Table 2 Predictor variables and their explanation used in analysing variation in breeding time

Territory–indicating microclimate

Altitude

Altitude of most frequented nest site at the territory

Distance^a

Distance from the river outlet to the most frequented nest site at the territory

Qmean^a

Absolute mean annual discharge

Catchment–indicating microclimate

Area

Size of catchment area (m²)

Altitude median

Median elevation of catchment (m)

Altitude diff

Altitudinal range of catchment (m)

Bog fraction

Fraction of bogs in catchment, which contribute to flow when saturated

Bog max

Maximum of distance distribution for bogs (m)

Bog mean

Mean of distances (m) between grid-points in the catchment classified as bogs to the nearest river reach, indicating the flow dynamics from saturated bogs

Bog fraction^b

Areal fraction of grid cells with zero distance to the river network for bogs

S mean

Mean of distances (m) between grid-points in the catchment classified as soils to the nearest river reach, indicating the flow dynamics from soils

Soil fraction

Areal fraction of grid cells with zero distance to the river network for soils

L mean

Mean of the distances (m) between points in the river network, a measure of river network complexity

L sd

Standard deviation of distances between points in the river network to the outlet, a measure of river network complexity

L max

Maximum of distance distribution of the river network, a measure of river network complexity

Evotranspiration

Degree-day factor for evotranspiration (mm/day/ °C)

Trigger

Trigger day

Trigger day index for first five-day period above 0 °C

Qspec*

Specific discharge (l/s/km², discharge per area unit)

Qnorm*

Normalized discharge (discharge/annual mean discharge)

T*

Temperature (°C)

P*

Precipitation (mm)

Groundwater*

Dynamic groundwater storage (mm). The part of groundwater storage that fluctuates with runoff indicating hydrological drivers

SCA*

Fraction of the lowest 10% of the catchment that is snow covered

SWE*

Snow water equivalent at the lowest 10% of the catchment (mm)

Ql10*

Indicating whether discharge exceeded 10 l/s or not (indicating extreme drought) in period

Ql100*

Indicating whether discharge exceeded 100 l/s or not (indicating drought) in period

Global climate

NAO*^b

Daily North Atlantic Oscillation Index

NAOcurr

North Atlantic Oscillation Index current year

NAOprev

North Atlantic Oscillation Index previous year

Individual

Age f^a

Female age indicating individual experience and possible age restrictions

Age m^a

Male age indicating individual experience and possible age restrictions

Polyandry

Polyandry status: monogamous or polyandrous brood

Polygyny all

Polygyny status: monogamous, alpha, beta, gamma, successive alpha, and successive beta brood

Polyandry history

0/1 indicator for whether the female has been polyandrous, 1 = yes

Polygyny history

0/1 indicator for whether the male has been polygynous, 1 = yes

polygyny indicator

0/1 indicator for whether the male was detectably polygynous for this brood, 1 = yes

beta polygyny indicator

0/1 indicator for whether the male was detectably polygynous and this wasn’t the alpha brood, 1 = yes

polyandry indicator

0/1 indicator for whether the female was detectably polyandrous for this brood, 1 = yes

male first

0/1 indicator for whether this was the first hatching for this male, 1 = yes

female first

0/1 indicator for whether this was the first hatching for this female, 1 = yes

M novelty

Male territory novelty, 1 = first time for this male in this territory

F novelty

Female territory novelty, 1 = first time for this female in this territory

Other

lintime

Temporal time trend, indicating possible global climatic change

Random effects

Year^a

Annual variation not explained by climatic variables

M id

Male identity (ring number) indicating individual variation

F id

Female identity (ring number) indicating individual variation

Territory id

Territory identity indicating spatial variation not explained by territory and catchment variables