considerably among the three prey groups found in scats. Scat deposition was positively influenced by a time period when no fish were spawning (early July) and to the kokanee (Oncorhynchus nerka) spawning period (early September). In general, the stable-isotope analysis agreed with the results of the scat content analysis showing a dominance of fish in the diet of otter and a small contribution from other prey sources. The stable-isotope analysis, however, suggested a larger contribution from sockeye salmon and birds relative to data from the scat content analysis. I followed the diet analyses with an investigation of factors that influenced the selection of latrine sites and activity of otter at multiple spatial and behavioural scales. For fine-scale analyses, I performed field measurements at latrine sites and spatially adjacent random sites. At the course landscape scale, I used Geographic Information Systems (GIS) to examine environmental variables that described the broader Tezzeron and Pinchi lake study area. Working at these two spatial scales, I used binary models to predict the presence and consistency (high vs. low use) of latrine sites, and count models to predict the intensity (e.g., number of scat) of latrine site use. Relative to the coarse-scale analysis, I found that habitat characteristics at the fine scale were better at predicting latrine sites. In general, fine-scale selection was influenced by parameters that described visual obscurity, larger trees, and characteristics of conifer trees. The presence of latrine sites at the coarse scale was not accurately described by any of the variables I tested. The consistency and intensity of activity at latrine sites at the coarse scale, however, was best predicted by characteristics of aquatic habitat beneficial to fish. The findings of this study provide the baseline information necessary for developing techniques for monitoring otter populations and assessing otter habitat that can be incorporated into management, monitoring, and conservation strategies.
Author: Jordan I. Bailey
Publisher:
ISBN:
Category : Latitude
Languages : en
Pages : 110
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"Historically, North American river otters (Lontra canadensis) were widely dispersed throughout the North American continent. Trapping pressures and urbanization have led to regional exclusion of North American river otter populations from historic habitats, leading the Association of Zoos and Aquariums to spearhead conservation and captive breeding efforts to maintain genetic diversity of the aquatic mustelid. Difficulties in consistently breeding captive North American river otters have spotlighted a need to understand how geography and life history of adult individuals influence reproductive events. This study analyzed the AZA studbook records for all litters born in captivity from 2008 to 2014 (N = 47) to assess whether any correlations existed between historical data and timing of parturition events. ANOVA tests found significant differences in mean parturition date between litters by dam origin region (F = 6.09, p-value = 0.018) and by parturition location (F = 12.73, p-value = 0.001). A Mann-Whitney u test found a difference (p-value = 0.0365) between median parturition dates of litters born in the north and those born in the south regions. PCA testing showed that the data form independent groups by both dam and sire origin latitudes, confirming the existence of a significant relationship between latitude and the timing of reproductive events. However, this study did not conclusively determine which latitude (the origin of the dam, origin of the sire, or latitude at the time of breeding) has the most influence on reproductive events among the captive North American river otter population. Future work should strive to identify other variables related to physiological condition and/or genetic variation between North American river otter subspecies. These factors may lead to more discreet groups and will likely aid in the development of a predictive model of parturition timing among the captive population using known life history data."--Abstract.
Author:
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Category :
Languages : en
Pages :
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The North American river otter (Lontra canadensis) was extirpated throughout much of its range but is now recovering in many areas. Consequently, there is a need to determine river otter occupancy and habitat associations. We conducted sign surveys from January to April 2008 and 2009 in eastern Kansas to assess how local- and landscape-scale habitat affects river otter occupancy and how survey methods and habitat affect the detectability of river otter sign. Multiple observers surveyed 3-9 400-m stretches of stream and reservoir shorelines for 110 randomly-selected sites and measured local-scale (within a 100 m buffer of site) habitat variables (e.g., stream order, sinuosity, proportion of land cover types) and landscape-scale (Hydrological Unit Code 14 watershed) habitat variables (e.g., road density, shoreline diversity, proportion of land cover types). We then modeled occupancy and detection probability as a function of these covariates using Program PRESENCE. The overall probability of occupancy accounting for detection probability was 0.329. The best-fitting model indicated river otter occupancy increased with the proportion of woodland cover and decreased with the proportion of cropland and grassland cover at the local scale. The best-fitting model also indicated occupancy increased with decreased shoreline diversity, waterbody density, and stream density at the landscape scale, possibly because of the influence of large reservoirs in the watershed. Occupancy was not affected by land cover or human disturbance at the landscape scale, perhaps due to our relatively homogeneous study area or because river otters are habitat generalists. Detection probability for 400-m surveys was highest in mud substrates (p = 0.600) and lowest in snow (p = 0.180) and litter substrates (p = 0.267). Detection probability for scat was more than double that for tracks, and detection probabilities were 17-64% lower for novice observers than experienced observers. Detection probability also increased with survey length. Sign surveys are a useful technique for monitoring many species, including river otters, and accounting for detection probability will improve estimation of occupancy. Furthermore, understanding the ecological factors and the scale important to river otter occurrence will be useful in identifying areas for restoration and management efforts.
Author:
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Category :
Languages : en
Pages :
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Abstract : As loss of habitat, fragmentation, and climate change continue to alter natural habitats, connectivity of the landscape becomes necessary for species conservation. My dissertation covers several of the factors that affect connectivity for North American river otter (Lontra canadensis) populations in the Upper Peninsula of Michigan. First, we developed a new non-invasive method that captures DNA from snow tracks to identify individual otters. We were successful in identifying 66 individual otters from 87 putative otter samples. This allowed for estimation of population density and genetic diversity for connectivity analyses. Next we conducted a systematic review of the literature and meta-analyses to determine habitat variables that otters select. At the latrine scale, otters were positively associated with forested areas, a high percentage of overhead cover, and complex shorelines. Otters avoided areas with high percentage of herbaceous and shrub cover. At the river segment scale, otters avoided human disturbance and were found in areas with a high percentage of forest, higher number of ponds, closer to lakes, and deeper water than random segments. The significant variables from the meta-analyses were applied to resource selection functions (RSF). The Meta-analysis RSF model was compared with a use/random RSF model, use/road-stream crossing RSF model, and a null model. The Meta-Analysis RSF model did not predict use as well as the use/road-stream crossing RSF model, indicating that meta-analyses may be helpful in determining important habitat variables, however, the coefficients may not be transferrable across the otter's range. Toxoplasma gondii is a parasite that may be affecting the connectivity of otter populations. We found that prevalence was 28% in sampled otters and 69% percent of T. gondii positives were Type #4 clones. When prevalence was modeled with other factors, the presence of Sarcocystis, the percent area of exotic vegetation, the percent area of agriculture, and sex explained 78% of the variation. Understanding the connectivity of the landscape is dependent on multiple variables that interact on different spatial and temporal scales. However, maintaining connectivity for wildlife populations is necessary for protecting biodiversity in a changing world.
Author: Sara A. Adamczak
Publisher:
ISBN:
Category : North American river otter
Languages : en
Pages : 76
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The North American river otter (Lontra canadensis) is a semi-aquatic, apex predator that has undergone vast changes in its distribution in the past few decades. In the Midwest, river otters were extirpated and later reintroduced with little follow up on their population status. It is important to assess the current population in order to make the proper management decisions statewide. In addition to the lack of demographic knowledge, spatio-temporal variation in the North American river otter (Lontra canadensis) diet is not well understood. As resource availability and usage can influence population demographics, it is important to assess river otter diet to properly understand river otter ecology. In order to assess the river otter population in Ohio, the Ohio Department of Natural Resources (ODNR) requested carcass submission by licensed trappers. Throughout the 2016-2017 and 2017-2018 trapping seasons, 107 river otter carcasses were collected. Necropsies were performed to assess age and sex, reproductive status, and stable-isotope informed diet composition. Reproductive rates were determined from counting corpora lutea in female river otters. Demographic data were compared to the 2005-2008 harvests seasons, when river otter trapping was first reinstated. Samples of river otter muscle were collected, prepared and assessed for stable isotopes of 13C and 15N to estimate the variability in the dietary contribution of multiple prey sources by age, sex, and location.
