Mixed effects of geolocators on reproduction and survival of Cerulean Warblers, a canopy-dwelling, long-distance migrant

Raybuck, Douglas W.; Larkin, Jeffrey L.; Stoleson, Scott H.; Boves, Than J.

doi:10.1650/condor-16-180.1

Cited by 18 publications

(17 citation statements)

References 25 publications

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“…This conclusion is supported by results obtained on two species of swallows by Fairhurst et al (2015), who observed that, despite the clear negative effect of geolocators on return rate, returning individuals had similar stress levels (as measured by corticosterone levels in feathers) compared to control ones. Similar observations come from other studies on species where surviving geolocator birds seemed not to differ in migration or breeding performance compared to control birds (Rodriguez et al 2009, Peterson et al 2015, Matyjasiak et al 2016, van Wick et al 2016, Bell et al 2017, although geolocator birds suffered higher inter-annual mortality (Raybuck et al 2017). In a meta-analysis of the effect of geolocators on shorebirds, the simple presence of the device was the most significant factor affecting return rates and hatching success (Weiser et al 2016).…”

Section: Discussionsupporting

confidence: 69%

“…However, barn swallows equipped with geolocators seemed to have the same flight performance as control individuals (Matyjasiak et al 2016). Small passerines equipped with geolocators may also perform similar to controls during breeding, but suffer increased inter-annual mortality (Raybuck et al 2017). Overall, it seems established that smaller species and aerial foragers suffer the most from carrying geolocators (Fairhurst et al 2015; but see Matyjasiak et al 2016 for lack of short-term effects on flight performance).…”

Section: Introductionmentioning

confidence: 97%

“…Since these devices can be miniaturized, they are currently widely used to track the annual migrations of even small-sized birds, including highly aerial species, like swifts (Stuchbury et al 2009, Åkesson et al 2012, 2016, Bairlein et al 2012, Bridge et al 2013, Kristensen et al 2013, Wellbrock et al 2017), but their impact on survival and flight performance remains to be fully explored (cf. Costantini and Møller 2013, Fairhurst et al 2015, Matyjasiak et al 2016, Raybuck et al 2017. Indeed, deployment of tracking devices such as geolocators on birds may entail negative effects, including, for instance, increased drag when the device is attached on the back of the bird, which may result in higher cost of transportation (Bowlin et al 2010, Pennycuick et al 2012.…”

Section: Introductionmentioning

confidence: 99%

“…Generally, studies aiming at assessing the potential detrimental effects of geolocators have used inter-annual return rate as a proxy of survival (Arlt et al 2013, Scandolara et al 2014, Blackburn et al 2016, Raybuck et al 2017. However, return rate may not correctly represent true survival whenever inter-annual recapture probability is much lower than 100% (Cooch and White 2017), for instance in species with low breeding site fidelity or when capture and manipulation at the nest promote colony desertion in the following year, as it may be the case for swift species, and for species that need to be recaptured to assess whether they have returned or not.…”

Section: Introductionmentioning

confidence: 99%

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Effect of light‐level geolocators on apparent survival of two highly aerial swift species

Morganti

Rubolini

Åkesson

et al. 2017

Journal of Avian Biology

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Light-level geolocators are currently widely used to track the migration of smallsized birds, but their potentially detrimental effects on survival of highly aerial species have been poorly investigated so far. We recorded capture-recapture histories of 283 common swifts Apus apus and 107 pallid swifts Apus pallidus breeding in 14 colonies in Italy, Spain, Sweden and Switzerland that were equipped with 10 different types of geolocators ('geolocator birds'), and compared their survival with that of, respectively, 215 common and 101 pallid swifts not equipped with geolocators ('control birds'). Data were analysed using both GLMMs with return rate as a proxy for survival and mark-recapture models to estimate survival while accounting for recapture probability. In all the analyses, geolocator birds showed reduced apparent survival compared to controls. Geolocator weight was always lower than 3% of body mass, and did not affect survival per se. Geolocators with a light-stalk, which is used in some geolocator models to reduce light sensor shading by feathers, decreased apparent survival more than models without light-stalk. Apparent survival of geolocator birds significantly varied among sites, being much higher in northern Europe. Despite in our analyses we could only partly account for variable recapture probabilities among sites and for inter-annual variability in survival, our results generally showed that equipping swifts with geolocators decreased their survival prospects, but also that the magnitude of this effect may depend on species-specific traits. These conclusions are in line with those of other studies on aerial foragers. We suggest that future studies tracking the movements of aerial insectivorous birds should use devices designed to minimize drag.

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Section: Discussionsupporting

confidence: 69%

Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effect of light‐level geolocators on apparent survival of two highly aerial swift species

Morganti

Rubolini

Åkesson

et al. 2017

Journal of Avian Biology

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“…We recovered only a small proportion of geolocators primarily due to low return rates. Impacts of geolocators on return rates have been documented for some species (Thaxter et al 2016, Raybuck et al 2017, but other studies have found no or mixed effects and more study is needed (López-López 2016, van Wijk et al 2016. In BC, 2 of 14 birds given geolocators returned, but the reduction in males on the study site (16 to 10) from year 1 to year 2 corresponded closely to the 7 males that received geolocators that did not return.…”

Section: Bobolink Returns and Geolocator Retentionmentioning

confidence: 92%

Migration tactics of a long-distance migratory songbird from across a continental breeding range

Renfrew¹,

Kim

Perlut

et al. 2019

The Wilson Journal of Ornithology

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Migration strategies in the avian world are often compared at the species level and evaluated relative to general ecology and constraints such as molting and breeding timetables. The advancement of tracking technology provides an opportunity to explore variation in more specific migration tactics within species and their populations as it relates to demographic and environmental factors throughout the annual cycle. We compare migration timing among 4 populations of Bobolink (Dolichonyx oryzivorus) from across the breeding range using data from light-level geolocators. The date of departure from the breeding grounds and the duration of southbound migration differed among breeding populations, and were more variable for eastern breeding populations compared to western populations farther from the main migration corridor. Despite variation in both timing and distance from the corridor among breeding populations, date of arrival at the major southbound stop in the Llanos of South America remained synchronous, but less so than previously described. Weekly flight distances were highly variable and did not differ among populations. Duration of northbound migration did not differ among populations and was half as long as the southbound migration. Our findings show Bobolink populations breeding near the species' relatively narrow migration corridor in the southeastern United States were more variable in terms of how they reached the first lengthy stop in the Llanos, suggesting more flexibility in migration tactics. Breeding locations were not associated, however, with the timing or duration of the remainder of their migratory schedule. Our findings support the hypothesis that food resources, both historical and present, drive and also modify the endogenous migration schedule of this flocking species with a split migration.

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Light stalks increase the precision and accuracy of non-breeding locations calculated from geolocator tags: a field test from a long-distance migrant

Blackburn

Burgess

Freeman³

et al. 2019

Bird Study

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Capsule: There is a substantial gain in precision and accuracy of geolocator locations when using a light stalk. Aims: Light stalks or tubes increase the accuracy of geolocators when tracking migrant birds because they reduce potential shading of the light sensor by feathers but may increase detrimental tag effects. We aimed to determine how adding light stalks to geolocator tags increased accuracy and precision of locations. Methods: We quantified how precision and accuracy of geolocator locations was affected by comparing variation of sunrise and sunset times from tags with variable length light stalks (6 of 0 mm, 8 of 5 mm and 21 of 10 mm). Tags were fitted to Whinchats Saxicola rubetra in central Nigeria (the known location to compare accuracy), and variance in latitude and longitude of geolocator estimated locations were also compared across light stalk lengths during spring migration stationary locations, and at breeding sites in Eastern Europe, for both Geolight and FlightR methods. Results: Without a light stalk, the standard deviation of sunset and sunrise times increased by 50% and 100% respectively (i.e. less precise): confidence intervals for latitude were larger by about 4.3 degrees at non-breeding low latitudes and 1.8 degrees at stopover latitudes, or confidence intervals for longitude were larger by 2.3 degrees, dependent on analysis method. Estimated sun elevation angles were significantly less accurate and so calculated non-breeding locations were significantly less accurate by about 8 degrees of latitude. Precision in sunrise, sunset times, latitude and longitude, was similar when using a 5mm or 10mm stalk. Conclusions: The results show a substantial gain in precision and accuracy of low latitude geolocator locations when using a light stalk that brings the sensor above covering feathers. There is no advantage from longer light stalk lengths than those necessary to just expose the light sensor above the feathers, at least for small passerines.

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Mixed effects of geolocators on reproduction and survival of Cerulean Warblers, a canopy-dwelling, long-distance migrant

Cited by 18 publications

References 25 publications

Effect of light‐level geolocators on apparent survival of two highly aerial swift species

Effect of light‐level geolocators on apparent survival of two highly aerial swift species

Migration tactics of a long-distance migratory songbird from across a continental breeding range

Light stalks increase the precision and accuracy of non-breeding locations calculated from geolocator tags: a field test from a long-distance migrant

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