Antipredatory call behavior of lapwing species in an Afrotropical environment

Predation is an important source of natural selection on prey species and has resulted in adaptations such as antipredator vocal signals,which can alert others to the presence of predators and solicit cooperative attack.Although vocal alarm signals of birds have been well studied,they are poorly known in tropical African species.To address this lack of information,the antipredatory signals and responses of two lapwings(Wattled Lapwing Vanellus senegallus and Spur-winged Lapwing Vanellus spinosus)to potential predators were investigated using data collected from focal observation,distance measurements,focal recordings,and playback experiment.The lapwing calls elicited to predators were classified as alarm or mobbing calls based on whether the calls elicited alert behavior or attack from other lapwings.Discriminant linear analysis(DLA)was used to compare the time and frequency parameters of the call types measured in Raven PRO.Also,lapwings’responses to intruders,alert and start distance,time of day,and latency,as well as the effects of flock size and distance to cover were examined.About 48%of all calls was correctly classified by DLA.The best predictors of call type for the lapwings were maximum frequency and high frequency.Both alarm and mobbing calls were elicited by African Wattled Lapwings to dogs and humans.Mobbing calls were elicited to intruders by the Spur-winged Lapwings.Alert distance was positively associated with start distance,and differed between morning and evening in both lapwings.With scarce information from tropical Africa,this study put in perspective vocal and antipredator behavior of lapwing species in Africa.

Is the propensity to emit alarm calls associated with health status?

The production and structure of animal signals may depend on an individual's health status and may provide more than one type of information to receivers.While alarm calls are not typically viewed as health condition dependent,recent studies have suggested that their structure,and possibly their propensity to be emitted,depends on an individual,s health condition and state.We asked whether the propensity of yellow-bellied marmots(Marmota flaviventer)to emit calls is influen ced by their immuno logical or parasite status,by quantifying both trap-elicited and n atural calling rates as a function of their neutrophil-to-lymphocyte(NL)ratio,the presence of a blood borne trypanosome,and the presenee of several intestinal parasites(Eimeria sp.,Entamoeba sp.,and Ascaris sp.).We fitted mixed effects models to determine if the health measures we collected were associated with the probability of calling in a trap and with annual rates of natural alarm calling.Marmots infected with a blood-borne trypanosome were marginally more likely to call naturally and when trapped,while those infected with the intestinal parasite Ascaris were less likely to call when trapped.NL ratio was not directly associated with in-trap calling probability,but males were more likely to call when they had higher NL ratios.Thus,health conditions,such as parasite infection and immune system activation,can modulate the production of alarm signals and potentially provide in formation to both predators and prey about the caller's condition.Playback experiments are required to confirm if receivers use such information.