Prezentare la THE FIFTH ANNUAL ZOOLOGICAL CONGRESS OF "GRIGORE ANTIPA" MUSEUM 20-23 November 2013 "Ion Heliade Rădulescu" Amphitheatre of the Romanian Academy, Bucharest, Romania

1. Feeding habits of the Eurasian otters (Lutra lutra, Linnaeus,
1758) living in Putna Vrancea Natural Park
PhD Student: George BOUROȘ
Biologist: Rocío HERMOSILLA GARZÓN
Biologist: Jesús Alberto SÁNCHEZ PARDO

2. Introduction
© Nicole Duplaix
Fig. 11Euroasian Otter (Lutra lutra)
Fig. Euroasian Otter (Lutra lutra)
Eurasian otter is a semi-aquatic carnivore
belonging to the Mustelidae family.
Otter is classified as Near Threatened by the IUCN
and considered Vulnerable by the Romanian
Vertebrate Red Book;
Otter is one of only a few European carnivores
that has developed the ability to actively forage
both in water and on land;
Having knowledge of what individuals eat is one of
the most important aspects of otter ecology, it is a
strong relationship between the availability of food
resources, the distribution and survival of the
species.
Aim of this study is to determine the feeding
habits and the trophic resources, on which depends
the survival of the otter species from Putna Vrancea
Natural Park and Carpathian Mountains.

3. Materials & Methods
Study was conducted on the rivers
and streams belonging to 8 basins
from Putna Vrancea Natural Park;
The park is located in SE Romania,
NE of Vrancea County and covers an
area of 382.13 km², with altitude
ranging from 435 m in the valley of
the Putna River to over 1785 m in
Goru Peak.
Putna River collects all the
streams in the park and forms a
narrow west - east oriented valley.
Most of the flow takes place at the
end of the spring (44%) and early
Fig. 22Study area: Putna Vrancea Natural Park in Romania
Fig. Study area: Putna Vrancea Natural Park in Romania
summer (30%)
The annual average flow of the river Putna at hydrometric station Lepșa, is 1,83 m3/s and in
Tulnici is 4,58 m3 /s;
Riparian woods consist mainly of alder (Alnus glutinosa, Alnus incana) and willow (Salix spp.).

4. Materials & Methods
56 otter spraints were collected from December
2012 to September 2013 from 36 different sites;
For any spraint were noted following
information: date, time, observer, geographic
coordinates, river or stream name, site code and
estimated spraint age;
Spraints were collected in two different periods
of the year, in order to notice variations in the
trophic resource utilization by season;
Fig. 33
Fig.
Sampling
Sampling
sites (left)
sites (left)
Fig. 44
Fig.
Collecting
Collecting
otter
otter
spraints
spraints
(right)
(right)

5. Materials & Methods
Fig. 55Spraints prepared for the analyse
Fig. Spraints prepared for the analyse
Fig. 66Spraints particles identifying
Fig. Spraints particles identifying
Spraints were individually soaked in a metal
container with 1/3 of water and 2/3 of detergent for
1-3 days to a week;
Samples were washed by tipping the contents of
the cup into a 0.5 mm fine mesh sieve;
The spraint particles were then carefully removed
from the sieve and placed in a white plastic tray;
Using different size forceps and needles, any bone
fragments were identified, picked out and sorted into
groups.
The largest vertebra and exoskeletons could be
identified with the naked eye, but for the smallest
was used a magnifier and a microscope (10 X).
The percentage of occurrence of each species was
plotted per spraint and secondly the frequency of
occurrence per prey item was also calculated as:
RFO % = Number of occurrences of a prey group
x100/Sum of occurrences of all prey groups
After being analysed, spraints were dried and
stored in a collection, in plastic tubes which has been
assigned a code and date;

6. Results & Discussion
Relative frequency of occurrence in spraints of various classes of prey species (RFO
%)
From a total of 56 spraints, 53 of them contained the
remains of fish;
RFO% results: 31% fish, 24% amphibians, 21% insects
16% mammals, 3% snails , 3% plants and 2% reptiles.
31 % of all appearances was the fish;
Plundering of amphibian breeding sites during
oviposition in spring;
Reptiles and gastropods low occurrence frequency in
the analysed spraints;

7. Results & Discussion
Percentage (%) of classes of prey species in total spraint analysis
57% fish, amphibians 22%, mammals 15%, insects and
reptiles 3% each, gastropods 0.1% and plants 0.2%.
during winter-spring, fish consumption was reduced by
8%, as compared to the second period when it was 60%;
Amphibians 30% in winter-spring, while during summer
only 16%;
Mammals 12% in winter-spring and 17% summer;
Plants 0% in winter-spring, 0.4% in summer;

8. Results & Discussion
The percentage (%) of occurrence of prey species classes in each of analyzed spraints
% of prey species groups
was calculated for each
spraint, for both study
periods;
some
spraints
were
composed 100% just from a
​
prey class, most of the time:
Pisces, followed by Amphibia,
Reptilia and Mamalia;
For first study period, in a
single spraint could be
identified a consumption of
of varied prey species, unlike
the second study period;

9. Results & Discussion
The analysis of otter feeding habits from Natural Park’s river basins
High altitude river basin samples
Correlation
between the altitude,
river type and
content of the
spraint;
Amphibians :40 %
in Strâmba RB and
mammals in 30%,
while in Ostog RB
amphibians were 45
% and mammals 26
%.
Fish remains were
present in a low
density, 25 % in
Strâmba RB and 27 %
in Ostog RB;

10. Results & Discussion
Low altitude river basin samples

11. Results & Discussion
Fig. 77Reptiles remains
Fig. Reptiles remains
Fig. 99Amphibians remains
Fig. Amphibians remains
Fig. 11 Sorex spp.
Fig. 11 Sorex spp.
Fig. 88Sorex spp. & fish jaws
Fig. Sorex spp. & fish jaws
Fig. 10 Fish remains & jaws
Fig. 10 Fish remains & jaws
Fig. 12 Mammal
Fig. 12 Mammal

12. Conclusions
Most of studies describe otter as
piscivorous, but recent studies suggested that
the otter may be better defined as an
opportunistic predator;
Having knowledge of what individuals eat is
one of the most important aspects of animal
ecology.
The information about the otter diet is
clearly important for otter conservation.
Fishes were prefered by the otters but in
the lack of them, they are able to adapt to
other trophic resources: amphibian, mammal,
reptile, insect etc.
A difference of otter feeding habits was
observed between particular habitats.
Fig. 13 Spraint on aastone in Lepșa
Fig. 13 Spraint on stone in Lepșa

13. Acknowledgements
For Support:
For advices:
Prof. PhD. Dumitru Murariu
PhD. Silviu Chiriac
For training:
For help during field work:
Virginia García López
Francisco Parra Rodriguez
Manuel Menéndez Puertas
Rocío Hermosilla Garzón
Jesús Alberto Sánchez Pardo
For publicity :
...and many more

14. Thank you for your kindly attention!
Questions and Answers!
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