The first time I got into the spring water flooded with water was in cold April. It seems that it was so recently, but how everything has changed around. Then, on the smooth surface of the endless water space, the eye would catch only on a lonely tree. A little closer, in the calm water, the tops of a bare shrub could be seen. The blue sky was reflected in the dark mirror of the water surface, and the whole picture was seen as a single whole. In the reflection, the same clouds, the same sun, slightly darker in comparison with the real ones. Where is the sky, where is the water? Only the marigold pointed with a yellow light to the nearby land of this short-lived reservoir. The water had already subsided and every day, stepping back a little more, left more and more space on the dry land. Even faster than the river cleared the floodplain, plants rose at the edge of the outgoing water. And already in June the floodplain of the river was no longer recognizable. Dense, dense rows of tall grasses hid female snipes, herbalists and teals hatching eggs. The floodplain can be seen from edge to edge, but of the birds you will notice only those that fly over the swaying grassy sea.
The summer sun was scorching without mercy. Warm, rainy May helped create huge hordes of bloodthirsty insects - human misfortune. I reached the floodplain of the Klyazma at noon, when most of the birds were already resting. But this hot day was a complete paradise for bloodsucking insects. It was not so much mosquitoes and horseflies that irritated us, but countless small midges, for some reason selflessly striving to get into the eyes and mouth.
Now I just had to start shooting at the nest of white-winged terns, which had set up their colony in the center of the green floodplain.
I discovered this colony of terns two weeks ago. The birds began to nest under the cover of sedge bumps in the largest, but shallowest lowland, not far from the main river bed. One could get to the colony only in high boots. At that time, terns were only building nests. They carried building material from the banks of the river, and most couples had not yet begun to lay their eggs. Each married couple arranged an artificial platform from the dead parts of aquatic plants picked up on the shore. Considering that the water in this place was above my knee, it is not difficult to imagine how much they had to work to raise the base of their nest building above the water.
I managed to find two nests with full masonry. Immediately surprised by the miniature of their eggs: they were the size of pigeon eggs. And the upper part of the nest was so unusually small that it did not immediately catch the eye, in contrast to the buildings of larger terns and gulls. In those first nests, as, indeed, in the next two others discovered later, there were three eggs each. Only one clutch, consisting of two eggs, first interested me in its uniqueness, until a completely missing third egg was found on an old sedge bump a couple of meters from the nest. Everything was explained simply: probably some predator tried to steal it, but adult terns prevented.
Now, no one was engaged in the construction of nests, and only partners appeared over the nests, replacing their tired of incubating birds. The water subsided, and the nests built by the first began to rise strongly above its level, but now the tall sedge leaves protected the birds, hiding the nests from prying eyes.
White-winged tern belongs to the genus Chlidonias. This is a small bird, about the size of a starling, but due to its loose plumage and long wings, it seems to be larger than its true size. Unlike their larger relatives, river and barnacle terns, insects are more often prey for white-winged terns than small fish. This is why white-winged terns are more likely to hunt over grassy meadows and wetlands than over open water. These noisy, noticeable birds are usually seen flying over a drying floodplain, and not one by one, but as a whole detachment, combing area after area. Every now and then birds descend to the ground, which makes the flight of dozens of birds seem erratic and zigzag, as if butterflies are dancing in the air. In fact, the terns purposefully examine the floodplain and go down, seeing from above something edible for themselves and their chicks. The birds are very light and maneuverable in flight and can easily catch flying insects. Terns carry their prey in the beak, and not in the crop, like seagulls, therefore it is always clear whether the bird is flying with the prey or not.
I don't know how dangerous terns are for the offspring of small birds, but songbirds drive them away from their nests. Terns themselves protect their nests together, quickly gathering over the troublemaker and diving down on top of him in unison. Birds arrive even from a neighboring settlement, located about a kilometer from here. Those who do not attack simply fly in the air with angry cries of "chre-chre", encouraging more cocky and active relatives. For some reason, the battle fervor does not last long, and after ten minutes only those birds fly over the enemy whose nests are very close to this place. The exceptional ability of terns to notice danger from afar is used by ducks in order to calmly rest during the day. Shirokoski, mallards and teal-cracks spend all daylight hours among sedge bumps flooded with muddy water, next to the settlement of white-winged terns, knowing that restless neighbors will warn them about danger in time.
The inconsistency in the choice of places for the nesting colony, so characteristic of the white-winged tern, has long been noticed by people. These thermophilic birds, arriving to us only when warm weather sets in and insects appear in mass, sometimes settle where they have not even appeared for years, and just as suddenly can disappear from these places already next year.
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Photo "White-winged Blackthorn, or White-winged Black Thorn (Chlidonias fabcopterus), Greece" can be used for personal and commercial purposes according to the conditions of the purchased Royalty-free license. The image is available for download in high resolution quality up to 2794x1863.
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Text of the scientific work on the topic “Trophic relationships between the black Chlidonias niger and the white-winged Ch. Leucopterus terns in Belarus "
The main direction of the autumn migration of the bean goose is the south-south-west: 82% of the geese flew between the south and south-west vectors. Of the 17 recorded, only one flock (29 birds) tried to stop for rest in the area of a large floodplain lake, but this was prevented by the shooting of hunters. The rest of the bean flocks flew in transit. There were 8-120 geese in the flocks, on average 33.3 individuals.
The intensity of the autumn flight of the bean goose
Observation period Observation duration, h Geese taken into account
September 11-20 72.5 0
September 21-30 72.5 54
October 1-10 67.5 399
11-20 October 48.5 80
October 21-25 5.0 0
The flight took place fairly evenly throughout the day. More often flocks flew from 9 to 14 o'clock. We judged the presence of a flight at night by the calls of geese. Observations were carried out from 7 a.m. to 2 a.m., with flyby recorded from 7:30 a.m. to 10:30 p.m., i.e. about 15 hours / day For 10 days of mass flight, about 1.5 thousand bean bean flew over a 2 km section of the front.
Russian Ornithological Journal 2020, Volume 29, Express Issue 1896: 1082-1083
Trophic relationships between black Chlidonias niger and white-winged Ch. leucopterus terns in Belarus
Second edition. First published in 1991 *
The material was collected in reservoirs of various types (lakes, reservoirs, fish ponds, swamps). 112 food samples from the black Chlidonias niger and 85 samples from the white-winged Ch. leucopterus terns.
Invertebrates predominated in the food of the black tern - 56 species (98.1% of the total amount of food components). In insignificant
* Naumchik A.V., Petrusenko A.A. 1991. Trophic relations of black and white-winged terns in Belarus II Materials of the 10th All-Union. ornithol. conf. Minsk, 2, 2: 109-110.
Among them were fish - bleak, roach, perch, pike, ide. Invertebrates were dominated by insects (97.9%), of which Diptera (47.6%) predominated; a significant number were Hemiptera (21.0%), Coleoptera (11.1), dragonflies (10.8), and caddis flies (8.7%). Gastropods (0.2%) and spiders (0.1%) were represented singly.
The food of the white-winged tern was also represented almost exclusively by invertebrates (93.3%), and singly by fish (bleak, verkhovka, roach, perch). Most of the food items turned out to be insects (98.0%), Hemiptera (43.1) and Coleoptera (28.7%) predominated; dragonflies (10.9), caddis flies (2.4) and Diptera (6.0%) were represented in a smaller number.
In terms of the biotopic confinement of food objects, the black tern was dominated by polytope (40.8%) and freshwater (39.6%), while meadow elements (11.1%) were found to be smaller in number. The specific abundance of bog, forest, and other inhabitants in both species did not exceed 5.0%. The white-winged tern was dominated by freshwater forms (58.9%); in a much smaller number, meadow (21.1%) and polytope (9.2%) inhabitants were found.
Although the black and white-winged terns live and feed in the same biotopes, the composition of their food is significantly different. The occurrence of Diptera in the first species was about 7 times, and caddis flies - 4 times more than in the second, but half-beetles and Coleoptera were twice, and Orthoptera - 10 times less. Only dragonflies were found to be approximately equal in number. On the example of these species, a certain division of trophic niches can be traced.
In terms of trophic specialization, saprophages (47.2) and zoophages (35.8%) prevailed in food samples of the black tern; phytophages (14.6) and insects with a mixed type of feeding, or mixophages (2.4%), were found in a smaller number. In the white-winged tern, zoophages (69.7%) took the first place, phytophages were represented by a smaller number (21.7), and saprophages (6.3) and myxophages (2.3%) were insignificant. In the food web, the black tern exerts its main influence on saprophages and zoophages, and the white-winged tern - on zoophages.
