Discriminating uniparental and biparental breeding strategies by monitoring nest temperature

Abstract

Birds exhibit a wide diversity of breeding strategies. During incubation or chick-rearing, parental care can be either uniparental, by either the male or the female, or biparental. Understanding the selective pressures that drive these different strategies represents an exciting challenge for ecologists. In this context, assigning the type of parental care at the nest (e.g. biparental or uniparental incubation strategy) is often a prerequisite to answering questions in evolutionary ecology. The aim of this study was to produce a standardized method unequivocally to assign an incubation strategy to any Sanderling Calidris alba nest found in the field by monitoring nest temperature profiles. Using drops of >3°C in nest temperature (recorded with thermistors) to distinguish incubation and recess periods, we showed that the number of recesses and the total duration of these recesses from 09:00 to 17:00 h UTC allowed us reliably (99.1% after 24 h and 100% when monitoring the nest for at least 4 days) to assign the incubation strategy at the nest for 21 breeding adults (14 nests). Monitoring nest temperature for at least 24 h is an effective method to assign an incubation strategy without having to re-visit nests, thereby saving time in the field and minimizing both disturbance and related increase in predation risk of clutches. Given the advantages of our method, we suggest that it should be used more widely in studies that aim to document incubation strategies and patterns in regions where ambient temperatures are at least 3°C below the median nest temperature.

Accuracy of nest fate classification and predator identification from evidence at nests of Least Terns and Piping Plovers

“…, Hartman & Oring , Weidinger , Schneider & McWilliams , Moreau et al . ). However, the disadvantage of data loggers is that predators as well as predatory and nest defence behaviours cannot be determined.…”

Nest attentiveness drives nest predation in arctic sandpipers

“…At each site, we monitored the incubation behaviour of one to three species of sandpipers (seven species in total). Three species are uniparental (little stint Calidris minuta, Temminck's stint Calidris temminckii and white-rumped sandpiper Calidris fuscicollis), three species are biparental (dunlin Calidris alpina, Baird's sandpiper Calidris bairdii and semipalmated sandpiper Calidris pusilla), and one species, the sanderling Calidris alba, exhibits a mixed strategy with nests incubated by either two or only one adult in the same population (Reneerkens et al 2011, Moreau et al 2018. All species lay a typical clutch of four eggs (rarely three or five) in a shallow nest scrape directly on the tundra's surface (Reid et al 2002).…”

“…a period when eggs are not incubated) to start when the temperature dropped by ≥3 °C below the median incubation temperature of a nest (measured over 24 h periods) and to end when the temperature returned above this threshold (see Fig. 1 in Moreau et al 2018). Hence, all temperature profiles shorter than 24 h were excluded from the analyses.…”

Behavioural responses of breeding arctic sandpipers to ground-surface temperature and primary productivity

“…We also monitored four species with a biparental incubation strategy, including dunlin (Calidris alpina), Baird's sandpiper (Calidris bairdii), purple sandpiper (Calidris maritima) and semipalmated sandpiper (Calidris pusilla) ( Ashkenazie and Safriel, 1979;Gill and Tomkovich, 2004;Holmes, 1966;Pierce, 1997). Finally, we monitored one species with a mixed strategy, the sanderling (Calidris alba), where some nests are incubated by one parent (male or female) and others are incubated by both (Moreau et al, 2018;Reneerkens et al, 2014). Nests were found systematically by rope-dragging or opportunistically by walking through suitable breeding habitat, flushing incubating birds and/or following them visually as they walk back to their nest.…”

“…Male and female adults within pairs of Calidris species can either incubate nests cooperatively (henceforth referred to as "biparental species") or alone (henceforth referred to as "uniparental species"), and in a few species a mix of both strategies can be found within populations (see e.g. Bulla et al, 2017;Moreau et al, 2018;Reneerkens et al, 2011). Biparental incubation allows a quasi-continuous heat input into the eggs and gives both mates substantial time to forage (Bulla et al, 2014;Norton, 1972).…”