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Otter Lutra lutra distribution in Poland

100%

Brzezinski M., Romanowski J., Cygan J. P., Pabin B.

Acta Theriologica

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1996

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tom 41

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nr 2

In a field survey of Poland in 1991-1994, signs of otters Lutra lutra {Linnaeus, 1758) were found at 1655 (79.5%) of the 2083 investigated sites. Widespread in most of the country, otters were especially common in the lakelands (N Poland), along the western and eastern borders, and in the Karpaty/Carpathian Mts (SE Poland). Two large areas with only few positive sites were identified in Śląsk/Silesia (SW Poland) and central Poland. Otters inhabit the majority of large rivers in Poland, except some sections of Odra/Oder and Wista/Vistula. The dynamics of the otter population in Poland in recent decades is difficult to investigate, mainly due to the scarce questionnaire data from the sixties and seventies, however, present records suggest that the otter has extended its range, and is no longer an endangered species in Poland.

2

Population analysis of dental anomalies of otters Lutra lutra from Eastern Germany

86%

Hauer S.

Acta Theriologica

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2002

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tom 47

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nr 3

A sample of 1037 skulls of otters Lutra lutra (Linnaeus, 1758) from eastern Germany was analysed for inherent dental abnormalities. Deviations from the normal dental pattern were found in 107 individuals. A total of 150 cases were classified in 5 categories of abnormality. In considering variations from the normal number of teeth, supernumerary (polydonty, 1.7%) was more frequent than missing teeth (oligodonty, 0.9%). In most cases, numerical variations were not connected with phylogenetic background. The most frequent variations were displacement of teeth in the tooth row (6.0%) and deviations of the normal shape of teeth (3.3%). Variations of the local position of teeth occurred in 2.6% of cases. None of these deviations showed significant sex-dependent differences. Furthermore, no regional differences in the frequencies of these anomalies were noticed. Another 459 otters (822 cases) had accessory roots at P2, P3, or P4. These characters were considered as non-metrical traits and used to study epigenetic regional differentiation. The Mean Measure of Divergence segregated the Baltic coast from almost all other regions. Preliminary results of analysis of Fluctuating Asymmetry are presented, using these traits to demonstrate the utility of dental deviations for estimating influences on developmental stability. Generally, it can be stated that the dentition of otters is very stable.

3

Individual differences in spatial utilization of a river-system by otters Lutra lutra

86%

Durbin L. S.

Acta Theriologica

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1996

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tom 41

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nr 2

One female and 2 male otters Lutra lutra {Linnaeus, 1758) were radio-tracked in the River Don catchment, Aberdeenshire, Scotland, between April 1988 and June 1990, and their range use patterns were compared. The males had longer total ranges than the female. The range of the larger male almost completely overlapped with that of the female, but the range of the smaller male was mainly separate from that of the female. The ranges of the 2 males only partially overlapped, with the larger male having the greatest total range, nightly range and rate of travel, and the lowest tendency to revisit areas during the night. The smaller male was relatively sedentary, using two separate core areas, whereas the other 2 otters had single core areas and frequently patrolled their total ranges. As the larger male was sexually active, but the smaller one did not appear to be, it was argued that the need to search for mates could explain some of these differences in spatial patterns. All 3 otters used tributaries more than expected based on the areas within their total ranges. This may be because riparian margins were used in greater proportion than central areas of the channel width.

4

Otter diet in relation to fish availability in a fish pond in Hungary

86%

Lanszki J., Kormendi S.

Acta Theriologica

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1996

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tom 41

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nr 2

The food composition of otters Lutra lutra (Linnaeus, 1758) was investigated in an artificially established fish pond of 12 ha in south-western Hungary between December 1991 and November 1994. In the fish pond fish farming was carried out with the introduction of different species during the first two years of the investigations, while the filling up of the pond with water and its planting did not come about in the third year. The diet of otters was examined by spraint analysis (873 samples). The most important prey of otters was fish amounting 40 to 100%; the variation was due to season, method of farming and density and composition of the fish stock available. There was a close relationship between the frequency of occurrence of different fish species in the otter diet and the amount of fish available to the otters. The correlation coefficients (rp) were 0.56 (p < 0.05), 0.87 (p < 0.0001) and 0.93 (p < 0.0001) in the three years. Fish species that are predominant in the fish pond were the most frequent in the otter diet. Most of the fish eaten were below 50 g, ie 55, 88 and 90% respectively in the three years. Prey fish weighing more than 1000 g were found in scats only in the second year, and in a low proportion (1%). Economically important fish species constituted 33, 9 and 3% of the otter diet in the three years. The economic consequences of otter predation on fish are discussed.

5

Observations on the predation behaviour of the otter Lutra lutra in NE Spain

86%

Ruiz-Olmo J.

Acta Theriologica

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1995

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tom 40

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nr 2

Adult and sub-adult otters Lutra lutra (Linnaeus, 1758) caught and consumed 3.36 prey (fish) per hour (n = 32 captures). This represents 273.8 g of wet mass/h of activity outside the rest sites (10.5-13.1% of the day) and it is enough to get their daily needs. Otters ate the prey without hiding on average (n = 93) 0.46 m from the bank (up to 3.9 m) and 0.25 m above water level (up to 2.05 m). Prey weighing less than 150-200 g were consumed entirely; for this reason prey remains are very rare (except large trout, American crayfish and gravide cyprinid females). Unpleasant tasting or toxic parts and sharp or wide parts of the bones, scales, teeth, claws, heads or leggs in large prey were not eaten.

6

Diet composition of the otter Lutra lutra in the Bieszczady Mountains, south-east Poland

86%

Harna G.

Acta Theriologica

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1993

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tom 38

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nr 2

The diet of the otter Lutra lutra (Linnaeus, 1758) was studied in the Bieszczady Mts (south-east Poland), at four locations situated on the small rivers from October 1987 to June 1989. In ail, 379 samples of spraints were analysed and 1687 animals preyed upon belonging to various systematic groups were identified. Frequency analysis indicated that most of the prey was fish (63.4%) with insects contributing 20.2% and amphibians 14.5%. Among fish the most frequently occurring were Phoxinus phoxinus (frequency - 15.0%), Cottus sp. (14.4%) and Noemacheilus barbatulus (9.0%). Relatively low frequencies were found for Salmo trutta (5.7%) and Thymallus thymallus (3.1%). Percentage analysis indicated that most of the diet comprised fishes (73.2% of biomass) and much less amphibians (26.8%). Among fish species S. trutta dominated (42.4% of all biomass) over Coitus sp. (10.2%) and N. barbatulus (3.9%).

7

Diet of otters Lutra lutra in central Finland

86%

Sulkava R.

Acta Theriologica

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1996

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tom 41

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nr 4

The diet of otters Lutra lutra (Linnaeus, 1758) in central Finland was studied in 1988-1993 by analysing 1506 spraints. The main components of the diet of otters are fish and amphibians. The most important fishes for otters are small (body length mostly less than 15 cm) cyprinids, perches and pikes. The composition of food varies seasonally. In winter amphibians are the most important prey (33.2% of all food). Perches, pikes and cyprinids are important during all seasons, but in winter small sculpins (9.8% of the food) and burbots (8.9%) are also important. In spring the most important prey are cyprinids (38.7% of the food). Amphibians are important, especially in the smallest streamlets (in winter, 68.4% of the food). Otters also eat toads Bufo bufo. In some areas crayfish and mammals are quite important; but for most otters in the study area salmonids, birds, reptiles, insects, moliusks and plants are only occasional food. Most of the otters in the study area live in small forest rivers. In central Finland in winter amphibians and sculpins are of great importance for otters living in small rivers.

8

Detection of otter (Lutra lutra L.) signs in a survey of Central and Eastern Poland: methodological implications

72%

Romanowski J.

Polish Journal of Ecology

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2013

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tom 61

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nr 3

Searching for spraints (excrements) and tracks is widely used for monitoring of European populations of otters Lutra lutra. Data collected in Central and Eastern Poland were analysed in order to evaluate the environmental factors affecting the detection of otter signs during field surveys. At each out of 1111 sites studied from 1996–1998 numbers of otter spraints and tracks as well as distance searched to detect first sign were noted. At each site several environmental variables were recorded to identify factors that may have affected the survey results. The variation in numbers of spraints and tracks found at each positive site was not related to the habitat quality and any other habitat features (including tree and shrub cover, presence of potential shelters) analysed, except the number of tracks was positively related to bridge potential. The distance searched was the most variable indicator of otter occurrence. It increased with the width of river and at sites with few potential sprainting sites, with bridges of poor potential or with no bridges at all, and where many signs of human and domesticated animals activity were noted. The results indicate that detection of otter signs is partially affected by specific elements unrelated to habitat potential and therefore numbers of spraints should not be used as an indicator of otter habitat preference. At a regional scale variation in number of spraints and tracks, as well as distance searched was related to otter occupancy expressed in the form of percentage of positive sites at three study areas. This study shows that measuring the distance searched provides additional indication of otter status at a regional scale and could be used to identify specific habitats where detection of otter signs during surveys is difficult.

9

Fish selection by riverine Eurasian otters in lowland England

72%

Grant K. R., Harrington L. A.

Acta Theriologica

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2015

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tom 60

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nr 3

10

Notes on the technique of the otter field survey

72%

Romanowski J., Brzezinski M., Cygan J. P.

Acta Theriologica

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1996

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tom 41

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nr 2

58%

Kuhn R. A., Ansorge H., Godynicki S., Meyer W.

Acta Theriologica

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2010

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tom 55

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nr 3

211-222

The hair density of adult Eurasian otters Lutra lutra (Linnaeus, 1758) and sea otters Enhydra lutris (Linnaeus, 1758) was analysed using skin samples taken from frozen carcasses. Lutra lutra exhibited a mean hair density of about 70 000 hairs/cm2 (whole body, appendages excepted), the mean individual density ranging from about 60 000 to 80 000 hairs/cm2. The dominant hair type were secondary hairs (wool hairs), the hair coat comprising only 1.26% of primary hairs (PH). Secondary hair (SH) density remained constant over the body (appendages excepted), whereas a few variations in PH density were observed. Neither an influence of the sex, nor a seasonal variation of the hair coat was found, moulting seems to be continuous. Enhydra lutris had a hair density between 120 000 and 140 000 hairs/cm2, the primary hairs representing less than 1% within the hair coat. Hair density remained quite constant over the regions of the trunk but was lower at the head (about 60 000 hairs/cm2 on the cheek). The hair follicles were arranged in specific groups with different bundles of varying size, normally comprising dominant numbers of wool hair (SH) follicles. Invariably there was always a large central primary hair follicle and numerous sebaceous glands between the bundles and principally around the PH follicles. The results are discussed related to possible ecological influences on hair coat density.

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A record of Pseudamphistomum truncatum (Rudolphi, 1819) (Digenea, Opisthorchiidae) in the Eurasian otter (Lutra lutra L.) from Poland

58%

Hildebrand J., Popiolek M., Zalesny G., Pirog A.

Wiadomości Parazytologiczne

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2011

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tom 57

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nr 3

19

The endangered swan mussel Anodonta cygnea (Linnaeus, 1758) is threatened by the common otter Lutra lutra

58%

Kopij G.

Folia Malacologica

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2011

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tom 19

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nr 3

A heavy otter predation on the swan mussel was recorded in early spring in a fish-pond in SW. Poland. Although natural predation was not regarded as a threat to the swan mussel in Poland, it is likely that in areas where the otter (and possibly also mink, raccoon and muskrat) is common the mussel’s populations may suffer heavy losses.

20

Seasonal variations and changes in the diet of southern river otter in different freshwater habitats in Chile

58%

Medina G.

Acta Theriologica

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1998

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tom 43

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nr 3

The diet of southern river otter Lutra provocax Thomas, 1908 was determined from 605 scats collected from four sites in Southern Chile between 1990-1991. Crustacean remains were the most common item found in scats. Crustacean species that were the most common in scats collected from lakes, became less important in the river outlets. Fish remains were all from fish less than 100 mm in length and were found more frequently in scats collected at the river sites than at the lake sites. Differences in the diet between otter's scats collected in lakes and their river outlets may be related to prey availability and vulnerability. Diet was more diverse in river habitats than in the lakes. The diet of southern river otter appears to be closer to that described for Aonyx capensis and Lutra maculicollis in South Africa. The southern river otter is heavily dependent on the abundance of three crustacean species. Differences in the diets observed between lake and their river outlets suggest important differences in habitat conditions. This may have future implications for prioritising habitat protection in the conservation of southern river otter.

Ograniczanie wyników

Otter Lutra lutra distribution in Poland

Population analysis of dental anomalies of otters Lutra lutra from Eastern Germany

Individual differences in spatial utilization of a river-system by otters Lutra lutra

Otter diet in relation to fish availability in a fish pond in Hungary

Observations on the predation behaviour of the otter Lutra lutra in NE Spain

Diet composition of the otter Lutra lutra in the Bieszczady Mountains, south-east Poland

Diet of otters Lutra lutra in central Finland

Detection of otter (Lutra lutra L.) signs in a survey of Central and Eastern Poland: methodological implications

Fish selection by riverine Eurasian otters in lowland England

Notes on the technique of the otter field survey

The river otter [ Lutra lutra L., 1758 ] as a new fur farming animal

Diet of the otter Lutra lutra in Lake Kerkini and stream Milli-Aggistro, Greece

Reproductive plasticidy of the American mink Mustela vison in Belarus

Competition between American mink Mustela vison and otter Lutra lutra during winter

Habitat factors and the presence or absence of otters Lutra lutra in Denmark

Survey of an otter Lutra lutra population in Southern Italy: site occupancy and influence of sampling season on species detection

Hair density in the Eurasian otter Lutra lutra and the Sea otter Enhydra lutris

A record of Pseudamphistomum truncatum (Rudolphi, 1819) (Digenea, Opisthorchiidae) in the Eurasian otter (Lutra lutra L.) from Poland

The endangered swan mussel Anodonta cygnea (Linnaeus, 1758) is threatened by the common otter Lutra lutra

Seasonal variations and changes in the diet of southern river otter in different freshwater habitats in Chile