Study On Alarm Information Transfer In Three Species Of Passerine Birds

Information communication among animals is very important for maintaining community relationship,individual survivorship and reproduction.Revealing the mechanism and evolution of information transfer of animal signals is a foundation question in animal communication.For birds,bird vocalization is the major means of communication,and they usually produce alarm calls in addition to showing behavioral responses when in danger.However,knowledge of what information contained in the alarm calls,and how the information transmitted are largely unknown.In this study,I focused on three Passeriformes species in conditions of predation and brood parasitism pressure,investigated the information of alarm calls,as well as their transfer mechanism.This study adopt the methods of posing specimens,alarm calls recording and sonograms analysis,playing alarm calls back and behaviors observation.After the analyses of experimental data,we obtained the major results and conclusions as follows:I played back the recordings from barn swallows(Hirundo rustica)in response to a parasitic common cuckoo(Cuculus canorus)dummy(barn cuckoo alarm calls)and a predator Eurasian sparrowhawk(Cuculus canorus)dummy(barn hawk alarm calls)to sympatric and non-sympatric conspecifics.In playback experiments,swallow barns performed stronger responded behaviors to barn sqarrowhawk alarm calls than to barn common cuckoo alarm calls.Which results suggested that swallow barns could distinguish between common cuckoo and sparrowhawk,and their alarm calls could transmit different information to individuals of conspecifics.Conspecifics individuals among different breeding regions could share alarm information of alarm calls.By posing specimens,I observed the response behaviors and recorded the alarm calls of great tits(Parus major)to a sparrowhawk and a common cuckoo.There was no significant difference in behavioral response among great tits when exposed to the dummy of cuckoo and sparrowhawk.But,they differed significantly in alarm calls.Great tits produced more notes per call contained increasing D-type and decreasing I-type notes when responding to sparrowhawk than to cuckoo.Then I played back the recordings from great tits in response to the cuckoo(tit cuckoo alarm calls)and sparrowhawk(tit hawk alarm calls)to conspecifics.In playback experiments,we found that great tits responded more strongly to tit hawk alarm calls than to tit cuckoo alarm calls.This results suggested that great tits may be able to distinguish between common cuckoo and sparrowhawk,and they perhaps convey information in alarm calls by adjusting the number and combinations of notes of a single call type.I divided alarm calls(C-D)of great tits which produced in response to common cuckoo into C and D phrases,then copied these two phrases to construct C and D calls separately.Original calls(C-D),C calls and D calls were played back to male great tits to observe their response behaviors.In playback experiments,male great tits performed scanning behaviour to C and C-D alarm calls,while,they did not perform any special response behavior to D calls.The present study suggested that C and D phrases perhaps have different functions.C phrases perhaps have the function to transmit information about dangers existing around,but,we could not sure what's the function of D phrases which may still need further investigation.I played back the recordings from great tits in response to chipmunk(Tamias sibiricus,nest predator),sparrowhawk,common cuckoo and dove(Streptopelia orientalis)to incubating great tit females.In playback experiments,great tit females performed the behaviours of looking out at the hole of nests or leaving nest to tit chipmunk alarm calls,which responded stronger than to other three alarm stimuli.The results suggested that incubating females could assess the outside conditions and adopt a response behaviors relying on alarm calls.I played back alarm calls from green-backed tits(Parus monticolus)in response to common cuckoo(lager size,tit com-cuckoo alarm calls hereafter)and Asian emerald cuckoo(Chrysococcyx maculatus,small size,eme-cuckoo alarm calls hereafter)to the incubating green-backed tit females.In playback experiments,females responded similar to tit com-cuckoo or tit eme-cuckoo alarm calls,such as looking out at the hole of nests or leaving nest.The results suggested that alarm calls of green-backed tits perhaps do not contain the information about sizes of brood parasites.This study showed that Passeriformes birds' alarm calls have the function to transmit alarm informations.Although three Passeriformes species behaved similarly to different categories of intruders,their alarm calls could transmit relative information about intruders to conspecifics.Sound characteristics,such as note combination types,note number of a call and call rates,might play a role in the process of information transmission.Conspecifics receivers could make a trade-off and adopt appropriate response behaviors after receive informations.