This document analyzes and compares the diet of Eurasian otters in two habitats in Romania. Fish make up about half of the otter's diet in both areas. Mammals, frogs, and crayfish are also important food sources. The study found some seasonal variations in diet between the sites and identified top predators like otters as important for conservation of aquatic ecosystems.

1. Comparative diet analysis of the eurasian otter
(Lutra lutra, Linnaeus, 1758) in two different habitats:
Putna - Vrancea Natural Park and Lower Siret Valley
Natura 2000 Site, Romania
PHD. STUDENT BOUROȘ GEORGE

2. “
”
There are no prizes for
answering: otters eat fish.
Paul Chanin, 2013
What else do they eat?
Does the diet vary during the year?

3. Introduction
 The Eurasian otter is an endangered semi-aquatic carnivore belonging to the
Mustelidae family and is protected by international legislation;
 Lutra lutra is classified as ‘Near Threatened’ by the IUCN and considered
‚vulnerable’ by the Romanian Vertebrate Red Book.
 The diet of the otter in Romania is poorly known.
 The otter is one of only a few European carnivores that has developed the ability to
actively forage both in water and on land.
 The Eurasian otter uses as habitat a wide range of ecosystems: highland and
lowland lakes, rivers and streams, as well marshes, riparian forests, delta and costal
areas. All this habitats determine a high variability of the food items that compose
the otter’s diet.
 The purpose of this work is to compare the otter’s diet composition in two different
study areas of SE Romania, describing possible
differences through seasonal diet composition.

5. Study area
The Natural 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 in the central part of the park. Most of the flow
takes place at the end of the spring (44%) and early summer (30%).
The Natura 2000 SCI and SPA Lower Siret Valley is located in the north-eastern
part of the Romanian Plain, along the riverbed of the Siret
river, in its sector between cities Adjud and Galati.
The area of SCI is 250.81km² and of SPA is 364.92km² with an altitude
ranging from 0 to 302 m.
The site is dominated by a vegetation characteristic to the riparian
mixed forests, strongly influenced by the existence of some branches
of Putna and Siret rivers.
Lepsa river
Siret river

6. Materials & Methods
174 otter spraints were collected from December
2012 to July 2014 from Putna-Vrancea Natural Park
(n=118 samples) and Lower Siret Valley Natura 2000
Site (n=56 samples);
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 all year round, in order to
notice variations in the trophic resource utilization by
season;

8. Materials & Methods
Spraints were individually soaked in a metal container containing one third water and two
thirds detergent for 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).
Soricinae jaw Cyprinidae jaw Insectivora paw Fish eye

9. Materials & Methods
The percentage of occurrence of each prey group was plotted per spraint using a comparison
chart for estimating percentage composition.
Also it was calculated the relative frequency of occurrence (RFO) per prey item and
percentage frequency of occurrence (PFO) using the following formulas:
RFO % = Number of occurrences of a prey group x 100/Sum of occurrences of all prey groups
PFO % = Number of spraints containing a particular prey group x 100/ Total number of spraints in
sample
After being analyzed, feces were dried and stored in a collection in plastic tubes which has
been assigned a code and date;
Salmonidae jaw Natrix vertebrae Feathers Crayfish eggs

10. Results & Discussion
PERCENTAGE OF OCCURRENCE
Based on comparison chart for estimating spraint percentage composition.
22,476 %
56,088 %
17,724 %
1,756 %
0,261 %
2,169 %
0,027 %
Amphibia
Pisces
Mammalia
Insecta
Gastropoda
Reptilia
Plantae
2,839 %
36,665 %
12,143 %
0,417 %
0,017 %
0,089 %
1,100 %
32,590 %
14,135 %
Amphibia
Pisces
Mammalia
Insecta
Gastropoda
Reptilia
Plantae
Aves
Crustaceea
Putna Vrancea Natural Park Lower Siret Valley

11. Results & Discussion
100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%
PERCENTAGE OF OCCURRENCE plotted per spraint
Putna Vrancea Natural Park
Amphibia Pisces Mammalia Insecta Gastropoda Reptilia Plantae

12. 0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Excrement 1
Excrement 2
Excrement 3
Excrement 4
Excrement 5
Excrement 6
Excrement 7
Excrement 8
Excrement 9
Excrement 10
Excrement 11
Excrement 12
Excrement 13
Excrement 14
Excrement 15
Excrement 16
Excrement 17
Excrement 18
Excrement 19
Excrement 20
Excrement 21
Excrement 22
Excrement 23
Excrement 24
Excrement 25
Excrement 26
Excrement 27
Excrement 28
Excrement 29
Excrement 30
Excrement 31
Excrement 32
Excrement 33
Excrement 34
Excrement 35
Excrement 36
Excrement 37
Excrement 38
Excrement 39
Excrement 40
Excrement 41
Excrement 42
Excrement 43
Excrement 44
Excrement 45
Excrement 46
Excrement 47
Excrement 48
Excrement 49
Excrement 50
Excrement 51
Excrement 52
Excrement 53
Excrement 54
Excrement 55
Excrement 56
Lower Siret Valley
Amphibia Pisces Mammalia Insecta Gastropoda Reptilia Plantae Aves Crustaceea
Results & Discussion
PERCENTAGE OF OCCURRENCE plotted per spraint

13. Results & Discussion
Relative Frequency of Occurrence (RFO)
Putna Vrancea Natural Park Lower Siret Valley
24,9 %
34,8 %
18,6 %
15,2 %
1,6 %
1,6 %
2,9 %
Amphibia
Pisces
Mammalia
Insecta
Gastropoda
Reptilia
Plantae
36,1 %
8,5 %
10,4 %
0,9 %
8,6 %
0,9 %
24,8%
9,5 %
5,7 %
Pisces
Mamalia
Insecta
Gastropoda
Reptilia
Plantae
Aves
Crustaceea
Amphibia

14. Results & Discussion
Percentage Frequency of Occurrence (RFO)
63,5 %
88,9 %
47,4 %
38,9 %
4,2 %
4,2 %
7,6 %
Putna Vrancea Natural Park
Amphibia
Pisces
Mammalia
Insecta
Gastropoda
Reptilia
Plantae
67,8 %
16,1 %
19,6 %
1,8 %
16,1 %
1,7 %
46,4 %
17,8 %
10,7 %
Lower Siret Valley
Pisces
Mamalia
Insecta
Gastropoda
Reptilia
Plantae
Aves
Crustaceea
Amphibia

15. Results & Discussion
The seasonal variation of otter’s diet
Putna Vrancea Natural Park Lower Siret Valley

16. Results & Discussion
The altitudinal variation of otter’s diet
In the Lower Siret Valley the difference in
altitude is not high so I could not identify a
correlation between altitude and
Putna Vrancea Natural Park consumption of prey species.

17. Conclusions
 The dietary study reveals that fish (49,8 %), frog (16,1 %), mammals (15,9 %) and crayfish
(10,5 %) are the main food items consumed by otters, followed by: birds (4,5 %), reptiles
(1,5 %), insects (1,3 %), mollusks (0,02 %) and plants (0,5 %) showing a seasonal variability
in Putna Vrancea and Lower Siret Valley.
Otter can serve as flagship species to
raise awareness for conservation of
aquatic ecosystems in many areas by
its function of top predator.
Otters are widely distributed predators
in Romania and could be used as
“umbrella” species in every freshwater
habitat, in order to ensure the
conservation of all prey species that
compose its diet.

18. Acknowledgements
For Support:
For advices & coordination:
m.c. Acad. Dr. Dumitru Murariu
Dr. Silviu Chiriac
For training:
...and many more
For help during field work:
Teodora Sin
Virginia García López
Francisco Parra Rodriguez
Manuel Menéndez Puertas
Rocío Hermosilla Garzón
Jesús Alberto Sánchez Pardo

19. RomaniaLutra
http://romanialutra.wordpress.com/