Examinations and plans
to optimise the conditions of captivity
of European Otters (Lutra lutra) and
Asian small-clawed Otters (Aonyx cinerea)


Staatsexamensarbeit, betreut durch Prof. Dr. Norbert Rieder, Uni Karlsruhe


The principle aim of the present thesis is to acquire some helpful information for zoo architects in

designing optimised enclosures for European Otters and Asian small-clawed Otters. As a rule

architects don’t have profound knowledge of the ecology and ethology of otters. The first chapter

of the paper points out these aspects. By examining and compiling the available literature the

following questions are answered: What are the morphological and physiological particularities of

the two otter species? Where are their spreading areas? What are the distinguishing features of

their habitats? What is their natural behaviour? etc.

The second chapter imparts knowledge of the current keeping of otters. In order to deal with this

problem the author examines the studbook and articles in technical journals about reproduction,

breeding, nutrition and diet. The results are for example that shallow waters with a depth of max.

0.15 m seem to be an important necessity for mating and teaching the young cubs in swimming; or

that male Asian small-clawed Otters help in rearing the cubs, so that a well structured enclosure for

separating the male is not absolutely necessary (in contrast to the European Otter).

In order to analyse the behaviour of captive otters, especially the data of activity from 1989 to

2000 of European Otters in the Zoo Hoyerswerda (Saxonia) are evaluated. The four main results

are: 1. - The feeding time determines the time of highest activity. 2. - Otters prefer underwater

entrances, especially in daylight. 3. - The otters in the Zoo Hoyerswerda seem to have two mating

seasons in May and December. 4. - Otters mainly use the (unheated) pool in summer from June to


After having interpreted and concluded these results, the next chapter presents seven enclosures for

Lutra lutra (Görlitz, Hoyerswerda, Köln, Krefeld, Leverkusen, München, Osnabrück) and four

enclosures for Aonyx cinerea (Braunschweig, Cottbus, Dresden, Köln) inter alia with photos,

architects and ground plans. The author visited nine of them, send questionnaires to the two others

and interviewed the zoo keepers and directors to get suggestions and recommendations for

optimised enclosures.

The previously acquired knowledge of the biology of otters was finally combined with the

knowledge of existing enclosures so that several recommendations could be made about size,

structure, sleeping and breeding boxes, entrances and fence. For example: indeed Asian small-clawed

Otters are more terrestrial than other otter species, but they are not afraid of water and also

use deep waters; the length of the banks is more important than the total size or the water-land-ratio;

the change of different requisites on the small area is decisive for the quality of an enclosure.

Finally the author discusses whether the European Otter or the Asian small-clawed Otter is more

suitable for German and Middle European zoos. Corresponding to the main four duties of zoos –

conservation, research, recreation and education – advantages and disadvantages of each otter

species are discussed so that the zoo direction could carefully consider the different arguments and

make a decision on its own.

Altogether it has 110 pages with 48 figures and is written in German language. For the printed version I demand EUR 30,00, for the digital version on CD (*.pdf and/or *.doc) EUR 20,00 (together EUR 45,00).
So if you are interested in purchasing my dissertation, please contact me via e-mail or at the undermentioned address.
Tobias Laengle
University of Karlsruhe
Institute of Zoology I
Kornblumenstr. 13
P.O.B. 69 80
D - 76128 Karlsruhe

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