| Summary: | Background. The current climatic trend towards warming and aridization has a
negative impact on amphibian populations on a global scale. Against this background, longterm
monitoring the time frame of life cycle phases and the dynamics of abundance in local
amphibian populations become highly relevant. Territories located at the junction of different
landscape-climatic zones, where general patterns should emerge most clearly, are gaining
great interest in this vein. The purpose of the research is to study the seasonal patterns
of activity and time frames of the reproduction in populations of the Green Toad (Bufotes
viridis) and the Eastern Tree Frog (Hyla orientalis) and also the detection the relationship
of the timing of seasonal phenomena with local climate and observed weather conditions.
Materials and methods. The work was carried out in 2002–2023 in the Karadag State Nature
Reserve. The data about the life cycles of amphibians is based on year-round stationary
observations. To assess the strength and character of the relationship between phenological
phenomena and climatic indicators of the area (according to the data of meteorological station
near Biostantsiya settlement), correlation analysis was used. Results. A generalized
trajectory of populations of two common amphibian species at the beginning of the 21st
century was presented and the data about the phases of their life cycle has been updated.
Some phenological phenomena correlate with climatic parameters at a statistically significant
level; in many cases, a relationship at the trend level was found. For both species, a
shift in the timing of phenological phenomena associated with a change in the moisture
regime of the territory of the Karadag reserve, was recorded. The predominance of little
snow winters and dry springs against the backdrop of rising temperatures has led to the
degradation of spawning reservoirs. The duration of the spring spawning phase has decreased,
but the duration of its “summer” phase, coinciding with periods of heavy rainfall in
May – July, has increased compensatoryly. Conclusions. Despite the flexibility of the time
frame of reproduction in the studied species, aridization of Karadag’s landscapes which has
been continuously increase since the mid-2000s, caused a catastrophic decline in the amphibian abundance. Practical measures for the conservation of anuran populations on protected
territory are proposed.
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