small family distributed northern pacific species feeds diving deep waters eating variety small marine animals nests dense colonies million individuals breeds mixed species colonies smaller species known sexual ornaments found males females include colorful plumage forehead crest striking scent recalling citrus fruit loud trumpet appear evolved sexual selection total population million half north_america general considered concern population faces additional threats predation oil taxonomy identified german zoologist named genus includes species subspecies family consists species including genus description measure length wingspan weigh reddish orange yellow tipped bill yellowish white white eyes ears bodies wings tails primarily dark grey legs feet grey claws black males females similar females slightly smaller curved bills additionally slightly smaller known forehead black forward curving feathers forehead highly variable narrow forward curving feathers average crest feathers variable length millimetres bright orange bill curved plates like forehead features vary widely populations recognized primarily characteristics breeding season crest group feathers located head eyes second social odor produce breeding season described like odor originates tiny feathers located small patch skin shoulder blades winter plumage bills smaller dull yellow lack plates crest reduced juveniles similar winter adults crest bills smaller colored dull brownish yellow juveniles days reach adult size habitat distribution found northern pacific_ocean particularly prevalent non breeding winter months russian island travel breeding locations islands late spring summer habitats consist slopes boulder fields lava flows sea cliffs found species daily basis circle meters sea breeding colonies triggered disturbances predators posing threat behavior ecology diet primarily forage deep waters areas closer shore large flocks little known winter suggested feed variety marine invertebrates diet consists mainly known eat fishes dive surface water catch food behavior described underwater flight breeding parental care breeding season begins mid ends mid august nesting sites rocky coast breed dense colonies million birds nesting sites close proximity little meters nests high degree adults high degree site fidelity year mating occurs sea males organ males females successful mating mate choice mutual females final choice breeding partner highly social breeding season pair formation pair formation breeding year population having extra pair partners continue self advertise birds advertising behavior linked extra pair mating suggested continuation behavior allows birds find pairs breeding season birds remain partner subsequent breeding season sexes invest highly parental care parents share equally single egg raising chick sexes align parental investment theory care mutual arise sexual selection unique use optical vocal signals mating behavior complex closely related species general evolutionary mechanisms proposed address origin elaborate display traits mating signals males general runaway selection fisher theory runaway sexual selection explains flamboyant traits males resulting genetic ornamental traits mating preference ornaments model mating preferences spread arbitrary traits carry benefits fitness sexual selection good genes hypothesis second mechanism good genes handicap processes mating preference focuses ornamental traits reflect health viability individual expressing good genes convey genetic benefits offspring proposed handicap hypothesis suggests individuals ornamental traits good fitness reflect individual success spite traits sensory exploitation proposed mechanism sexual selection sensory exploitation results mating preferences arise natural selection inherent sensory occur result display trait exploits pre existing sensory bias ornamentation visual ornaments asserted dominance regards claimed display area crest length males females existence traits indicative intense sexual selection sexes large adults sexes receive higher levels sexual interest displays opposite sex compared smaller larger likely obtain mates form pair bonds earlier based divorce rate mortality half individuals find new mate year female crest length primary factor male mate switching years variation displays populations ornaments consistent expression individual time furthermore little sexual evidence condition dependence studies survival neutral studies offer functional purpose ornaments study suggests link habitat complexity facial facial helps individuals navigate complex underground high density nesting sites expected impose selective pressures sensory mechanisms vocal ornaments wide variety single complex calls billing defined pair courtship mutual vocal display crucial successful pair formation male female partners acquainted trumpet calls common advertising calls represents complex vocal sequence linked specific visual display individuals calls differ duration frequency calls primarily performed males seen females particularly strong widowed females calls stay stable year year individuals specific calls associated maintenance long term social bonds pair mates neighbors suggests trumpet calls short term long term individual recognition recognition neighboring individuals calls energy expenditure aggressive displays prevents conflict neighbors trusted individuals dear enemy phenomenon ornaments distinctive citrus like plumage odor scent released feathers upper individual threat billing displays cloud scent released encourages display display birds fully insert half open bill plumage display occurs absence obvious aggression important pair formation sexes strong odor attracts individuals display odor increase breeding season highlighting association courtship mate selection scent act scent found conservation status according concern global population estimated million individuals north american population estimated million birds accurate assessment number birds difficult surface colony nearby sea form small proportion variable poorly understood population greater concern population high predation rats escaped fishing vessels harbor main predators arctic fox common reported caught oil collisions light sources pose additional risks alaska hunting species books field guide birds north_america 6th edition isbn harrison peter isbn del handbook birds world vol isbn guide birds isbn websites
Crested auklet