Fig. 1.

The effect of advance in Arctic phenology on spring schedules and, possibly, population dynamics of godwits. a Onset of spring (dates of snowmelt, emergence of adult crane fly, arrival of godwits on the tundra breeding area and clutch initiation) at Taimyr Peninsula in the Russian Arctic have advanced, whereas dates of arrival in the Wadden Sea have not. b Path analysis revealed that shifts in the dates of the first emergence of crane flies and godwit phenology in the Arctic were mostly driven by changes in the dates of snowmelt. Arrows indicate direction and strength of causal relationships between the variables. Arrows’ widths are proportional to the effect strength (coefficient evidence ratios). Estimates of unstandardized path coefficients λ and their probabilities P(|λ| > 0) (in brackets), from the structural equation model are indicated above the corresponding arrows. Other information on coefficients uncertainty is summarized in Supplementary Table 1. Variable Time represents linear temporal trend. Values for Time are measured over years, while all remaining variables are presented on a daily scale. c After the wintering period in West Africa, godwits migrate to the breeding grounds with a single refuelling stop in the Wadden Sea. The stopover lasts on average 24.5 ± 4 days. Violet lines represent spring migratory tracks of eight godwits equipped with satellite transmitters in 2016, together with the estimated duration of migration paths between Banc d’Arguin and Wadden Sea (3.8 d) and between Wadden Sea and Taimyr (5.5 d), and the two white circles show the only additional stopovers (of 2.5 d, each) on approach to the breeding grounds. d Counts at one of the major wintering areas of godwits at Banc d’Arguin, Mauritania, West Africa, show a decline in population size. The world borders shapefile used to make this figure was downloaded from Thematic Mapping API (http://thematicmapping.org/downloads/world_borders.php), which is available under a CC-BY-SA license. All rights reserved