black blue black blue small bird new world family breeding ranges located interior deciduous mixed coniferous forests eastern north_america cooler months islands caribbean central_america rarely found western europe considered non indigenous species black blue sexually adult male black face deep blue white adult female olive brown light yellow predominantly black blue diet seeds winter builds nests thick shrubs nesting sites ground favored species study behavior wild black blue defends territory birds species nesting winter habitats black blue requires large forest areas nesting numbers declining taxonomy phylogeny german naturalist described black blue species latin meaning turning blue black blue new world wood family species originally placed genus recently adjusted member genus members genus based findings recent phylogenetic analysis mitochondrial dna nuclear dna old genus deleted genus appears particularly close relatives species breeds north_america winters caribbean studies observed significant differences terms migratory behavior plumage color northern southern populations breeding range northern population mainly winters western caribbean cuba jamaica southern population usually spends winter eastern islands hispaniola puerto_rico males southern population darker plumage northern population differences led consider separate subspecies recent study united_states reveals significant genetic northern samples michigan new_hampshire new_york states southern populations sample north_carolina study results actually recent population expansion single glacial current populations terms observed northern southern populations occurred recently description black blue measures length weighs adult male white black throat face flanks deep blue immature male similar female olive brown light yellow darker wings tail gray crown brown patches cheek sexes thin pointed bill small white wing patches visible like species colorful plumage spring summer outside breeding season plumage distinctive fall black blue distinguished small white wing patches juveniles brown brownish spots throat breast belly bird song described upward flat distribution habitat black blue migratory species breeds temperate mature deciduous forests mixed coniferous deciduous forest thick species found hilly mountainous regions northeastern united_states southeastern canada late summer tropical wooded habitats migration route black blue observed habitats parks gardens nesting site important foraging site playing role determining habitat black blue black blue open nesting species nests close ground choose protected nesting site risk predation relatively low behavior feeding foraging black blue actively low vegetation catching insects flight area moving mainly eats invertebrates crane flies spiders supplement diet seeds fruit winter males females prefer different foraging sites males usually higher foliage females tend forage lower strata time breeding season influences males forage time feed males come foraging strata females black blue instead canopy large leaves long branches affect foraging behaviors black blue prey difficult thick foliage breeding black blue species breeding season usually begins ends july male black blue attracts female attention singing soft melody follows female foraging searching nesting sites soon female stops rest male wings slightly stretches head forward opens bill faces female female makes displays male wings response male mounts female seconds flies researchers showed black blue prefers reside hardwood forests higher food abundant compared lower density plots high density habitats higher density population age average older composed males females years age black blue uses social cues evaluation choice nesting sites particular post breeding songs given males songs strong temporal males sing beginning peak breeding season songs indicative reproductive success near end breeding season male successfully continues sing male failed reproduce habitat post breeding songs reliable reproductive success particular habitat convey essential information breeding comparison traditional idea direct assessment vegetation structure vocal cue efficient easier obtain revealing advantage social communication survival reproduction female respond post breeding songs directly instead likely rely presence males deciding nesting sites extra pair mating black blue socially species males frequently observed territories males suggesting occurrence extra pair identified study plot new_hampshire results extra pair occurs majority extra pair come males neighboring territories extra pair distant territories local reproductive interaction supported study conducted earlier finds extra pair strongly positively local significant association population level males engage mate guarding period females vulnerable successful extra pair usually stay close social mate singing slowly following mate foraging searching nesting site guarding behavior conflict males pursuit extra pair clear extent male prefer mate guarding extra pair male retention studies shown removal male increases chance extra pair offspring brood suggesting mate guarding reduces extra pair attempts extra pair rate nonetheless eliminated males allowed stay near social mates fertility risk period try explain phenomenon females able manage extra pair mating social mate guarding females reject extra pair attempts males absence male guarding females participate extra pair incorporate better genes offspring social mate likely receive help parental care social mates cheating extra pair costly females possible theory extra pair occurs female organisms select males overall high study suggests alternative selection found female extra pair frequencies overall social mates suggested females choose selective set genes particularly affect offspring sexual selection males differential recognition local songs studied populations northern united_states new_hampshire southern united_states north_carolina response found populations northern black blue responds strongly local songs relatively weakly song southern contrast south responds equally songs north south potential explanation difference female preference northern southern black blue females north likely mate male south necessary northern male respond strongly song southern challenger possible barrier gene flow south north exists barrier reverse female choice male songs likely play role gene flow reproductive isolation eventually lead long believed male black blue reproductive maturation breeding season extra pair mating older males research graves found opposing evidence terms size sperm production directional present birds left larger size right holds true older male body mass ratio nonetheless lower older males older males greater degree directional size birds quality likely females employ age dependent choice favor older males distinguished definitive age specific plumage status threats black blue enjoys large range big population population trend currently increasing species ranked concern iucn habitat threatening black blue tropical areas report discussed impact global climate change population dynamics black blue observation particular effect studied relation survival recruitment migratory bird found years warm oceanic phase associated lower adult survival rate ground jamaica lower breeding habitats new_hampshire united_states lower annual recruitment juveniles breeding grounds factors relatively higher years cold ocean weather food availability abundant long term global warming effect adding black blue population
Black-throated blue warbler