Winter habitat use does not influence spring arrival dates or the reproductive success of Yellow Warblers breeding in the arctic

Winter habitat use can influence the breeding success of migratory songbirds in temperate regions due to its impact on bird condition and breeding phenology. How such carry-over effects vary with latitude is unknown. To address this question, we examined how winter habitat use, inferred from δ13C and δ15N signatures in winter-grown feathers, influenced the breeding phenology and productivity of Yellow Warblers (Setophaga petechia) at the extreme north of their range in the Canadian arctic (68°N) and compared this population with midlatitude Yellow Warbler (51°N) and American Redstart (Setophaga ruticilla; 44°N) populations reported in previous studies. In the arctic, we examined male arrival dates, female clutch initiation dates and the relationship between these timing variables and the number and quality of offspring produced within the season. In contrast to warblers breeding at midlatitudes, we find no support for an impact of winter habitat use on breeding phenology or productivity. Male arrival dates and female clutch initiation dates in both young and older individuals were not correlated with isotopic signatures acquired on the wintering grounds. Males with enriched δ15N signatures paired more rapidly after arrival, indicating a possible relationship between winter habitat use and condition. This relationship did not enhance annual productivity for these individuals, however, as the negative relationship between breeding phenology and reproductive success in our arctic population was significantly weaker than among Yellow Warblers breeding further south. This reduction or absence of timing effects on productivity in the north effectively removes one pathway through which carry-over effects can act.