Size and accumulation of fuel reserves at stopover predict nocturnal restlessness in a migratory bird

Early arrival at the breeding site positively affects the breeding success of migratory birds. During migration, birds spend most of their time at stopovers. Therefore, determining which factors shape stopover duration is essential to our understanding of avian migration. Because the main purpose of stopover is to accumulate fat as fuel for the next flight bout, fuel reserves at arrival and the accumulation of fuel are both expected to affect stopover departure decisions. Here, we determined whether fuel reserves and fuel accumulation predict a bird's motivation to depart, as quantified by nocturnal migratory restlessness (Zugunruhe), using northern wheatears ( Oenanthe oenanthe ) that were captured and temporarily contained at spring stopover. We found that fuel reserves at capture were positively correlated with Zugunruhe, and negatively correlated with fuel accumulation. This indicates that fat birds were motivated to depart, whereas lean birds were set on staying and accumulating fuel. Moreover, the change in fuel reserves was positively correlated with the concurrent change in Zugunruhe, providing the first empirical evidence for a direct link between fuel accumulation and Zugunruhe during stopover. Our study indicates that, together with innate rhythms and weather, the size and accumulation of fuel reserves shape stopover duration, and hence overall migration time.

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The amount of available food affects diurnal locomotor activity in migratory songbirds during stopover

Scientific Reports ◽

10.1038/s41598-019-55404-3 ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 4

Author(s):

Andrea Ferretti ◽

Ivan Maggini ◽

Sara Lupi ◽

Massimiliano Cardinale ◽

Leonida Fusani

Keyword(s):

Locomotor Activity ◽

Food Availability ◽

Migratory Birds ◽

Migratory Restlessness ◽

Locomotory Activity ◽

Central Mediterranean ◽

Stopover Site ◽

Stopover Sites ◽

Migrating Birds ◽

Spring Stopover

AbstractMigratory passerine birds fly long distances twice a year alternating nocturnal flights with stopovers to rest and replenish energy stores. The duration of each stopover depends on several factors including internal clocks, meteorological conditions, and environmental factors such as availability of food. Foraging entails energetic costs, and if birds need to refuel efficiently, they should modulate their activity in relation to food availability. We investigated how food availability influences locomotor activity in migrating birds of six passerine species at a spring stopover site in the central Mediterranean Sea. We selected birds with low fat scores which we expected to be strongly motivated to refuel. We simulated stopover sites of different quality by providing temporarily caged birds with different amounts of food to simulate scarce to abundant food. We analysed the diurnal locomotory activity as a proxy for food searching effort. Low food availability resulted in an increased diurnal locomotor activity in almost all species, while all birds showed low intensity of nocturnal migratory restlessness. In conclusion, our study shows that food availability in an important determinant of behaviour of migratory birds at stopover sites.

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Rapid recovery by fat- and muscle-depleted Blackpoll Warblers following trans-oceanic migration is driven by time-minimization

The Auk ◽

10.1093/ornithology/ukab055 ◽

2021 ◽

Author(s):

Nicholas J Bayly ◽

Kenneth V Rosenberg ◽

D Ryan Norris ◽

Philip D Taylor ◽

Keith A Hobson

Keyword(s):

Negative Correlation ◽

Flight Muscle ◽

Migratory Birds ◽

Long Distance ◽

Stopover Duration ◽

Early Arrival ◽

Show Evidence ◽

Time Minimization ◽

Flight Muscles ◽

Initial Recovery

Abstract Nonstop endurance flights are a defining characteristic of many long-distance migratory birds, but subsequent recovery phases are not typically distinguished from fueling phases (collectively “stopovers”), despite endurance flights inducing marked physiological changes including flight muscle atrophy and gastrointestinal tract reductions. Here, we hypothesize that recovery requires unique behavioral adaptations, leading to departures from the predictions of optimal migration theory for time-minimizing migrants. We predict that recovering birds will (1) select (moist) food-rich habitats on arrival; (2) have slow initial fueling rates due to decreased gastrointestinal capacity; (3) show a negative correlation between stopover duration and arrival condition instead of a negative correlation with fuel deposition rate (FDR); (4) stopover longer than required to store energy reserves for subsequent flights; and (5) show evidence of rebuilding flight muscles. To test these predictions, we studied Blackpoll Warblers (Setophaga striata) in northern Colombia following trans-oceanic flights >2,250 km. Birds selected dry seasonal habitats, despite the proximity of moist forests, and among 1,227 captured individuals, 14–21% were emaciated and 88% had atrophied flight muscles. We recaptured 74 individuals, revealing net positive mass gains and, contrary to prediction (2), no evidence for slow initial recovery rates. Contrary to prediction (3), stopover duration was only weakly correlated with arrival condition and birds with high FDR (4.9% lean body mass day–1) had shorter durations (3 days) relative to birds with slower rates (7 days): both groups accumulated sufficient fuel to reach nonbreeding (over-wintering) grounds 500–1,000 km away. Mass increases were largely attributable to fat deposition but some birds improved flight muscle condition (31.9%), consistent with prediction (5). Together these results reveal a strong selection for time-minimization in the decisions made by Blackpoll Warblers following trans-oceanic flights, likely mediated through advantages to early arrival on nonbreeding grounds, contrary to our hypothesis of recovery imposing unique selection pressures.

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Migratory restlessness and stopover duration in Wood sandpiper Tringa glareola

Ethology Ecology & Evolution ◽

10.1080/03949370.2021.1878282 ◽

2021 ◽

pp. 1-17

Author(s):

Lorenzo Vanni ◽

Giulia Cerritelli ◽

Alessandro Turchi ◽

Dimitri Giunchi

Keyword(s):

Migratory Restlessness ◽

Stopover Duration

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Low reproductive success of the endangered Iberá Seedeater in its only known breeding site, the Iberá Wetlands, Argentina

The Condor ◽

10.1093/ornithapp/duab008 ◽

2021 ◽

Author(s):

Melanie Browne ◽

Sheela P Turbek ◽

Constanza Pasian ◽

Adrián S Di Giacomo

Keyword(s):

Breeding Season ◽

Migratory Birds ◽

Nest Survival ◽

Breeding Site ◽

Grassland Management ◽

Nest Site Selection ◽

Breeding Biology ◽

Cumulative Probability ◽

Conservation Area ◽

Northeastern Argentina

Abstract Subtropical grasslands are highly susceptible to habitat conversion and number among South America’s most threatened ecosystems. The grasslands of northeastern Argentina have been identified as a priority conservation area for threatened capuchino seedeaters because they constitute the main breeding area of these migratory birds. The Iberá Seedeater (Sporophila iberaensis) is a newly described species in the Iberá Wetlands in Argentina whose biology is still poorly understood. The endangered species inhabits grasslands but has only been reported to breed in the Iberá Wetlands ecoregion of northeastern Argentina. To explore the species’ association with grassland vegetation, we studied the breeding biology (clutch size, hatching success, and fledgling production) of the Iberá Seedeater and the main parameters that influence nest survival and nest-site selection. We conducted nest searches and banded adults and nestlings in Iberá National Park during the breeding seasons of 2016–2018. The breeding season of the Iberá Seedeater was highly synchronous and the cumulative probability of nest survival was 0.16. The daily nest survival rate decreased as the breeding season advanced, survival was lower for nests supported by Rhynchospora corymbosa than Paspalum durifolium, the two main nest substrates, and the main causes of nest failure were nest predation and strong winds. Additionally, the population exhibited male-biased site fidelity and a low female return rate. In contrast to other capuchinos, whose breeding biology is associated with upland grasslands, the Iberá Seedeater nested exclusively in flooded lowland grasslands on marsh plants. Thus, effective lowland grassland management is key to maintain the vegetation structure required for reproduction in the Iberá Seedeater.

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Using Bioacoustics to Examine Vocal Phenology of Neotropical Migratory Birds on a Wild and Scenic River in Arizona

Birds ◽

10.3390/birds2030019 ◽

2021 ◽

Vol 2 (3) ◽

pp. 261-274

Author(s):

Heather L. Bateman ◽

Sidney B. Riddle ◽

Erin S. Cubley

Keyword(s):

Sonoran Desert ◽

Migratory Birds ◽

Riparian Forest ◽

Bird Species ◽

Migratory Bird ◽

Bird Diversity ◽

Yellow Warbler ◽

Habitat Features ◽

The Usa ◽

Vocal Activity

Passive acoustic recorders have been used successfully as automated survey tools to detect terrestrial wildlife. However, few studies have monitored Neotropical migratory bird use of riparian forest habitat using this technology. Within dryland ecosystems, the forests along rivers support high bird diversity. Many bird species of conservation concern require these floodplain forest habitats for foraging, migration stop-overs, and breeding. Few studies have explored the use of acoustic records in riverine systems designated for conservation for their natural resource value via the Wild and Scenic Rivers Act in the USA. Using acoustic recorders, we document vocal activity of four riparian-obligate species (Bell’s Vireo, Vireo bellii; Summer Tanager, Piranga rubra; Yellow Warbler, Setophaga petechial; and Yellow-billed Cuckoo, Coccyzus americanus) to determine species occurrence along a Wild and Scenic River. We established three study reaches along the perennial Lower Verde River, in the Sonoran Desert of central Arizona, USA. Nine acoustic recorders were used over the period of 80–120 days during the summer of 2018. We measured vegetation composition and structure in 100 m2 plots paired with acoustic recorders. Visualizing vocal activity showed that three species were calling and singing at each reach; whereas, one species, the cuckoo, had fewer recordings and occurred later in the summer. We demonstrate the utility of acoustic monitoring even when applied to rare birds in complex riparian habitats. This information is important for land management and conservation efforts concerning these species of interest and identifying important habitat features in Southwestern US riparian woodlands.

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Hunting of migratory birds in North Sinai, Egypt

Bird Conservation International ◽

10.1017/s0959270915000180 ◽

2015 ◽

Vol 26 (1) ◽

pp. 39-51 ◽

Cited By ~ 8

Author(s):

PERRI EASON ◽

BASEM RABIA ◽

OMAR ATTUM

Keyword(s):

Migratory Birds ◽

Bird Species ◽

Migratory Bird ◽

Mediterranean Coast ◽

Population Declines ◽

Mp3 Players ◽

Southern Mediterranean ◽

Sand Bar ◽

North Sinai ◽

Desert Scrub

SummaryDuring autumn migration, people set trammel nets along most of the Mediterranean coast of Egypt, with migrating Common Quail Coturnix coturnix as their primary target. These nets capture large numbers of quail, but also illegally capture other birds, which are then killed. We present the results of surveys from 2008 to 2012 along these lines of nets on the coast of North Sinai, Egypt. In desert scrub, which covers most of the Sinai coast, the mean number of quail killed reached a high of 357.1 per km per day in 2012, with a grand mean over the study period of 191.9 per km per day. Trammel nets also captured 54 other bird species in 28 families. Species captured at the highest rates in desert scrub included Corncrake Crex crex, Isabelline Wheatear Oenanthe isabellina and Greater Short-toed Lark Calandrella brachydactyla. Based on mean rates of capture from 2008 to 2012 in desert scrub and sand bar habitats, we estimate 2.0 million quail and 0.5 million birds of other species are killed annually in North Sinai during the 45 days of peak migration. In 2012, however, after the use of MP3 players to attract quail became widespread, we estimate that 3.3 million quail and 0.5 million other birds were captured. Hunters near the coast have recently begun covering shrubs and trees with mist nets to catch passerines. From 2010 to 2012, mist nets along our survey routes caught birds of 17 species in three families, with seven of these species caught only in this type of net. Hunting is likely to be a contributing factor to population declines for some species that migrate across Egypt and further studies of migratory bird hunting along the southern Mediterranean shore are badly needed.

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Rainfall-induced changes in food availability modify the spring departure programme of a migratory bird

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2011.0332 ◽

2011 ◽

Vol 278 (1723) ◽

pp. 3437-3443 ◽

Cited By ~ 125

Author(s):

Colin E. Studds ◽

Peter P. Marra

Keyword(s):

Migratory Birds ◽

Marked Change ◽

Migratory Bird ◽

Breeding Period ◽

Climatic Warming ◽

Adaptive Responses ◽

American Redstarts ◽

Breeding Grounds ◽

Selection For ◽

Induced Changes

Climatic warming has intensified selection for earlier reproduction in many organisms, but potential constraints imposed by climate change outside the breeding period have received little attention. Migratory birds provide an ideal model for exploring such constraints because they face warming temperatures on temperate breeding grounds and declining rainfall on many tropical non-breeding areas. Here, we use longitudinal data on spring departure dates of American redstarts ( Setophaga ruticilla ) to show that annual variation in tropical rainfall and food resources are associated with marked change in the timing of spring departure of the same individuals among years. This finding challenges the idea that photoperiod alone regulates the onset of migration, providing evidence that intensifying drought in the tropical winter could hinder adaptive responses to climatic warming in the temperate zone.

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Does wind speed and direction influence timing and route of a trans-hemispheric migratory songbird (purple martin) at a migration barrier?

Animal Migration ◽

10.1515/ami-2018-0005 ◽

2018 ◽

Vol 5 (1) ◽

pp. 49-58 ◽

Cited By ~ 1

Author(s):

S. A. Abdulle ◽

K. C. Fraser

Keyword(s):

Wind Speed ◽

Migratory Birds ◽

Gulf Coast ◽

Yucatan Peninsula ◽

Yucatán Peninsula ◽

Shortest Distance ◽

Departure Date ◽

Purple Martin ◽

Migratory Songbird ◽

Departure Decisions

Abstract The influence of weather on the departure decisions and routes of migratory birds can now be further investigated with the use of direct tracking methods. We tested hypotheses for migration departure decisions and flight trajectories by determining the influence of wind speed and direction at the Yucatan peninsula in spring on departure date, migratory route, and longitude of arrival at the northern Gulf coast of a trans-hemispheric migratory songbird, purple martin (Progne subis). Birds were equipped with geolocators at their breeding colony and 36 were recaptured upon return after spring migration. While southerly tailwinds with low wind speeds prevailed at the Yucatan during the period of passage, we found that daily wind speed and direction were still important predictors of departure date. However, wind conditions at departure did not predict longitude of arrival at the US gulf coast after crossing the gulf. Birds appeared to favour the shortest distance across the Gulf of Mexico, aided by consistent tailwinds, but may have corrected for wind drift so as to land at a longitude near 88°, reflecting the shortest distance across from the Yucatan staging areas. Considering their use prior to departure, high quality roost sites at the Yucatan peninsula would be important conservation targets for this declining aerial insectivore.

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