Egg turning behavior and incubation temperature in Forster’s terns in relation to mercury contamination

Abstract

Egg turning behavior is an important determinant of egg hatchability, but it remains relatively understudied. Here, we examined egg turning rates and egg temperatures in Forster’s terns (Sterna forsteri). We used artificial eggs containing a data logger with a 3-D accelerometer, a magnetometer, and a temperature thermistor to monitor parental incubation behavior of 131 tern nests. Overall, adults turned their eggs an average (±SD) of 3.8 ± 0.8 turns h-1, which is nearly two times higher than that of other seabirds. Egg turning rates increased with nest initiation date. We also examined egg turning rates and egg temperatures in relation to egg mercury contamination. Mercury contamination has been shown to be associated with reduced egg hatchability, and we hypothesized that mercury may decrease egg hatchability via altered egg turning behavior by parents. Despite the high variability in egg turning rates among individuals, the rate of egg turning was not related to mercury concentrations in sibling eggs. These findings highlight the need for further study concerning the potential determinants of egg turning behavior.

Organochlorines, perfluoroalkyl substances, mercury, and egg incubation temperature in an Arctic seabird: Insights from data loggers

“…However, our results do not report any relationships between PFASs/Hg and T inc . This is supported by a recent investigation by Taylor et al (), who found no relationship between egg Hg contamination and T inc of Forster terns. Thus, our research contributes to filling the gap in knowledge, but additional studies are needed to confirm the generality of our findings in other bird species and, importantly, targeting the specific chemicals involved in avian T inc variations.…”

“…Using artificial egg loggers, we investigated whether the most contaminated kittiwakes were less committed in incubating their clutch and less able to provide appropriate egg warming. Embedded in artificial eggs, these loggers can provide almost continuous (every second) and precise recording of incubation behaviors (Shaffer et al ; Kelsey et al ; Clatterbuck et al ; Taylor et al ). Specifically, we examined the relationships between blood levels of 3 groups of contaminants (organochlorines, PFASs, and Hg) and T inc in a kittiwake population from Svalbard in the Norwegian Arctic.…”

Assessing nest attentiveness of Common Terns via video cameras and temperature loggers

“…It should be noted that the temperatures reported here are well below the known incubation ranges for terns (e.g. Taylor et al 2018), providing further evidence that iButtons would not be sufficient for measuring exact egg temperatures but provide a sufficient proxy for the purposes of our work.…”

“…The nest characteristics of COTE also proved to be a challenge, as the simple scrape nest structure allowed iButtons in unattended nests to be easily covered with windblown sand and invalidate subsequent data. Researchers should carefully consider their objectives and the use of other logger techniques (i.e., Arnold et al 2006;Taylor et al 2018) if windblown substrate is likely to present a challenge.…”

“…day vs night; Morris and Hunter 1976). Fortunately, recent work with techniques such as camera traps (Norwood 2011;Hart et al 2016), RFID loggers (Bonter and Bridge 2011; Riechert and Becker 2017), temperature loggers (Arnold et al 2006;Norwood 2011) and egg loggers (Shaffer et al 2014;Taylor et al 2018) appears to provide a promising means to resolve the dearth of high temporal resolution nest attentiveness data. For example, Arnold et al (2006) used temperature loggers to quantify the period of time COTE deserted their nests when evading owl predation pressure.…”