Environmental factors predicting the orientation of sea turtle hatchlings on a naturally lighted beach: A baseline for light-management goals

Hirama, Shigetomo; Witherington, Blair E.; Kneifl, Kristen; Sylvia, Andrea; Wideroff, Morgan; Carthy, Raymond R.

doi:10.1016/j.jembe.2021.151568

Cited by 5 publications

(10 citation statements)

References 35 publications

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“…The attraction and disorientation of seabirds by artificial lights is a poorly understood phenomenon causing mass mortality events of seabirds (Rodríguez et al, 2017). Contrary to other marine animals stranded by light pollution, e.g., sea turtles that leave tracks on beach sand (Hirama et al, 2021), tracking the fledgling flights from their nests to grounding locations is challenging. Our experimental study has revealed that intrinsic factors, such as down abundance in the plumage, are associated with the probability of being grounded by artificial lights.…”

Section: Discussionmentioning

confidence: 99%

Tracking Flights to Investigate Seabird Mortality Induced by Artificial Lights

Rodríguez

Rodríguez²,

Acosta

et al. 2022

Front. Ecol. Evol.

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Light pollution causes attraction and/or disorientation of seabirds, leading to mortality events due to multiple threats. This is a poorly understood phenomenon, largely because of the challenge to track seabirds at night from their nests to the grounding light-polluted locations. New tracking technologies can inform about this phenomenon. Here, we used GPS transmitters with remote download to track the flights of Cory’s shearwater Calonectris borealis fledglings from an inland experimental releasing site to the ocean. We released birds assigned to three experimental groups: GPS tagged, tape-labelled, and control birds. We assessed how both intrinsic (such as body mass, body condition, body size, and down abundance) and extrinsic (i.e., flight descriptors, such as distance, straightness, and flight duration, wind speed, or moon luminance) factors influenced light-induced groundings by using two datasets: one including the three groups and another including just the GPS tagged birds (as GPS devices provide unique information). We tested whether the probability of being grounded by artificial lights was related to intrinsic factors. With the use of the whole dataset, we found that birds with a higher down abundance had a higher probability of being grounded. GPS data revealed that the probability of being grounded was positively related to the tortuosity of flights and the overflown light pollution levels. Also, birds with slower flights were more likely to be grounded than birds with fast flights. Tortuosity increased with light pollution levels but decreased with the ambient light of the moon. GPSs with remote data download provided information on birds reaching the ocean, this being a substantial improvement to previous studies requiring recapture of the individuals to retrieve the data. GPS tracks of birds reaching the ocean allowed us to know that some birds overflew coastal urban areas so light-polluted as the landing sites of grounded birds. We provide novel scientific-based information to manage seabird mortality induced by artificial lights.

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Section: Discussionmentioning

confidence: 99%

Tracking Flights to Investigate Seabird Mortality Induced by Artificial Lights

Rodríguez

Rodríguez²,

Acosta

et al. 2022

Front. Ecol. Evol.

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“…Loggerhead hatchlings crawled away from artificially created dark silhouettes in both laboratory and in situ experiments (Parker 1922;Salmon et al 1992;Tuxbury and Salmon 2005). These findings indicate that tactile senses, activated by gravity, as when a hatchling descends a slope, serve little importance to navigation, whereas that the dark silhouette from the dune is important for seaward orientation (Limpus and Kamrowski 2013;Hirama et al 2021).…”

Section: Introductionmentioning

confidence: 92%

“…We measured two parameters representing hatchling orientation: (1) angular range, which depicts the spread of hatchling tracks and thus indicates precision of orientation, and (2) modal divergence, which shows the difference between the predominant direction in which hatchlings crawled (hereafter, mode) and the direction as tangent line to the sea, used to quantify orientation accuracy. From a hatchling emergence point, we marked a 10-m-radius circle (hereafter, testing circle) and measured the bearing of three hatchling tracks, one for a mode direction and two for calculating an angular range, where they intercepted the testing circle (Hirama et al 2021). Kamrowski et al (2014) considered the midpoint of bearing within an angular range as a mode direction.…”

Section: Study Sites and Hatchling Orientation Parametersmentioning

confidence: 99%

“…Crawling along an indirect path wastes limited energy and risks exhaustion and dehydration (Lorne and Salmon 2007), as well as predation (Tomillo et al 2010). Hatchling orientation accuracy has also been shown to increase as the distance from nests to dune decreases, whereas the slope of the beach showed no correlation with orientation (Hirama et al 2021). Loggerhead hatchlings crawled away from artificially created dark silhouettes in both laboratory and in situ experiments (Parker 1922;Salmon et al 1992;Tuxbury and Salmon 2005).…”

Section: Introductionmentioning

confidence: 99%

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Accuracy and precision of sea-finding orientation as a function of dune proximity in hatchlings of two species of sea turtles

Hirama

Witherington²,

Hirsch³

et al. 2023

Mar. Freshw. Res.

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Context Sea turtle hatchlings generally emerge at night from nests on sand beaches and immediately orient using visual cues, which are believed to entail the difference in brightness between the light seen in the seaward direction and that seen in the duneward direction. Aim The aim of this study was to understand how dune proximity affected hatchling orientations in two sea turtle species that share a nesting beach 15 km long and 25.3 ± 9.4 m (N = 215) from dune to waterline, with low to moderate artificial light nearby. Methods For hatchling loggerhead and green turtles, we measured accuracy and precision of orientation, tested differences in distance from nest to dune, and investigated the effect of dune proximity on hatchling orientation. Key results We found a significant decrease in hatchling orientation accuracy and precision in both species as the distance increased from nests to dune. Loggerhead and green turtles showed similar orientation ability when in the same proximity to the dune. Conclusions We conclude that dune features provide important cues for hatchling orientation on sea turtle nesting beaches. Implications Restoring and maintaining natural beach profiles, especially dune systems, is likely to increase the accuracy and precision of sea finding in hatchling sea turtles.

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“…Lethal effects of ALAN on these species have long been documented: moths and other insects swarm open flames [ 7 , 8 ], migrating seabirds collide with lighthouses [ 9 , 10 ], deer freeze in headlights [ 11 , 12 ], and sea turtle hatchlings crawl into oncoming traffic [ 13 , 14 ]. In recent decades, as ALAN has gained legitimacy as a conservation threat [ 15 ], researchers have further documented sublethal effects on the foraging [ 16 , 17 ], courtship [ 18 , 19 ] and mate success [ 20 , 21 ] of diverse taxa, with cascading consequences for ecological communities [ 22 – 26 ].…”

Section: Introductionmentioning

confidence: 99%

Artificial light impacts the mate success of female fireflies

Owens

Lewis

2022

R. Soc. open sci.

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Anthropogenic light pollution is a novel environmental disruption that affects the movement, foraging and mating behaviour of nocturnal animals. Most of these effects are sublethal, and their net impact on reproductive fitness and population persistence is often extrapolated from behavioural data. Without dedicated tracking of wild individuals, however, it is impossible to predict whether populations in light-polluted habitats will decline or, instead, move to shaded refuges. To disentangle these conflicting possibilities, we investigated how artificial light affects mating and movement in North American Photinus , a genus of bioluminescent fireflies known to experience courtship failure under artificial light. The degree to which artificial light reduced mate success depended on the intensity of the light treatment, its environmental context, and the temporal niche of the species in question. In the laboratory, direct exposure to artificial light completely prevented mating in semi-nocturnal Photinus obscurellus . In the field, artificial light had little impact on the movement or mate success of local Photinus pyralis and Photinus marginellus but strongly influenced mate location in Photinus greeni ; all three species are relatively crepuscular. Our nuanced results suggest greater appreciation of behavioural diversity will help insect conservationists and dark sky advocates better target efforts to protect at-risk species.

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Environmental factors predicting the orientation of sea turtle hatchlings on a naturally lighted beach: A baseline for light-management goals

Cited by 5 publications

References 35 publications

Tracking Flights to Investigate Seabird Mortality Induced by Artificial Lights

Tracking Flights to Investigate Seabird Mortality Induced by Artificial Lights

Accuracy and precision of sea-finding orientation as a function of dune proximity in hatchlings of two species of sea turtles

Artificial light impacts the mate success of female fireflies

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