Parental incubation exchange in a territorial bird species involves sex-specific signalling

Abstract

BackgroundEffective communication between sexual partners is essential for successful reproduction. Avian parents with biparental incubation need to know how to negotiate, when and who will incubate, and how to harmonize partner exchange at the nest. Although considerable effort has been dedicated to studies of incubation rhythms, few studies have investigated how behavioural signals serve to tighten cooperation between parents. Moreover, existing studies are almost exclusively restricted to species in which long distances between incubating and non-incubating parents prevent continuous communication during incubation. Thus, the most frequently described parental exchange system is a simple model characterized by the return of the non-incubating parent to the nest itself. Here, we propose more complex parental exchange behaviour in the Northern Lapwing (Vanellus vanellus), a territorial species capable of continuous partner communication during incubation and with a highly variable male contribution to incubation.ResultsNorthern Lapwing females regularly vocalized shortly before departing from the nest, while males mostly left the nest quietly. Responsiveness of the male to female vocalization, perhaps in combination with her flying away from the nest, helped to synchronize incubation care by increasing the probability of exchange, and also by shortening the exchange gaps. In contrast, a male-to-female exchange gap most often occurred after the male quietly flew away from the nest. The frequency of female vocal signalling was not correlated with the male incubation effort on a between-nest scale, but the highest probability of a female-to-male exchange occurred after vocal signalling by females with the most nest-attentive males. Conversely, lowered effort by females to vocalize in the night was accompanied by lower willingness of males to incubate.ConclusionsOur results suggest that (1) that the incubating parent can communicate with the non-incubating partner using sex-specific behavioural signals, and this helps to synchronize parental exchange on the nest, (2) this signalling may combine acoustic and visual cues, and (3) the efficiency of this signalling might influence the overall nest attendance. The presumption that the repertoire of behavioural signals during reproduction will be much more complex in territorial species that are capable of continuous communication between the partners during the incubation period should be further tested.Electronic supplementary materialThe online version of this article (10.1186/s12983-019-0306-0) contains supplementary material, which is available to authorized users.

Nest relief in the cryptically-incubating semipalmated sandpiper is quick, but vocal

“…In northern lapwings ( Vanellus vanellus ), exchange gaps were shorter when males relieved their calling female than when they relieved a non-calling female, and whenever a calling female left the nest for an incubation recess (i.e. no nest relief took place), her incubation recess was longer than when she left for the recess silently (Sládeček et al 2019). In zebra finches ( Taeniopygia guttata ), the calling rate of a returning male predicted the subsequent off-nest time of its female partner (Boucaud et al 2016a), while calling of an incubating female from inside the nest predicted whether or not the male relieved her from the nest (Boucaud et al 2017).…”

“…Whereas instantaneous coordination of incubation duties is possible in species where the off-duty parent (i.e. the one taking an incubation recess) stays near the nest (Smith et al 1978; Hawkins 1986; Glutz von Blotzheim 1999; Rodewald 2015; Sládeček et al 2019), such coordination is challenging in species where the off-duty parent forages or rests out of calling distance of the nest (Bulla et al 2015b). In some species, this can be hundreds or even thousands of kilometers away (Weimerskirch et al 1993; Weimerskirch 1995; González-Solís et al 2000; Boersma and Rebstock 2009).…”

Who takes care of the kids at when? Sex differences in avian parental care

“…Studies in birds have identified several factors that affect the (relative) contributions of the male and female parents in the ecological time scale, including the harshness of abiotic environments, especially temperature and rainfall [48][49][50][51], predation risk [52,53], the vulnerability of offspring in the absence of parental care [54,55], and the body condition of the parents themselves [56]. Studies also found that males and female can communicate and negotiate their parental effort [57][58][59][60][61], and the negotiation rules can be sex-specific [62]. Would those factors also play a role in driving sex roles evolution in different care forms in the evolutionary time scale?…”

What’s in a Moment: What Can Be Learned About Pair Bonding From Studying Moment-To-Moment Behavioral Synchrony Between Partners?

“…Prior to departing from the nest, females, but not males, perform vocal displays which appear to signal the male. Female vocalizing increases the likelihood that the male will incubate and decreases the duration of the exchange gap ( Sládeček et al, 2019 ). Despite significant species differences in how incubation duties are shared, the range of ways birds coordinate activities using dynamic vocal exchanges at the nest remains striking.…”