Radiotagged fledgling Savannah Sparrows <i>Passerculus sandwichensis</i> at risk of entanglement in vegetation

Vliet, Heidi E.J. van; Stutchbury, Bridget J. M.

doi:10.1111/ibi.12615

Cited by 3 publications

(9 citation statements)

References 21 publications

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“…It is possible that adverse effects of radiotags on survival may be species‐specific. For instance, fledglings of grassland nesting birds may be at greater risk for having their radiotags become entangled in vegetation when they are immobile and hide under thick vegetation upon fledging (van Vliet & Stutchbury ). Furthermore, Naef‐Daenzer and Grüebler () found no adverse effects of their radiotags on juvenile Barn Swallows in Europe which were 0.3 g heavier than the tags used in this study.…”

Section: Discussionmentioning

confidence: 99%

Individual condition, but not fledging phenology, carries over to affect post‐fledging survival in a Neotropical migratory songbird

Evans

Hobson

Kusack

et al. 2019

Ibis

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Migratory animals face severe time and energy constraints during their annual cycle. These constraints may be exacerbated in young animals by conditions experienced during development that can affect both phenotype and phenology. For young migratory songbirds, the period between fledging and autumn migration, the post‐fledging period, is believed to represent a time of intense selective pressure. However, there has yet to be a study that has assessed post‐fledging survival for the entirety of the post‐fledging period, probably due to the challenge of following juveniles as they move broadly across the landscape (tens to hundreds of kilometres). To overcome this challenge, we used an automated radiotelemetry array spanning 60 000 km2 in southern Ontario, Canada, and miniature digital radiotelemetry tags to track 216 juvenile Barn Swallows Hirundo rustica continuously from fledging to migration. We hypothesized that young that fledged in better condition and earlier in the breeding season would have higher survival relative to birds fledging in poorer condition, because they have more energy to deal with resource constraints, and that early‐fledging birds would depart on migration earlier than late‐fledging birds because there is probably a fixed period of time required post‐fledging to prepare for migration. We found that average cumulative apparent survival was 42% and that condition in the nest was a strong positive predictor of post‐fledging apparent survival. We also found that birds that fledged earlier in the season departed on migration earlier in the autumn relative to late‐fledging birds. Contrary to our prediction, average apparent survival was equal for early‐ and late‐fledging birds. Our results suggest that factors during development that promote better nestling condition are critical for predicting future apparent survival prior to migration. Differences in annual apparent survival between early‐ and late‐fledging songbirds, as commonly observed, may be driven by events occurring at later stages of the annual cycle.

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Section: Discussionmentioning

confidence: 99%

Individual condition, but not fledging phenology, carries over to affect post‐fledging survival in a Neotropical migratory songbird

Evans

Hobson

Kusack

et al. 2019

Ibis

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“…have shown only small and inconsistent effects of tags on diving behaviour in marine habitat (Evans et al 2020), this effect might be stronger in species such as Dipper, because the risk of entanglement among structures of riverbanks. As much as 23% of tags and antennas were found entangled with terrestrial vegetation in a study of the Savannah Sparrow Passerculus sandwichensis (Van Vliet & Stutchbury 2018). Although we have no direct evidence of the negative effect of transmitters in this study, we cannot exclude that in three cases, the fledglings with tags were entangled among roots under the riverbank and not found dead.…”

Section: Discussionmentioning

confidence: 99%

“…The published data on speed of natal dispersal in the Dipper fledglings are highly variable (Galbraith & Tyler 1982, Tyler & Ormerod 1994, Kunstmüller 2013, Hrčková & Baláž 2019, while dispersal from fledging to the time of independence has not been studied in detail to date. Our data, based on daily radio-tracking, show gradually increasing distance from the natal nest.…”

Section: Fledgling Fatementioning

confidence: 99%

“…Due to their ecology and the applicability of various field methods, Dippers (family Cinclidae) represent a suitable model for studying various parameters ranging from population dynamics (Tyler & Ormerod 1994, Loison et al 2010 to river ecology (Ormerod at al. 1991).…”

Section: Introductionmentioning

confidence: 99%

“…1991). The breeding biology of the White-throated Dipper Cinclus cinclus is known well (Cramp & Simmons 1988, Tyler & Ormerod 1994) but only a few studies have focused on survival and dispersal during the post-fledging period. Fuchs (1970) relied on direct observation of colour-banded individuals, Kunstmüller (2013) on retrapping of aluminium ringed individuals and Galbraith & Tyler (1982) on combination of ringing recoveries and field observations.…”

Section: Introductionmentioning

confidence: 99%

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Post-Fledging Survival and Dispersal of the White-Throated Dipper Cinclus cinclus

Bureš,

Baláž,

Slavkovská

et al. 2023

Acta Ornithologica

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The post-fledging period is still an understudied stage of avian life cycle, even in the case of otherwise frequently studied species. The general breeding biology of the White-throated Dipper is known well, but only a few studies have focused on survival and dispersal during the post-fledging period. In this study we report on results revealed by radio-telemetry, a method which has not been used in the species to date. Nestlings (37 individuals from 9 nests) in a mountain population of central Slovakia were radio-tagged on the mean expected fledging age (22 days post-hatch) and monitored daily until death, disappearance or reaching independence. Only 22–32% (depending on the handling of uncertain data) of fledglings survived the first 12 days post-fledging. Predation was the most frequently suspected cause of death. The daily survival rate was markedly lower during the first two days after fledging (0.717–0.758) than later (0.914–0.941). The daily movement distance remained stable during the first week post-fledging and increased around the age of reaching independence (c. 12 days post-fledging). On the other hand, the distance from the natal nest and the within-brood distance (length of river occupied by fledglings from the same nest) increased gradually since fledging. We propose that in our study population the low post-fledging survival could be potentially balanced by frequent renesting and/or double-brooding, timing of which corresponds well with the age of reaching independence when juvenile birds disperse outside the natal territory.

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Considerations for radio-transmitter specifications on songbirds: color and antenna length matter too

Jones,

Cooper,

Haradon

et al. 2024

JFO

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Researchers studying avian space use, dispersal, survival, and migration select tracking tags that optimize tag size (dimensions) and mass relative to the focal species to minimize risk to birds as they move and fly. Here we argue that antenna length and transmitter color are also critical tag design parameters that must be considered. Based on a review of the songbird tracking literature and unpublished cases, we found most cases of entanglement, which can result in bird injuries and death, occurred with longer antennas (>13 cm). However, such cases cannot infer rates of mortality or survival, nor may they be representative of entanglements across antenna lengths and studies using radio tags. Additionally, white or brightly colored transmitters that contrast with plumage, particularly of cryptically colored females and juveniles, may increase visibility to predators and result in higher mortality, or alternatively, cause a female to eject a nestling by mistaking the tag for a fecal sac or foreign object. Consequently, we call on researchers to report and publish cases of antenna entanglement, and for journal editors to encourage and applaud such reports, such that data can be compiled to inform guidelines on tag antenna lengths for different species. Future research is also needed to examine the impacts of tag color on parental behavior and survival of tagged birds. Meanwhile, researchers should strive to ensure that their tag color does not contrast markedly with avian plumages, while also taking care not to alter (i.e., do not color over) areas required for harness attachment, activating and deactivating tags. We hope such efforts will enable researchers and manufacturers to make more informed decisions about tracking tag design, particularly with respect to balancing the benefits of longer antennas, which provide greater power and detection distance, with risks of bird entanglement and mortality.RESUMEN. Los investigadores que estudian el uso del espacio por las aves, dispersión, supervivencia y migración, seleccionan dispositivos de seguimiento que optimizan el tamaño del dispositivo (dimensiones) y la masa respecto a la especie en cuestión para minimizar el riesgo para las aves mientras se mueven y vuelan. Aquí argumentamos que la longitud de la antena y el color del transmisor son también parámetros críticos del diseño de los dispositivos que deben tenerse en cuenta. En base a una revisión de la bibliografía sobre el seguimiento de pájaros cantores y casos no publicados, encontramos que la mayoría de los casos de entrelazamientos, los cuales pueden provocar lesiones y muerte de aves, ocurrieron con antenas largas (>13 cm). Sin embargo, estos casos no pueden inferir tasas de mortalidad o supervivencia, ni pueden ser representativos de entrelazamientos a través de distintas longitudes de antenas y estudios que utilizan radiotransmisores. Además, los radiotransmisores de colores blanco o brillantes que contrastan con el plumaje, particularmente de hembras y juveniles con colores crípticos, pueden aumentar la ...

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Radiotagged fledgling Savannah Sparrows Passerculus sandwichensis at risk of entanglement in vegetation

Cited by 3 publications

References 21 publications

Individual condition, but not fledging phenology, carries over to affect post‐fledging survival in a Neotropical migratory songbird

Individual condition, but not fledging phenology, carries over to affect post‐fledging survival in a Neotropical migratory songbird

Post-Fledging Survival and Dispersal of the White-Throated Dipper Cinclus cinclus

Considerations for radio-transmitter specifications on songbirds: color and antenna length matter too

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