![]() ![]() Japanese great tit parents ( Parus minor) produce distinct alarm calls when confronted with three of their main nest predators 15, 26, 29. Similar Carolina chickadees ( Poecile carolinensis) produce more ‘chick” and fewer ‘dee” notes in the presence of a larger, low-threat predator, whereas smaller and higher-threat predators elicit fewer ‘chick’ and more ‘dee’ notes 28. Black-capped chickadees ( Poecile atricapillus) produce calls with more D notes and decrease the duration of the first D note as well as the time between the first and the second D note, when confronted with smaller and more dangerous predators 16. Tufted titmice ( Baeolophus bicolor) increase the total number of D notes per time unit towards more threatening predators 24. Some species use only one of these possibilities and others a combination of some or even all ways, whereby more dangerous predators usually elicit a stronger response 23, 27. Information about a predator can be encoded by an increased call intensity, a variation in syllable number, syllable duration or call type. Paridae species do not only transmit information in their calls about the presence of a predator, but also about its threat level 23, 24, 25, 26. In birds, the mobbing behavior of titmice, tits and chickadees (Family Paridae) is especially well-studied. Further, exhibiting mobbing behavior and alarm calling at or in the nest can increase the fitness of incubating females and their young 21, 22. Although moving towards the predator while mobbing seems controversial in terms of immediate predation risk, it ultimately can hold the benefit of chasing the predator away 18, 19, 20. Additionally, calls can transmit information about a predator’s type 15, size 16 and distance 17. During mobbing, songbirds produce distinct mobbing calls, move towards the predator and display stereotype behaviors to recruit others and deter the predator 12, 13, 14. Usually, alarm calls are produced to inform others about a threat that causes them to flee or hide, mobbing calls on the other hand are intended to attract hetero- and conspecifics to join a mobbing flock 9, 10, 11. Many bird species produce alarm or mobbing calls after a predator has been detected 6, 7, 8. Animal vocalizations have been studied in a wide variety of taxa and some vocal signals in avian and mammalian species are even known to encode information about environmental factors such as the presence of predators and food 2, 3, 4, 5. Vocalizations in contrast can be transmitted over longer distances and are therefore suitable to transmit information also to individuals that are not in visual contact to the sender 1. Visual signals are normally visible over short distances due to their physical properties. This suggests that the basic D calls are varied depending on threat intensity.Īnimals transmit information in various ways with vocal, visual and olfactory signals being the most common ones. Furthermore, birds produced more D calls towards the high-threat predator. Great tits produced significantly longer D calls with more elements and longer intervals between elements when confronted with a sparrowhawk (high-threat) compared to a tawny owl (low-threat) mount. We found great tits to vary the number of D elements and the interval between those elements. ![]() We hypothesized, based on results of studies in other paridae species, that tits vary the number or type of elements of a call according to predatory context. We conducted a study with great tits ( Parus major) in the field where we presented taxidermy mounts of two predators of different threat levels (tawny owl, Strix aluco, and sparrowhawk, Accipiter nisus) and compared the mobbing calls of these two contexts. Species use the number of elements within a call, call frequency or call type to encode information. In birds, the vocalizations of the Family Paridae (titmice, tits and chickadees) are well-studied and have been shown to recruit conspecifics and encode information about predation risk. Many species are known to use vocalizations to recruit con- and heterospecifics to mobbing events. ![]()
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