title: Warm springs, early lay dates, and double brooding in a North American migratory songbird, the black-throated blue warbler.
abstract: Numerous studies have correlated the advancement of lay date in birds with warming climate trends, yet the fitness effects associated with this phenological response have been examined in only a small number of species. Most of these species--primarily insectivorous cavity nesters in Europe--exhibit fitness declines associated with increasing asynchrony with prey. Here, we use 25 years of demographic data, collected from 1986 to 2010, to examine the effects of spring temperature on breeding initiation date, double brooding, and annual fecundity in a Nearctic-Neotropical migratory songbird, the black-throated blue warbler (Setophaga caerulescens). Data were collected from birds breeding at the Hubbard Brook Experimental Forest, New Hampshire, USA, where long-term trends toward warmer springs have been recorded. We found that black-throated blue warblers initiated breeding earlier in warmer springs, that early breeders were more likely to attempt a second brood than those starting later in the season, and that double brooding and lay date were linked to higher annual fecundity. Accordingly, we found selection favored earlier breeding in most years. However, in contrast to studies of several other long-distance migratory species in Europe, this selection pressure was not stronger in warmer springs, indicating that these warblers were able to adjust mean lay date appropriately to substantial inter-annual variation in spring temperature. Our results suggest that this North American migratory songbird might not experience the same fecundity declines as songbirds that are unable to adjust their timing of breeding in pace with spring temperatures.
authors.affiliation: Hubbard Brook Experimental Forest, Northeastern Research Station, USDA Forest Service, Newtown Square, PA, USA. aktownsend@ucdavis.edu
authors.forename: Andrea K
authors.initials: AK
authors.lastname: Townsend
authors.forename: T Scott
authors.initials: TS
authors.lastname: Sillett
authors.forename: Nina K
authors.initials: NK
authors.lastname: Lany
authors.forename: Sara A
authors.initials: SA
authors.lastname: Kaiser
authors.forename: Nicholas L
authors.initials: NL
authors.lastname: Rodenhouse
authors.forename: Michael S
authors.initials: MS
authors.lastname: Webster
authors.forename: Richard T
authors.initials: RT
authors.lastname: Holmes
mesh_terms: D025041:Animal Migration; D000818:Animals; D005260:Female; D008297:Male; D009513:New Hampshire; D012098:Reproduction / Q000502:physiology*; D012621:Seasons; D020308:Songbirds / Q000502:physiology*; D013696:Temperature
references.citation: J Anim Ecol. 2009 Jan;78(1):73-83
references.pmid: 18771506
references.citation: Proc Biol Sci. 2009 May 7;276(1662):1619-26
references.pmid: 19203918
references.citation: Proc Biol Sci. 2009 May 22;276(1663):1845-54
references.pmid: 19324765
references.citation: Proc Biol Sci. 2010 Apr 22;277(1685):1259-66
references.pmid: 20018784
references.citation: Nature. 2001 May 17;411(6835):296-8
references.pmid: 11357129
references.citation: Science. 1988 May 6;240(4853):798-9
references.pmid: 3363360
references.citation: Trends Ecol Evol. 2009 Mar;24(3):127-35
references.pmid: 19185386
references.citation: Proc Natl Acad Sci U S A. 2008 Oct 21;105(42):16195-200
references.pmid: 18849475
references.citation: Science. 2000 Jun 16;288(5473):2040-2
references.pmid: 10856216
references.citation: Proc Natl Acad Sci U S A. 2003 Sep 16;100(19):11139-42
references.pmid: 12960365
references.citation: Proc Biol Sci. 2005 Dec 22;272(1581):2561-9
references.pmid: 16321776
references.citation: Proc Biol Sci. 2003 Feb 7;270(1512):233-40
references.pmid: 12614571
references.citation: Proc Biol Sci. 2008 Mar 22;275(1635):649-59
references.pmid: 18211875
references.citation: Oecologia. 1998 Aug;116(1-2):284-292
references.pmid: 28308538
references.citation: Proc Biol Sci. 2011 Mar 22;278(1707):835-42
references.pmid: 20861045
references.citation: Nature. 2003 Jan 2;421(6918):37-42
references.pmid: 12511946
references.citation: Proc Biol Sci. 2003 Oct 22;270(1529):2105-10
references.pmid: 14561272
references.citation: Ecology. 2011 Feb;92(2):450-61
references.pmid: 21618924
references.citation: J Anim Ecol. 2010 Jul;79(4):777-84
references.pmid: 20202013