Altitudinal gradient of Eurasian otter (Lutra lutra) food niche in Mediterranean habitats

2009 ◽  
Vol 87 (4) ◽  
pp. 285-291 ◽  
Author(s):  
Luigi Remonti ◽  
Alessandro Balestrieri ◽  
Claudio Prigioni
Keyword(s):  
Altitudinal Gradient ◽  
Fish Assemblages ◽  
Prey Availability ◽  
Small Rivers ◽  
Lutra Lutra ◽  
Sampling Station ◽  
Alternative Prey ◽  
Predator Species ◽  
Trophic Diversity ◽  
Eurasian Otter

The effects of geographical factors, such as latitude and altitude, on climate are known to influence the food habits of predator species distributed over a broad distribution range. A sharp latitudinal gradient in the diet of the Eurasian otter ( Lutra lutra (L., 1758)), that is an increase of trophic diversity from temperate to Mediterranean Europe, has been described recently. Altitude, affecting the diversity of fish assemblages and hence prey availability for otters, could also be a key factor influencing otter diet. With the aim of testing for the presence of an altitudinal gradient in otter diet in the Mediterranean area, we assessed the composition of diet at 24 sampling reaches spread in three main river catchments of southern Italy. The analysis of 1885 spraints revealed that fish were the main prey of otters, followed by amphibians, while other food items were of lesser significance, although crustaceans could be locally important. The altitude of the sampling station was negatively correlated with fish consumption and positively correlated with otter trophic diversity; at higher altitudes, alternative prey (particularly amphibians) were included in otter diet. The reduction of fish availability with elevation plays a major role in shaping this dietary pattern. The ability of otters to exploit alternative prey, such as amphibians, could allow the colonization of small rivers sustaining a low fish biomass.

scholarly journals Hydrological stability and otter trophic diversity: a scale-insensitive pattern?

2008 ◽  
Vol 86 (10) ◽  
pp. 1152-1158 ◽  
Author(s):  
M. Clavero ◽  
J. Prenda ◽  
F. Blanco-Garrido ◽  
M. Delibes
Keyword(s):  
Iberian Peninsula ◽  
Fish Consumption ◽  
Aquatic Ecosystems ◽  
Fish Populations ◽  
Lutra Lutra ◽  
Mediterranean Streams ◽  
Diet Diversity ◽  
Trophic Diversity ◽  
Eurasian Otter ◽  
The Stability

Two recent works related Eurasian otter ( Lutra lutra (L., 1758)) trophic patterns over large areas with the stability of aquatic ecosystems. Higher levels of instability lead to reduced availability and (or) predictability of fish, and consequently, to a decrease in fish consumption by otters. The aim of the present study is to test these macrogeographical patterns in otter diet at regional and local scales. We analysed otter diet in Mediterranean streams in southwestern Iberian Peninsula where clear hydrological stability gradients (related to drainage area or distance to the sea) could be defined. Hydrological stability was directly related to fish consumption and inversely to otter diet diversity in terms of occurrence and biomass, both at regional and local scales. The level of stability of aquatic ecosystems appears to be a critical indirect factor that modulates otter diet through its effects on fish populations. The resulting trophic patterns are maintained from local to macrogeographical scales.

Prey availability and diet of the Eurasian otter (Lutra lutra) on a large reservoir and associated tributaries

2007 ◽  
Vol 85 (11) ◽  
pp. 1125-1135 ◽  
Author(s):  
T. Sales-Luís ◽  
N.M. Pedroso ◽  
M. Santos-Reis
Keyword(s):  
Prey Species ◽  
Prey Availability ◽  
Lepomis Gibbosus ◽  
Lutra Lutra ◽  
Large Reservoir ◽  
Main Prey ◽  
Eurasian Otter ◽  
Hydroelectric Dam ◽  
Central Portugal ◽  
Refuge Areas

Eurasian otter, Lutra lutra (L., 1758), spraints collected at the Aguieira hydroelectric dam (central Portugal, n = 916) and tributaries (n = 412) were analysed to assess diet compared with prey availability. Fish and crayfish abundances in the reservoir were assessed with fyke and trammel nets. Prey availability in the tributaries was estimated by electrofishing. In both the reservoir and its tributaries, fish were the main prey and consisted predominantly of Lepomis gibbosus (L., 1758) (60%–65% of occurrences), which is an introduced species of Centrachidae that is abundant in the reservoir but is almost absent in the tributaries. These data suggest that otters using the tributaries feed predominantly in the reservoir. Seasonal dietary variations corresponded to increased availability of nonfish prey categories. Capture vs. consumption analyses demonstrated that otters did not consume L. gibbosus according to its availability. In fact, L. gibbosus was consumed less frequently when other prey species were more available (e.g., amphibians, eels, barbells). The tributaries offer important otter refuge areas that are scarce at the edge of the reservoir, and so, in large reservoirs care should be taken to minimize disturbance in the surrounding catchments. Results indicate that otter populations make use of these conjoint systems to ensure their survival.

Structure and Seasonal Fluctuations of Rocky Littoral Fish Assemblages in South-Western Portugal: Implications for Otter Prey Availability

1995 ◽  
Vol 75 (4) ◽  
pp. 833-847 ◽  
Author(s):  
Pedro Rui Beja
Keyword(s):  
Seasonal Variation ◽  
Fish Assemblages ◽  
Prey Availability ◽  
Early Spring ◽  
The Other ◽  
Rocky Intertidal ◽  
Lutra Lutra ◽  
Seasonal Fluctuations ◽  
Littoral Fish ◽  
Conger Conger

The fish assemblages of rocky intertidal and subtidal (<3 m depth) habitats of the south-western Portuguese coast were sampled between May 1992 and November 1993, using traps, angling and hand-netting, to investigate their structure and seasonal dynamics. The main purpose of the study was to describe the patterns of prey availability for marine-feeding otters (Lutra lutra L., Mammalia) in south-western Portugal, and to compare these with other areas in Europe. A total of 475 fish of 14 species was captured over 150 d of trapping (788 trap-days), and 1575 fish of 15 species were captured over 24 d of angling (76.3h). Hand-netting was carried out occasionally, to supplement the observations from the other methods, and only 96 fish of seven species were captured. The three methods yielded different patterns of the fish assemblage: giant gobies (Gobius cobitis Pallas, 33.7%) and rock gobies (G. paganellus L., 22.9%) were the most frequently trapped fish; corkwing wrasse (Symphodus melons (L.), 81.2%) were the usual species caught by angling; shannies (Lipophrys pholis (L.), 42.7%) and Montagu's blennies (Coryphoblennius galerita (L.), 28.1%) were the most frequently netted species. Conger eels (Conger conger (L.)), giant gobies and shannies showed an uneven distribution along the coast, occurring most frequently in schist shelves, rather than in areas of large sandstone boulders. There was a large seasonal variation, with the catches of most species peaking in winter and early spring, including the majority of those most important in the diet of otters: conger eels, shore rocklings (Gaidropsarus mediterraneus L.), rock gobies and corkwing wrasse. This was also the period when the individuals of several species were heaviest.

Pulmonary hair embolism in a rescued free-ranging Eurasian otter Lutra lutra in Kinmen, Taiwan

2020 ◽  
Vol 142 ◽  
pp. 55-61
Author(s):  
WT Li ◽  
YL Chiang ◽  
TY Chen ◽  
CL Lai
Keyword(s):  
Foreign Body ◽  
Traumatic Injury ◽  
Lung Parenchyma ◽  
Giant Cells ◽  
Hair Shaft ◽  
Lutra Lutra ◽  
Lung Lobe ◽  
Eurasian Otter ◽  
Foreign Body Giant Cells ◽  
Free Ranging

Eurasian otters Lutra lutra are listed as Near Threatened on the IUCN Red List and are imperiled by habitat loss, water pollution, and poaching. Harassment and attacks by stray animals are also recognized threats to the health of wild Eurasian otters. Pulmonary hair embolism is a possible complication in animals with deep traumatic injury, but to date no cases have been reported in wildlife. A free-ranging, adult male Eurasian otter was rescued due to severe emaciation and multiple bite wounds. The otter died 3 d after rescue and was necropsied. Grossly, a 1.5 × 1.5 × 1.5 cm firm nodule was observed in the left cranial lung lobe. Histologically, a fragment of hair shaft surrounded by multinucleated foreign body giant cells was observed in a medium-sized vein, and extensive eosinophilic infiltration was noted in the adjacent vascular wall and lung parenchyma. Based on the gross and histological findings, the pulmonary lesion was consistent with eosinophilic pneumonia and vasculitis induced by hair embolism. The presence of well-formed multinucleated foreign body giant cells and eosinophils may imply a late stage of foreign body reaction, and thus the presumptive source of hair embolism is an animal bite. This is the first report of pulmonary hair embolism associated with animal bite in a rescued free-ranging Eurasian otter.

Distribution and diet of recovering Eurasian otter (Lutra lutra) along the natural-to-urban habitat gradient (river Segura, SE Spain)

2021 ◽  
Author(s):  
Ettore Emanuele Dettori ◽  
Alessandro Balestrieri ◽  
Victor Manuel Zapata-Perez ◽  
Daniel Bruno ◽  
Nuria Rubio-Saura ◽  
...  
Keyword(s):  
Urban Habitat ◽  
Lutra Lutra ◽  
Se Spain ◽  
Eurasian Otter ◽  
Habitat Gradient

scholarly journals Eurasian otter (Lutra lutra) diet as an early indicator of recovery in defaunated river communities

2020 ◽  
Vol 117 ◽  
pp. 106547
Author(s):  
Marta Narváez ◽  
Sonia Cabezas ◽  
Francisco Blanco-Garrido ◽  
Raquel Baos ◽  
Miguel Clavero ◽  
...  
Keyword(s):  
Lutra Lutra ◽  
Early Indicator ◽  
Eurasian Otter ◽  
River Communities

scholarly journals Making inference from wildlife collision data: inferring predator absence from prey strikes

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3014 ◽  
Author(s):  
Peter Caley ◽  
Geoffrey R. Hosack ◽  
Simon C. Barry
Keyword(s):  
Prey Species ◽  
Red Fox ◽  
Prey Availability ◽  
Numerical Response ◽  
Practical Application ◽  
Ecological Inference ◽  
Predator Species ◽  
New Approach ◽  
Predictive Probability ◽  
Irreducible Uncertainty

Wildlife collision data are ubiquitous, though challenging for making ecological inference due to typically irreducible uncertainty relating to the sampling process. We illustrate a new approach that is useful for generating inference from predator data arising from wildlife collisions. By simply conditioning on a second prey species sampled via the same collision process, and by using a biologically realistic numerical response functions, we can produce a coherent numerical response relationship between predator and prey. This relationship can then be used to make inference on the population size of the predator species, including the probability of extinction. The statistical conditioning enables us to account for unmeasured variation in factors influencing the runway strike incidence for individual airports and to enable valid comparisons. A practical application of the approach for testing hypotheses about the distribution and abundance of a predator species is illustrated using the hypothesized red fox incursion into Tasmania, Australia. We estimate that conditional on the numerical response between fox and lagomorph runway strikes on mainland Australia, the predictive probability of observing no runway strikes of foxes in Tasmania after observing 15 lagomorph strikes is 0.001. We conclude there is enough evidence to safely reject the null hypothesis that there is a widespread red fox population in Tasmania at a population density consistent with prey availability. The method is novel and has potential wider application.

Using an individual-based model of fish assemblages to study the response of size spectra to changes in fishing

2004 ◽  
Vol 61 (3) ◽  
pp. 414-431 ◽  
Author(s):  
Yunne-Jai Shin ◽  
Philippe Cury
Keyword(s):  
Fish Assemblages ◽  
Prey Availability ◽  
Empirical Studies ◽  
Marine Ecosystem ◽  
Predatory Fish ◽  
Size Spectrum ◽  
Individual Based Model ◽  
Size Spectra ◽  
Predation Mortality ◽  
Body Shapes

For most fish species, strong environmental constraints imposed by living in an aquatic medium have produced converging streamlined body forms without prehensile appendices. This similarity in body shapes highlights a common predation constraint: a predatory fish must have a jaw large enough to swallow its prey. Fish diets may then reflect local prey availability and predator–prey size ratios. Based on this size-based opportunistic predation process, the multispecies individual-based model OSMOSE (Object-oriented Simulator of Marine ecOSystem Exploitation) is used to investigate to what extent the size distribution of fish communities can contribute to better our understanding of the functioning of marine food webs and the ecosystem effects of fishing. Strong similarity in shape is found between simulated size spectra and those described in empirical studies. The existence of a curvature towards small size classes is discussed in the light of the size-based predation hypothesis, which implies that smaller fish may undergo higher predation mortality. Applying linear and quadratic regressions to the simulated size spectra allows the detection of variations in fishing pressure and the proposal of different ways to quantify them. In particular, it is shown that the slope of the size spectrum decreases quasilinearly with fishing mortality and that the curvature could help to detect ecosystem overexploitation.

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