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.

The influence of resource seasonality on the breeding patterns of the Eurasian otter (Lutra lutra) in Mediterranean habitats

2002 ◽  
Vol 80 (12) ◽  
pp. 2178-2189 ◽  
Author(s):  
Jordi Ruiz-Olmo ◽  
Josep Maria Olmo-Vidal ◽  
Sisco Mañas ◽  
Antoni Batet
Keyword(s):  
Prey Species ◽  
Procambarus Clarkii ◽  
Seasonal Pattern ◽  
Seasonal Fluctuation ◽  
Lutra Lutra ◽  
Mediterranean Rivers ◽  
Ebro Basin ◽  
Eurasian Otter ◽  
Mediterranean Habitats ◽  
Energy Needs

Litters of small Eurasian otter (Lutra lutra) cubs ranged from one to four, with those of one and two accounting for 95%. Significant variations were found between locations and according to the main diet (average ranging between 1.1 and 2.4 cubs/female). We found a seasonal pattern in otter breeding in some areas, being different in each. In the Prepyrenees, most births took place between March and June (85%). In Mediterranean rivers of the Ebro basin, most births occurred between December and February (57%). In both, the small cubs were found outside the dens just 2–3 months after the time of birth. Fish and crayfish exhibited a seasonal fluctuation, with a maximum density of biomass between the end of spring and the end of summer and minimum densities in winter. Water was always flowing in the Pyrenees and Prepyrenees rivers; however, in Mediterranean rivers, important periods of drought were observed, concentrated especially in summer and some winters. Timing of birds corresponded to variation in abundance of food (energy needs) and water resources in space and time. The presence of adequate prey species for the cubs (Ebro's barbel (Barbus graellsii and Barbus haasi) and American crayfish (Procambarus clarkii) in our study area) plays an important role. Interannual variations in food can affect the otter's reproductive cycle and breeding success.

Marine-feeding otters (Lutra lutra) in Norway: seasonal variation in prey and reproductive timing

1993 ◽  
Vol 73 (2) ◽  
pp. 297-312 ◽  
Author(s):  
Thrine Moen Heggberget
Keyword(s):  
Seasonal Variation ◽  
Gadus Morhua ◽  
Prey Species ◽  
Species Group ◽  
Food Resources ◽  
Late Winter ◽  
Published Data ◽  
Lutra Lutra ◽  
Reproductive Timing ◽  
Main Prey

Diet and food resources of marine-feeding otters (Lutra lutra, Mammalia) were studied along the coast of central Norway, where otters breed in all seasons. The fish and crab fauna in the 0–10 m depth zone where otters forage were sampled and otter spraints collected monthly for three years. Results were compared with published data from Shetland where otters breed mainly in summer. Most of the main prey species showed significant seasonal variation in numbers or biomass, which tended to be low in late winter or spring. The variations during the rest of the year were not synchronized between species. The combined density of the main prey species of Shetland otters, which peaked during summer, was low in Norway. This species group, eelpout (Zoarches viviparus), butterfish (Pholis gunnellus) and rocklings (Ciliata sp., Gaidropsarus sp. ), also constituted a smaller fraction of the total catch in Norway than in Shetland.) and bullrout (Myoxocephalus scorpius), constituted a larger fraction of the catch in Norway than in Shetland. Thus the otter's food resources on the Norwegian coast were seasonal, being minimal during the early months of the year, but with no clear maximum season as there is in Shetland. This may explain the differences in reproductive timing in the non-seasonal or autumn and winter species, cod (Gadus morhua.

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.

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.

scholarly journals Gut content analysis of cattle egrets (Bubulcus ibis) in Asam Kumbang Crocodile Park, North Sumatra

2021 ◽  
Vol 912 (1) ◽  
pp. 012105
Author(s):  
E Jumilawaty ◽  
N Namira ◽  
A Anggelicha ◽  
A Hartanto
Keyword(s):  
Content Analysis ◽  
Prey Species ◽  
Prey Availability ◽  
Biological Control Agent ◽  
Food Resource ◽  
Control Agent ◽  
Gut Content Analysis ◽  
Gut Content ◽  
Dominant Group ◽  
Bubulcus Ibis

Abstract Cattle egret (Bubulcus ibis) is a widespread avian species inhabiting a variety of natural and artificial sites. Asam Kumbang Crocodile Park is one of establishments that occupied some portions of B. ibis habitat with no recent information on the food resource and prey availability for the viability of B. ibis. To this aim, we collected 10 random individuals of B. ibis to be sacrificed for gut content analysis of prey species. A total of 19 taxa was found as prey items in the gut of B. ibis with the dominant group from insects (Orthoptera, Scolopendromorpha). The diversity of prey species was categorized as moderate with intraspecific diet variation which formed four guilds that fed on specific taxa namely Group 1 (Haplotaxida, Lepidoptera, Anurans), Group 2 (Blattodea, Coleoptera, Araneae), Group 3 (Orthoptera, Scolopendromorpha); and Group 4 (Dermaptera, Squamata). Oxya chinensis and Oxya velox are important rice grasshopper pests that were also found in the gut of B. ibis reflecting their potential function as biological control agent.

Ecology of gyrfalcons, Falco rusticolus, in the central Canadian Arctic: diet and feeding behaviour

1988 ◽  
Vol 66 (2) ◽  
pp. 334-344 ◽  
Author(s):  
K. G. Poole ◽  
D. A. Boag
Keyword(s):  
Feeding Behaviour ◽  
Prey Species ◽  
Prey Availability ◽  
Optimal Foraging Theory ◽  
Ground Squirrels ◽  
Spermophilus Parryii ◽  
Falco Rusticolus ◽  
Lagopus Mutus ◽  
Spring Arrival ◽  
Average Size

Diet and aspects of feeding behaviour in a population of gyrfalcons (Falco rusticolus) in the Northwest Territories were examined between 1984 and 1986. Three prey species, rock ptarmigan (Lagopus mutus), arctic ground squirrel (Spermophilus parryii), and arctic hare (Lepus arcticus), composed 96.5% of total prey biomass identified. Ptarmigan and hares were taken in May and June of all years (98.2% of biomass). Juvenile squirrels were used extensively in July and August of 1984 and 1985 but not in 1986, when squirrel production fell to almost zero; ptarmigan continued to be the dominant prey species throughout that summer. Because densities of breeding ptarmigan remained relatively constant during the study, but those of juvenile ground squirrels did not, it appeared that gyrfalcons responded functionally to varying availability of prey. Mean weight (250 g) of prey taken by male gyrfalcons was significantly less than the weight (330 g) of prey taken by females. As predicted by optimal foraging theory, average size of prey brought to the nest increased as time away from the nest increased. Conditions of food abundance were observed at most nests, suggesting that the amount of food available during the nestling period was not limiting production. We suggest that annual production is a function of spacing of pairs, which is set during courtship and prelaying, when prey availability is at its yearly low and when males must forage for both members of the pair. The fact that most gyrfalcon pairs initiated laying only after the spring arrival of migrating ptarmigan is consistent with this conclusion.

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