The cowbird is a master stealer that “ steals ” the maternal tending of unsuspecting victim , put down its eggs in the nest of other birdsso that they unwittingly cover and raise chick that are not their own . In a new written report , researchers reveal how , before deciding on which nests to target , cowbirds case the joint like professional crook .
look in the journalBehavioral Ecology and Sociobiology , the inquiry bear on shiny cowbirds and screaming cowbird , which parasitize the nests of mockingbirds and baywings , severally . The study authors used video transcription and radio receiver tracking to follow the movements of these underhanded avian con - artists in the periods just before and after laying their nut .
They reveal that both species of cowbird meticulously plan their crimes by visiting prospective nests so as to keep tabs on their host , building up a retentivity money box of which birds are get ready to lay eggs and can therefore be targeted – a proficiency do it as “ bookkeeping ” .
The crafty cowbird always direct their reconnaissance mission missions before dayspring , using the cover of wickedness to avoid being detect .
Interestingly , screaming cowbirds tend to visit nests about double as oftentimes as shining cowbird . The researchers say this is probably because baywings are much less predictable than mockingbirds in the timing of their nut - egg laying , which mean screaming cowbirds have to supervise their favored host much more close than shiny cowbirds do theirs .
holler cowbirds also continue to check up on baywing nests after they haveparasitizedthem , to verify that the pseudo chicks have not been discovered and ejected by the host . In dividing line , shiny mockingbird do not return to nest that they have laid in , because they always beak jam in the eggs of their hosts in Holy Order to forestall them from hatching , thereby ensuring that the host provides more forethought for the survive impostor chicks .
They therefore measuredly avert all nests that they have place in , to ensure they do n’t accidentally ruin their own eggs .
While this may all seem slightly devious and despicable , it is nothing compared to the ruthlessness of the dark-brown - guide cowbird , which is say to engage in “ Sicilian Mafia demeanor , ” whereby it repeatedly destroys the nest of legion that have ejected its eggs , just out of spite .
