ISSN 1067-4136, Russian Journal of Ecology, 2007, Vol. 38, No. 6, pp. 408–412. © Pleiades Publishing, Ltd., 2007.
Original Russian Text © V.G. Degtyarev, 2007, published in Ekologiya, 2007, Vol. 38, No. 6, pp. 438–443.
After wintering, birds arrive to temperate and high
latitudes in the period when ecosystems are in the
state of transition from winter to summer conditions.
In particular, wetlands in this period are still under the
effect of cryogenic processes (in the coldest regions of
Eurasia, lakes remain ice-covered even in June) and,
hence, are characterized by insufﬁcient abundance
and biomass of hydrobionts, which are the main food
for waterbirds. However, this is only one aspect of the
indirect inﬂuence of winter factors on migratory birds
in the period of their stay in the temperate and Arctic
zones: depending on the degree of winter cooling, this
inﬂuence may vary, having speciﬁc forms and consid-
erable ecological signiﬁcance. This study deals with a
variant of such inﬂuence in which the foraging capac-
ity of wetlands for waterbirds increases after a long
and cold winter.
MATERIAL AND METHODS
Data on the structure and state of wetlands as habi-
tats for waterbirds were obtained in the course of ﬁeld
studies on the Central Yakutian Plain and adjoining
Vilyui and Lena plateaus between 1978 and 2004.
Wetlands were surveyed by a standard scheme,
recording seasonal changes in their characteristics: the
course of ice cover destruction, changes in water level
and shoreline conﬁguration, the state of aquatic and
riparian vegetation, and consequent changes in the
structure of bird habitats. Biotopes in which the birds
foraged were also studied. Permanent foraging sites of
a certain group of birds were examined to determine the
type and state of substrates and the composition and
density of food objects. Such biotopes were identiﬁed
in the course of observations on the seasonal and diur-
nal dynamics of foraging activity and bird distribution
over the water body, including censuses of the traces of
this activity left on silty substrates.
Exposed substrates and shoals (substrates covered
with a thin water layer) were studied with the aid of
Konakov and Anisimova’s biocenometer (Fasulati,
1971) without the bag; i.e., only the frame of this device
was used. This frame (0.25 m
) was forced into the silt
until it rested on the frozen silt layer. Thereafter, inver-
tebrates lying on the surface delimited by the frame
were counted and collected, and the whole amount of
thawed silt within it was removed with a square scoop
and transferred to an individual container. The silt was
sieved through nylon gauze no. 17, and the resulting
benthos sample was analyzed to determine the presence
and approximate numbers of potential bird food
objects, identifying invertebrates at the level of species
or higher rank taxa. A total of 25 samples were ana-
The term “foraging capacity” is used in Karzinkin’s
(1952) interpretation, and terms related to climatology
and permafrost science are understood according to the
Four-Language Encyclopedic Dictionary of Physical
, 1980), with the
term “ice” designating the solid physical state of water.
Effect of Deep Freezing of Lakes on Food Supply
in Habitats of Waterbirds
V. G. Degtyarev
Institute of Biological Problems of the Permafrost Zone, Siberian Division, Russian Academy of Sciences,
pr. Lenina 41, Yakutsk, 677980 Russia
Received January 20, 2006
—The phenomenon of bottom substrate exposure in deeply freezing lakes during the melting of ice in
spring is described. It leads to the formation in the lake of a large temporary biotope—a combination of shoals
and exposed portions of the silty bed—with a high trophic capacity for ducks, shorebirds, gulls, etc. The lake
in such a state is a rich foraging area for nesting and migrating bird populations. This phenomenon, which is
widespread in the Central Yakutian plain, is an ecological manifestation of cryoarid conditions developing in
the plains due to extreme climate continentality.
: waterbirds, food supply, lakes, freezing.