Analysis of otter (<i>Lutra lutra</i>) spraints: Part 1: Comparison of methods to estimate prey proportions; Part 2: Estimation of the size of prey fish

Jacobsen, Lene; Hansen, Heidi

doi:10.1111/j.1469-7998.1996.tb05387.x

Cited by 47 publications

(53 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Nevertheless, the general picture of otter diet drawn by FO is often quite similar to what is obtained by estimating the bulk or the biomass of otter prey (Jacobsen & Hensen 1996;Jedrzejewska et al 2001;Clavero et al 2004;Lanszki & Sallai 2006). The estimation of the bulk of food items may be useful when otters largely rely on prey with a large quantity of indigestible parts, such as crustaceans (Remonti et al 2008).…”

Section: Discussionmentioning

confidence: 80%

Eurasian otter (Lutra lutra) prey selection in response to a variation of fish abundance

Remonti

Prigioni

Balestrieri

et al. 2010

Italian Journal of Zoology

View full text Add to dashboard Cite

In 2001 and 2002 we studied Eurasian otter (Lutra lutra) fish selection in southern Italy by comparing otter diet (805 analysed spraints) with fish availability, estimated by electrofishing. The surveyed river was dominated by cyprinids, particularly by chub (Leuciscus cephalus), roach (Rutilus rubilio) and bleak (Alburnus sp.). Roach and chub were the most common prey recorded in spraints. Otters ate mainly small prey (total length < 90 mm). Chub were widely consumed according to abundance, whilst roach and bleak consumption was not proportionate to their availability. Otters selected roach both in 2001 and 2002 and responded to a decrease in roach availability (-27.3%) by increasing their frequency of consumption rather than switching to an alternative prey. Despite their high abundance, bleak seemed to be markedly avoided by otters. We hypothesized that differences in microhabitat selection may influence the susceptibility of cyprinids to otter predation. The possible effects on fish community were briefly discussed.

show abstract

Section: Discussionmentioning

confidence: 80%

Eurasian otter (Lutra lutra) prey selection in response to a variation of fish abundance

Remonti

Prigioni

Balestrieri

et al. 2010

Italian Journal of Zoology

View full text Add to dashboard Cite

show abstract

“…Carss and Parkinson (1996) suggested that the use of the frequency of occurrence (FO) or of the relative frequency of occurrence (RFO) could produce a biased picture of otter diet. Nevertheless, numerous authors found a highly significant correlation between the FO and the bulk or biomass of otter preys estimated using various methods (Jacobsen and Hensen 1996;Jedrzejewska et al 2001;Clavero et al 2004;Lanszki and Sallai 2006). On the other hand, the use of the FO alone could lead to overestimate the role of those items which are preyed frequently but in small quantity, and to underestimate the importance of larger preys which are captured only rarely (Jenkins et al 1979;Wise et al 1981;Beja 1991).…”

Section: Discussionmentioning

confidence: 95%

Trophic flexibility of the otter (Lutra lutra) in southern Italy

et al. 2008

View full text Add to dashboard Cite

Diet composition of otters (Lutra lutra) was investigated in 2001 by spraints analysis (N ¼ 1323) on five rivers of southern Italy, with the aim of assessing the influence of fish availability, elevation and discharge on the consumption of food resources alternative to fish. Data were expressed as per cent frequency of occurrence (%FO) and per cent volume (%V). The study confirmed the great feeding adaptability of the otter that, in rivers partially interconnected and flowing on a small area, showed a strong fish eating habit in some rivers (Sinni and Mercure-Lao) and a diet mainly constituted by alternative resources in other ones (amphibians in the rivers Cogliandrino and Frido, crustaceans in the River Battendiero). Fish consumption for the five rivers was significantly correlated with fish biomass and with mean summer discharge, while it was inversely correlated with the mean altitude of the five rivers. The lack of a clear seasonality in the consumption of food sources alternative to fish together with the correlation between fish use and fish biomass for each river indicated fish availability as the main factor affecting otter relying to non-fish preys. Otter diet seemed influenced by the characteristics of river habitats (altitude, discharge and consequently fish biomass) more than by summer drought, typical of Mediterranean regions. The %FO and the %V allowed to drawn a similar picture of otter diet. Nonetheless the %V was useful for better illustrating diet variation among the different rivers and we argue that it could be useful in habitats where the otter feeds on preys with different proportions of indigestible remains.

show abstract

“…Other authors have used relative frequency (RF). A discussion about the method's accuracy can be found in Carss and Parkinson (1996), Jacobsen and Jensen (1996), Ruiz-Olmo and Palazón (1997) and Clavero et al (2003). As all the diet analyses were always carried out in the same way, this method was considered appropriate.…”

Section: Sampling Designmentioning

confidence: 99%

Diet diversity and breeding of top predators are determined by habitat stability and structure: a case study with the Eurasian otter (Lutra lutra L.)

Ruiz‐Olmo

Jiménez

2008

Eur J Wildl Res

View full text Add to dashboard Cite

A study on Eurasian otter was conducted in order to establish if feeding ecology and breeding of this European freshwater top predator were affected by the habitat complexity or stability. The work was based on the comparison of contrasting environmental settings. Significant gradients were found for otter diet parameters and breeding, both also changing according to habitat gradient patterns (water capacity and permanence during droughts, habitat stability, and habitat complexity). The otter diet was less diverse in the most stable (and complex) habitats, eating more fish. Otters also breed more regularly in such more stable courses, with more suitable fish availability. The step toward lower habitat stability can put otters in a less advantageous position in front of generalist predators, foraging more frequently outside or in the edge of aquatic ecosystems. Implications for otters and other similar top predator's conservation are discussed.

show abstract

Analysis of otter (Lutra lutra) spraints: Part 1: Comparison of methods to estimate prey proportions; Part 2: Estimation of the size of prey fish

Cited by 47 publications

References 17 publications

Eurasian otter (Lutra lutra) prey selection in response to a variation of fish abundance

Eurasian otter (Lutra lutra) prey selection in response to a variation of fish abundance

Trophic flexibility of the otter (Lutra lutra) in southern Italy

Diet diversity and breeding of top predators are determined by habitat stability and structure: a case study with the Eurasian otter (Lutra lutra L.)

Contact Info

Product

Resources

About