Population Demographics and Diet Variation of the North American River Otter (Lontra Canadensis) in Ohio, USA PDF Download
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Author: Sara A. Adamczak
Publisher:
ISBN:
Category : North American river otter
Languages : en
Pages : 76
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Book Description
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.
Author: Sara A. Adamczak
Publisher:
ISBN:
Category : North American river otter
Languages : en
Pages : 76
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Book Description
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.
Author: Charles Thomas Parise
Publisher:
ISBN:
Category : Animal populations
Languages : en
Pages : 0
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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 11
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Abstract: Historically, river otters (Lontra canadensis) were abundant in aquatic systems throughout the country. By the 1830's, river otter numbers had been drastically reduced due to unregulated trapping and habitat destruction. By 1977, otters had been reduced to 75% of their historical range and completely eradicated from several states, including Ohio. Improved conditions in potential otter habitat, along with concern over the severe decline of this species led many states to develop plans to restore otter populations. From 1986-1993, Ohio implemented its own reintroduction plan in which 123 river otters were released at four locations in Eastern Ohio. Since 1993, the Ohio Division of Wildlife has used various methods to monitor the otter population and has documented otter presence in 67 of Ohio's 88 counties. This perceived abundance of river otters led management authorities to implement a harvest as a way of controlling population growth and mitigating conflicts. However, more information on Ohio's river otter population is needed not only to ensure the continued success of the reintroduction program, but also because river otters are listed as an Appendix II species by CITES.
Author: Kevin Ross Kimber
Publisher:
ISBN:
Category :
Languages : en
Pages : 554
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Author: Melissa Skyer
Publisher:
ISBN:
Category : North American river otter
Languages : en
Pages : 88
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"River otters were re-introduced to Western New York by the Department of Environmental Conservation between 1995 and 2000. The success of this population relies heavily on the availability of suitable prey. Diet was investigated via frequency of prey occurrence in scats from 2004-2006. Overall diet was comprised mostly of fish and crayfish. The major fish taxa were Centrarchidae (sunfish), Cyprinidae (carp), and Salmonidae (trout); less common were Esocidae (pike) and Castostomidae (sucker). All fish species combined ocurred at 100% frequency during the winter and spring months, but declined during the summer and fall. Sunfish prey were at their highest frequency in the winter and spring months (50-60%), and tapered off to 10-20% in the summer and fall. Carp in the diet showed a seasonal trend, highest in the spring at 30%, 10-20% during the summer and winter, and
Author: Danaan DeNeve Weeks
Publisher:
ISBN:
Category :
Languages : en
Pages : 226
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Book Description
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: Kristin E. Brzeski
Publisher:
ISBN:
Category : North American river otter
Languages : en
Pages : 134
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Author:
Publisher:
ISBN:
Category : Lutra canadensis
Languages : en
Pages : 142
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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: Hilary A.. Cosby
Publisher:
ISBN:
Category : Aquatic habitats
Languages : en
Pages : 130
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