At–Sea Behavior Varies with Lunar Phase in a Nocturnal Pelagic Seabird, the Swallow-Tailed Gull

Abstract

Strong and predictable environmental variability can reward flexible behaviors among animals. We used long-term records of activity data that cover several lunar cycles to investigate whether behavior at-sea of swallow-tailed gulls Creagrus furcatus, a nocturnal pelagic seabird, varied with lunar phase in the Galápagos Islands. A Bayesian hierarchical model showed that nighttime at-sea activity of 37 breeding swallow-tailed gulls was clearly associated with changes in moon phase. Proportion of nighttime spent on water was highest during darker periods of the lunar cycle, coinciding with the cycle of the diel vertical migration (DVM) that brings prey to the sea surface at night. Our data show that at-sea behavior of a tropical seabird can vary with environmental changes, including lunar phase.

Endogenous Programs and Flexibility in Bird Migration

“…In addition, recent findings from the European Nightjar call attention to yet another temporal domain that may have been largely overlooked, at least in landbirds. Nocturnally migratory nightjars time fueling and migration events to the different phases of the moon (Norevik et al, 2019), and thereby call for further studies of moon cycle effects on migratory birds, ideally with a circannual perspective (Chapin and Wing, 1959;Cruz et al, 2013).…”

Seabirds During Arctic Polar Night: Underwater Observations from Svalbard Archipelago, Norway

“…Some seabird species have learned to use nocturnal light (moonlight and starlight) and frequently perform foraging dives at night (Regular et al 2011). For example, Swallow-tailed Gulls (Creagrus furcatus) maximize their foraging activity during darker periods of the lunar cycle (Cruz et al 2013) in response to the availability of their prey, which migrates toward deeper water during the day and to the surface at night (a phenomenon called diel vertical migrations; Zaret and Suffern 1976). Red-legged Kittiwakes (Rissa brevirostris) also concentrate their foraging during nighttime since their main prey, lanternfish (Myctophidae), are available at the surface during this period (Kokobun et al 2015).…”

Uncovering periodic patterns of space use in animal tracking data with periodograms, including a new algorithm for the Lomb-Scargle periodogram and improved randomization tests

“…Most fishing trips are towards nutrient-rich up-welling zones off the coast of Peru about 1200 km from the breeding island. Waved albatross’ diet include a large proportion of squids [ 42 ] which are mainly available to them at night [ 6 ]. Although waved albatrosses exhibit some morphological adaptations such as larger eyes and larger distance between them than related species, we suppose that they still have poor night vision like most other albatrosses [ 43 , 44 ].…”

“…Periodic behaviors nevertheless constitute manifestations of complex, finely-tuned suites of behaviors that have been shaped by natural patterns of spatiotemporal variation in resources and risk [ 3 , 4 ], so that their occurrence, or their absence, is often central to the ecology of species and individuals [ 5 ]. In particular, animals’ responses to lunar cycles [ 6 ] and resource depletion/recovery cycles [ 7 ] remain poorly described in most cases, and much insight could potentially be gained from analyzing animal movements with respect to those cycles. Memory effects, cognitive abilities [ 8 , 9 ], and social interactions [ 10 ] represent other intriguing pathways through which periodicities could emerge in animal movement.…”