المفاهيم الأساسية
Rough-legged buzzards exhibit a novel "foxtrot migration" pattern characterized by alternating quick and slow phases of movement during the non-breeding season, driven by environmental factors like snow cover dynamics. This results in a "dynamic non-breeding range" that changes throughout the season.
الملخص
The study investigated the migratory behavior of Rough-legged Buzzards using GPS tracking data. It revealed a previously unknown pattern of migration, termed "foxtrot migration", which is characterized by alternating quick and slow phases of movement during the non-breeding season.
During the quick phases, the birds rapidly traverse unfavorable habitats like the taiga zone. In contrast, the slow phases involve directional and continuous movements through more favorable grassland and cropland areas, driven by changes in snow cover dynamics. This results in a "dynamic non-breeding range" that shifts geographically throughout the season, rather than a static wintering ground.
The authors argue that this foxtrot migration pattern and dynamic range have important implications for accurately mapping species distributions and assessing conservation status. Traditional methods like mid-winter surveys may fail to capture the full extent of a species' non-breeding range. Similarly, declines observed in one part of the range may reflect changes in range dynamics rather than overall population decline.
The study highlights the value of advanced tracking technologies in revealing complex migratory behaviors, which is crucial for understanding the impacts of environmental change on migratory species. Incorporating these new insights into conservation strategies is essential for effective protection of bird populations in the Anthropocene.
الإحصائيات
"Rough-legged buzzards started their fall migration (quick phase) on 28 September (271±11 days) and ended on 12 October (285±11 days)."
"The mean latitude/longitude where the birds ended their fall migration was 55.57±1.92°/49.35±5.63°."
"During the winter, birds continued to migrate at a slower pace down to 49.53±2.01° latitude (on 5 February, 36±40 days) and 34.29±5.11° longitude (on 24 January, 24±47 days)."
"Afterward, during the second part of the slow phase, the birds returned to 55.52±2.63° latitude and 49.79±8.24° longitude to start the spring migration."
"The quick phase was 1415±50 km long, whereas the slow phase (one part) was 1026±55 km, i.e., 389±60 km shorter."
"During quick phase, birds flew for 15±3 days, and one part of slow phase lasted 100±4 days, i.e., 85±5 days longer."
"The migration speed was 104±6 km/day during the quick phase and 12±7 km/day during the slow phase, i.e., about eight times higher."
اقتباسات
"During quick phases, Rough-legged buzzards cross the forest zone, while during slow phase, they migrate within the grassland and cropland zone."
"If birds fly immediately to the southwest and stay there for the whole winter, they would experience snow cover conditions ranging from 1.4±0.2 % in October to 81.1±5.0 % in January."
"If birds stay where they ended the fall migration, they will find themselves in situations with more snow cover (85.2% vs. 99.5%), but more means that snow cover will be close to 100% for several months in this hypothetical situation."