Diversity of incubation rhythms in a facultatively uniparental shorebird – the Northern Lapwing

Abstract

In birds, incubation by both parents is a common form of care for eggs. Although the involvement of the two parents may vary dramatically between and within pairs, as well as over the course of the day and breeding season, detailed descriptions of this variation are rare, especially in species with variable male contributions to care. Here, we continuously video-monitored 113 nests of Northern Lapwings Vanellus vanellus to reveal the diversity of incubation rhythms and parental involvement, as well as their daily and seasonal variation. We found great between-nest variation in the overall nest attendance (68–94%; median = 87%) and in how much males attended their nests (0–37%; median = 13%). Notably, the less the males attended their nests, the lower was the overall nest attendance, even though females partially compensated for the males’ decrease. Also, despite seasonal environmental trends (e.g. increasing temperature), incubation rhythms changed little over the season and 27-day incubation period. However, as nights shortened with the progressing breeding season, the longest night incubation bout of females shortened too. Importantly, within the 24h-day, nest attendance was highest, incubation bouts longest, exchange gaps shortest and male involvement lowest during the night. Moreover, just after sunrise and before sunset males attended the nest the most. To conclude, we confirm substantial between nest differences in Lapwing male nest attendance, reveal how such differences relates to variation in incubation rhythms, and describe strong circadian incubation rhythms modulated by sunrise and sunset.

Daily Rhythms of Female Self-maintenance Correlate with Predation Risk and Male Nest Attendance in a Biparental Wader

“…One explanation might be that predators are scarce around noon, and females can thus perform other activities associated with conspicuous movement on the nest, such as preening, egg turning, improving the nest lining, and feeding, which it is useful to perform at the time of lower predator activity. Noon is also the time when incubation attendance drops (Sládeček et al, 2019c).…”

“…Since our analysis covered a single randomly selected day from the incubation period of each nest, we cannot exclude the possibility that females with an extremely low amount of sleep slept more during the previous days or would sleep more in the subsequent days. However, incubation patterns, such as incubation attendance and male contribution, remain almost consistent in the course of the incubation period and are highly repeatable in the Northern Lapwing (Sládeček et al, 2019c). In addition, the sleeping effort changed little over the incubation stage and season (Suppl.…”

“…We monitored the incubation on 55 nests of Northern Lapwing. Using small cameras placed approximately 1.5 m from the nest, we obtained continuous video recordings of 3 days (median, range: 1-5; Sládeček et al, 2019c). Since it takes an immense amount of time to extract the detailed behavior, we randomly chose a 1-day complete record for each nest (i.e., 24 h of uninterrupted recording).…”

“…Thus, the nests were not attended by either of the parents for 4.1 ± 2.3 h (mean ± SD, range: 0.8-14.7 h). For a detailed description of the Lapwing incubation pattern, see Sládeček et al (2019c).…”

“…In this study, we used continuous video recordings to investigate the behavioral rhythms of incubating Northern Lapwing ( Vanellus vanellus ) females. The Northern Lapwing is a biparentally incubating, ground-nesting wader with a variable contribution of males to incubation and almost exclusive female incubation at night (Sládeček et al, 2019c). Consequently, some females sit on the nest for only 50% of the time, while other females almost 90%.…”