about pelicans on the skadar lake introductionpmcg.co.me/natura-web/natura...

NATURA MONTENEGRINA, PODGORICA 1, 2002, Ia-XIa

ABOUT PELICANS ON THE SKADAR LAKE Introduction Skadar Lake, the biggest lake on the Balkan Peninsula, and the famous fresh water ecosystem in Montenegro, is known for the pelicans. One of the northeastern colonies of Dalmatian pelican (Pelecanus crispus Bruch, 1832) is found on this lake. Pelican is one of the most endangered birds in the fauna of Montenegro. For this reason the pelicans are of especial importance for Montenegro and they have become a symbol of Montenegrin ornithofauna and a stylized pelican is a trade-mark of the National Park “Skadar Lake”. Skadar Lake gives good conditions for survival of pelicans as well as the other marsh birds. The lake is large (370-530 km2, depending on the water level), shallow (maximum depth on the offing is 11 m), with warm water (doesn’t freeze). Vast zone of macrophytic vegetation makes plenty of food for birds, which is why the Skadar Lake is a very important habitat, and winter habitat for birds. The lake also gives suitable conditions for pelican’s nesting, dwelling and nutrition. The first data The first data about pelicans on Skadar Lake are found in the reports and travel-records of the first stranger-politicians and naturalists who have visited Montenegro (Bolica, Finger, Frich). Describing the beauty of Montenegro’s nature they have inevitably mentioned pelicans. But the first scientific facts do not appear before the end of the 19th century. Spiridon Brusina, zoologist from Zagreb 1890.organized a “collector’s” expedition in Montenegro on account of getting acquainted with local fauna and collecting exhibits for the Zoological Museum of Zagreb. Mainly they worked on the seaside, but they also visited Skadar Lake where they have caught pelicans serving as proofs. The period of getting acquainted At that time, the most data about pelicans was collected by famous scientist Ludwig fon Führer during his longtime ornithological work in Montenegro. His data were united by the most famous ornithologist of Balkan countries, curator from Sarajevo, Dr Othmar Reiser in the fourth volume of his famous "Materialien zu einer Ornis Balcanica IV - Montenegro". Here we find out that, in that time, the average number of nesting couples of Dalmatian pelican was proximately 35,and that a similar colony existed on the locality Zogajsko blato near Ulcinj. Furher himself has, during his work, caught and stuffed 18 pelicans, of which 6 are placed in the Terrestrial Museum in Sarajevo. From the colonies of Skadar Lake and Zogajsko blato he has also collected eggs from

ONDREJ VIZI: About pelicans on Skadar lake

20 nests, 6 of which are to be found in the same museum. The question if pelicans were endangered, obviously did not vex them. The period of exploration Begins after the World War II. The first more detailed information about pelicans of Skadar Lake gives Ivanovic (1971), also regarding the nesting and the nutrition of pelicans. But only had the starting of a project "Limnološka istraživanja Skadarskog jezera" in 1972.started the detailed and regular research of pelicans and their life on Skadar Lake (Vizi, 1975, 1979, 1981, 1997.), which with some interruptions continues still.

Nesting of pelicans on the Skadar Lake Pelicans build their nests only on small islands, forming colonies, sometimes great in number. The reason for this is quite clear- on those small islands the pelicans, their eggs and their young are protected from different land predators, mainly foxes, martens, weasels and stray dogs and cats.

Some “arbunos” piled up due to the wind and waves. In this way the “pelican isles” are formed (1973).

“Arbunos” withonly three nests

(1977).

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Natura montenegrina 1/2002 - SCIENTIFIC-POPULAR PART

Pelicans on Skadar Lake also follow this nesting pattern. Nests are built on small islands, made out of accumulated peat and often not bigger than a couple of square meter. On the other hand, those bigger, stony islands placed along the south coast of the lake have never served as a habitat for pelicans mainly because of the nearness of people. Peat islands represent a specific quality of Skadar Lake. Around the locality of Humski zaliv, in the zone of exuberant marsh vegetation grows a specific community of marsh plant called carnation

Pelican’s nests placed on a floating peat island (1974).

grass (Carex maritima) and common rattan. The thick reed is supported by stalks of rattan and forms a firm pillar-like formation about 2,5 m long and 0,5 m thick. Locals call these peat islands "arbunosi" or "ambonosi". During the winter, when the vegetation is gradually dying, the wind and waves pluck off "arbunosi" from the ground piling them up into small floating heaps which are finally blocked in the vegetation zone. Pelicans fortify the island by adding more material (willow branches, dry rattan, etc.), and then they build their nests on them. In conditions of warm Mediterranean climate, fertile peat, extra dunged with pelicans’ droppings, becomes overgrown with rich rattan and is no longer suitable for nesting. Pelicans are forced to search for new islands almost every year.

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Pelicans’ nests are placed on one ore more small islands. The diameter of an average nest is about 1 meter and pelicans usually lay two eggs in it. Sometimes there is only one egg in the nest but there have been nests with three eggs. Opinion that in the nests with three eggs, one egg was “palmed off” i.e. that a female pelican mixed up the nests. The only discovered nest with four eggs indirectly speaks in behalf of this thesis. The information about the size of the eggs, time of incubation and the beginning of the hatching of the young pelicans on Skadar Lake correspond with the data from other localities. The young are usually hatched in the period of 1-3 days, which is why the younglings in the same nest can often be different in size. They are hatched as nidicolns i.e. unfledged and helpless. Two weeks later they reach the size of a bigger hen and are covered with gentle gray fluff. When they are about one month old their feathers start to grow. They are able to fly already after two months but they remain close to the colony until fall.

Just hatched, completely helpless youngling.1973

The first breadth.Pelican sits on

eggs 40-42 days(1975).

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A 20 day’s old pelican youngling. By this stage youngling is safe from natural

enemies (1987). Nutrition of pelicans The research of the nutrition of pelicans on Skadar Lake gave us some interesting data. The research was done on the fish that is being brought to the younglings in the colony. The habit of younglings, intimidated by the explorer, to vomit eaten fish in order to make it easier for them selves to move, has considerably simplified the research. Results of the first phase of research are given on graphic No.1. Domination of the rudd (Scardinius erythrophthalmus scardafa) by number and weight is obvious. The second very important species of fish in nutrition of the young is roach (Rutilus rubilio). Both these species belong to the fish of less economic importance on Skadar Lake. Percentage of important fish like eel (Anguilla anguilla) and bleak (Alburnus albidus arborella) is very low. A very interesting fact is that, in this phase of research, the presence of economically important species as carp (Cyprinus carpio) and many other economically significant fish from the lake has not been observed. The research of nutrition has later been continued though irregularly. Again the discoveries were very interesting. Since 1975 when it was first spotted in Skadar Lake, the introduced species crucian carp (Carrassius auratus gibelio) has grown in number so much, that it has completely supplanted rudd and today it is the most represented fish in pelicans’ young nutrition, in number and especially in total weight, for pelicans catch proportionally big crucian carps. During this period it has been observed minimal presence of carp and mullet (Mugil cephalus). Percentage of other fish remained the same as in the

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earlier research. From above mentioned it could be concluded that pelicans do not jeopardize the fishery on Skadar Lake. Opposite to the local belief that pelicans feed only on carp, that is exactly the fish the least present in their nutrition. By feeding on economically insignificant fish, pelicans actually help restore the relation (which has already been disturbed) between these two categories of fish.

Pelican’s young have a lot of enemies: a youngling killed by hooded crow (Corvus

cornix) (1974). Enemies of pelicans The dying of pelicans on Skadar Lake is very frequent and only a small number of young lives to grow up. The reasons for this are both, natural and anthropogenic. The most important natural reason is the weather. Skadar Lake is situated in the Mediterranean climate zone and is known by heavy precipitations during the cold period of the year with two well-marked maximums- in autumn and in spring. Sometimes the nesting of pelicans is disturbed by heavy spring rain and then the colony is flooded, and eggs, part or all of them are destroyed (as it happened in 1975). It had also happen that the wind was so strong that it turned over the whole peat island, and in 1989 all nests and the eggs were destroyed by hail. The natural causes of destruction of pelicans are also crows and magpies that destroy eggs or just hatched youngling. This factor must by all means be

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connected with the most important anthropogenic factor- disturbance. People often visit pelican colonies mostly out of mere curiosity. Alarmed pelicans leave the colony and it becomes accessible to crows. If pelicans are calm and undisturbed, crows and magpies can’t do them much harm. Besides, disturbance increases the percentage of eggs that haven’t been hatched and the death rate of just hatched younglings. Though there was no evidence that eggs were being taken from the nests, a certain number of eggs had been missing without any explanation.

A sketch of Crni Žar with marked position of Dalmatian pelican colonies

in years of investigation. Graphic No.2 shows the success of pelicans’ nesting on Skadar Lake in relation

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with the total number of built nests. It can be seen that, even in the “good” years, the efficiency of nesting has been very low, which tells us that, even at that time the population has been standing at the edge of survival. The fishermen of Skadar Lake in principal preserve pelicans, and the number of killed birds is not great when they are in question. The real trouble is with irresponsible hunters who, in the lack of control, occasionally shoot at grown up pelicans, and have, in the period of this research, killed four pelicans. During the same period two pelicans died of infections provoked by swallowed fish-hooks (‘pari’) that are used for catching eels, and three pelicans that have been hurt in this way, have been discovered on time and rescued. The causes of death of four grown up pelicans have not been cleared up. “The golden age” During the exploration, the ninety-seventies have been marked as the most successful years for survival of pelicans on Skadar Lake. In that period we had the greatest number of nests and successfully raised young. The 1977 was especially good, for in this year the number of built nests reached 52 (including subsequent hatches), and the number of eggs was 102, while the number of successfully raised younglings was 46 (graphic II). It seemed that the population of pelican on Skadar Lake was about to fully recover. But the very

next year was a complete disaster. Even though the number of nests in this year was greater than the year before, only eight younglings were added to the already existing population. The combination of the above mentioned causes of

“The golden age”: one of 6 floating peat islands with nests (1977).

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destruction took its toll. Ever since, the pelican population has been gradually loosing the battle for survival. The number of nests has been constantly decreasing and in ninety-eighties we’ve had our first “dry years” without a single nest built. The pelican moving on the island Grmozur, near the small town Virpazar in 1991 gave hope. It is a small, stony island, with enough space and shelter and it can’t be flooded. Unfortunately, it is too near to human habitats, and because of too much disturbance, pelicans left this island after only two years of nesting there. Ever since, the staggering of this population has continued, and today, we are no longer in position to say that the Dalmatian pelican represents a regular nesting bird on Skadar Lake.

Pelicans on Grmožur island (1992).

What is to be done? Beside the above mentioned, for one of the main reasons why the pelican population is in decrease we take the lack of nesting space. That is, by all means, a consequence of eutrophyzation of the lake. Liquid waste from several bigger towns in Montenegro flows into the Skadar Lake, practically without filtration. The remains of mineral fertilizers that are used a lot in the agricultural hinterland of the lake, through porous ground also get into the lake easily.

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The result of this is increased swelling of macrophytic vegetation on Skadar Lake, and so in the zone where pelicans nest. Almost entire space of Humski zaliv is today overgrown with a thick cover of willow, rattan, water lily and water chestnut. Thgere is practically no clear water. This diminished the effect of wind during the winter; the undulation is lessened so there are no conditions for inception of peat islands (arbunos). Pelicans simply have nowhere to nest.

Once a regular sight, today a rarity: the flock of pelicans on Skadar Lake (1973).

The increasing presence of people on the lake, and greater number of powerful motor- boats (though in the NP “Skadar Lake” only the usage of engines to the intensity of 4 KS is allowed), also has a very inauspicious effect on pelicans. All this brings up the final question: Is it possible to save the pelicans on Skadar Lake? By using foreign experience, with a complete data about the conditions on the lake, the experts from the Natural History Museum of Montenegro in collaboration with NGO “Center for preservation and studying of birds” have created a program for saving pelicans. The point of this program is to install rafts for nesting, which would, anchored on the suitable locations, enable recovery, or even significant increase of the pelican population. Beside that, this program enables the development of ornithological, and the so-called “eco” tourism. It is possible to organize the rounds for visiting the colonies and observing pelicans, from safe distance of course. It is expected that the program should be financed in 2002 so that by 2003 pelicans would have at least two rafts for nesting, as well as the special masked cabin for

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observation. This would mean a brand new chance for Dalmatian pelicans of Skadar Lake.

Though rather big these birds are great flyers: pelicans in the sky (1973).

Photo: Documentation of the Natural History Museum of Montenegro Photographer: Ondrej Vizi The literature used: B r u s i n a S. (1891): Beitreag zur Ornis von Cattaro und Montenegro.-Ornithol. Jahrb., 2 (1): 1-27, Hallein; F i r e r Lj. (1894): Jedna godina ornitoloških izučavanja u Crnoj Gori. -Glanik Zemaljskog muzeja u Bosni i Hercegovini, 6: 543-608, Sarajevo; I v a n o v i ć B. (1970): Neka ornitološka zapažanja na Skadarskom jezeru. - Larus, 21-22: 137-160, Zagreb; R e i s e r O. und L. F ü h r e r (1896): Materialien zu einer Ornis Balcanica IV. Montenegro. - Carl Gerold's Sohn, Wien; V i z i O. (1975): O gnežđenju pelikana kudravog (Pelecanus crispus Bruch, 1832) na Skadarskom jezeru i problem njegove zaštite. -Glasnik. Republ. zavoda zašt. prirode-Prirodnjačkog muzeja, 8: 5-13, Titograd; V i z i O. (1979): New data on breeding of Dalmatian Pelican, (Pelecanus crispus Bruch, 1832) on Lake Skadar. - Glasnik. Republ. zavoda zašt. prirode-Prirodnjačkog muzeja, 12: 125-139, Titograd); V i z i O. (1981): Dalmatian Pelican of Lake Skadar. - Biota and limnology of Lake Skadar, Karaman G.S. and Beeton A.M. eds. Ttitograd; V i z i O. (1997): Crni žar - nova kolonija močvarnih ptica na Skadarskom jezeru. - Zbornik radova CANU "Prirodne vrijednosti i zaštita Skadarskog jezera". Naučni skupovi, knjiga 44: 309-320, Podgorica. V i z i O, & V a s i ć V.(1980): Istorijat ornitoloških istraživanja Crne Gore sa bibliografijom. - Glasnik. Republ. zavoda zašt. prirode-Prirodnjačkog muzeja, 13: 33-55, Titograd;

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