Spring migration of Ruffs Philomachus pugnax in Fryslân: estimates of staging duration using resighting data

Seasonal bird migration involves long flights, but most time is actually spent at intermediate staging areas. The duration of stay at these sites can be evaluated with mark–recapture methods that employ day-to-day local encounters of individually marked birds. Estimates of staging duration are based on two probabilities: the immigration probability, the complement of a bird’s seniority to an area, and the emigration probability, the complement of the staying probability. Estimating total staging duration from seniority and staying probabilities requires validation for resighting data and here we compare three data categories of Ruffs Philomachus pugnax passing through The Netherlands during northward migration: (1) newly colour-ringed, (2) previously colour-ringed and (3) radio-tagged Ruffs (recorded by automated receiving stations). Between 2004 and 2008, 4363 resighting histories and 95 telemetry recording histories were collected. As sample sizes for females were low, only data for males were analysed. Possible catching effects affecting estimates of staging duration were explored. Staying probability was estimated for all data. Seniority however, could not be estimated for newly marked Ruffs; the assumption of equal ‘capture’ probability for reverse-time models applied to estimate seniority is violated for seasonal resighting histories starting with a catching event. Therefore, estimates of total staging duration were based on resightings of previously colour-marked birds only. For radio-tagged birds a minimal staging duration (time between tagging and last recording) was calculated. Modelling indicated that newly colour-ringed birds had a higher staying probability than previously colour-ringed birds, but the difference translated to a prolonged staging duration in newly ringed birds of only 0.4–0.5 d, suggesting a very small catching effect. The minimal staging duration of radio-tagged birds validated estimates of staging duration for colour-ringed birds in 2007 but not in 2005. In 2005 a low resighting probability resulted in underestimates of staging duration. We conclude that (1) estimates of staying probability can be affected by catching although effects on staging duration might be small, and that (2) low resighting probabilities can lead to underestimates in staging duration. In our study previously ringed Ruffs resighted in 2006–08 yielded reliable estimates of staging duration as data had sufficiently high resighting probabilities. Average staging durations varied between 19 d in 2008 and 23 d in 2006.

Impact of traffic management on black carbon emissions: a microsimulation study

This paper investigates the effectiveness of traffic management tools, includ- ing traffic signal control and en-route navigation provided by variable message signs (VMS), in reducing traffic congestion and associated emissions of CO2, NOx, and black carbon. The latter is among the most significant contributors of climate change, and is associated with many serious health problems. This study combines traffic microsimulation (S-Paramics) with emission modeling (AIRE) to simulate and predict the impacts of different traffic management measures on a number traffic and environmental Key Performance Indicators (KPIs) assessed at different spatial levels. Simulation results for a real road network located in West Glasgow suggest that these traffic management tools can bring a reduction in travel delay and BC emission respectively by up to 6 % and 3 % network wide. The improvement at local levels such as junctions or corridors can be more significant. However, our results also show that the potential benefits of such interventions are strongly dependent on a number of factors, including dynamic demand profile, VMS compliance rate, and fleet composition. Extensive discussion based on the simulation results as well as managerial insights are provided to support traffic network operation and control with environmental goals. The study described by this paper was conducted under the support of the FP7-funded CARBOTRAF project

Roost availability may constrain shorebird distribution:Exploring the energetic costs of roosting and disturbance around a tropical bay

High tides force shorebirds from their intertidal feeding areas to refuges known as roosts. This paper explores the energetic costs of roost disturbance of great knot (Calidris tenuirostris) and red knot (C. canutus) at Roebuck Bay, North-western Australia, assessing disturbance levels at different roost sites through direct observation and automatic radio-telemetry, and applying physiological equations and predictive roost choice models to estimate energetic costs of disturbance through a complete tidal cycle. The study area had a variety of roosts, but use of each was constrained by conditions of tide and time. The roost most suitable for shorebirds on daytime high tides of intermediate height experienced high levels of disturbance from both natural sources (birds of prey) and humans. Flight costs caused by disturbance at this site exceeded the costs of flying to and roosting at the nearest alternative roost, 25 km away. However, shorebirds did not roost at the alternate site, possibly because of the risk of heat stress in a prolonged flight in tropical conditions. Increases in disturbance levels at just one of the roost sites of Roebuck Bay would increase energetic costs substantially, and could easily reach the point at which feeding areas accessed from this roost cannot be used without incurring a net energy deficit. Roost availability can therefore limit access to feeding areas and hence limit population size. Adequate provision and management of roost sites is accordingly an important consideration in conservation of sites used by coastal shorebirds. (c) 2006 Elsevier Ltd. All rights reserved

Shorebirds as integrators and indicators of mudflat ecology

Shorebirds are major, but thus far under-acknowledged, players in mudflat food webs and associated physio-chemical processes. Mud is a critical habitat type for shorebirds, offering a multi-dimensional matrix of feeding opportunities through space and time. Shorebirds have evolved a spectrum of foraging modes with associated morphologies, and sensory and physiological adaptations which exploit these foraging opportunities. Although shorebirds are mud specialists and sentinels of mudflat ecosystem functioning, they have not yet been well integrated into the “mud club”. In this chapter, we highlight the key roles shorebirds play in food webs, and in physical and chemical processes within mudflat ecosystems. We illustrate how shorebird distribution and behaviour provides a mirror of mudflat ecology because their foraging behaviour reflects the underlying ecological conditions, including temporal and spatial patterns in food/community structure in and across mud. In particular, shorebirds may be important indicators of essential fatty acid production by diatoms in epibenthic biofilm fields covering muddy intertidal flats, especially in estuaries. We conclude by highlighting the major challenges facing shorebirds today and call for a paradigm shift in shorebird conservation, based on recreating and restoring intertidal mud ecosystems

Reconstructing palaeoflyways of the late Pleistocene and early Holocene Red Knot Calidris canutus

Bird migration systems must have changed dramatically during the glacial–interglacial cycles of the Pleistocene and as novel habitats became available since the last glacial maximum. This study combines molecular dating of population divergence times with a review of polar-centred palaeovegetation and intertidal habitats world-wide to present a hypothesis for the evolution of Red Knot Calidris canutus flyways. Divergence dates from coalescent analysis of mitochondrial control region sequences indicate that C. c. canutus diverged from the most recent common ancestor (MRCA) of Red Knots about 20000 (95% CI 60000–4000) years ago. About 12000 (95% CI 45000–3500) years ago this MRCA diverged into two lineages, now represented by the North American breeding C. c. roselaari, C. c. rufa and C. c. islandica and the Siberian breeding C. c. piersmai and C. c. rogersi, respectively. Divergence times of these two Siberian breeding subspecies are about 6500 (95% CI 25000–1000) years ago, and populations of the North American breeding subspecies are estimated to have diverged within about the last 1000 years. These divergence times suggest that all ancestral populations of knots emerged within the last glacial period of the Pleistocene via an eastward expansion into North America. This scenario implies that, contrary to contemporary opinions, C. c. islandica was not recently derived from C. c. canutus despite the fact that they are morphologically similar and that their contemporary migration routes overlap in the Wadden Sea. Instead, C. c. islandica is most closely related to the other North American breeding subspecies C. c. roselaari and C. c. rufa. Thus, C. c. islandica only recently pioneered its current migration route to Europe, following the amelioration of winter conditions in the Wadden Sea and the formation of staging habitat in Iceland. This implies that, in Red Knots at least, the Greenland/Iceland migratory route was established very recently from breeding grounds in the Americas to wintering grounds in Europe and not vice versa as previously believed.

Seasonal variation in rest-activity patterns in barnacle geese:Are measurements of activity a good indicator of sleep-wake patterns?

Sleep is a widely spread phenomenon in the animal kingdom and is thought to serve important functions. Yet, the function of sleep remains an enigma. Studies in non-model animal species in their natural habitat might provide more insight into the evolution and function of sleep. However, polysomnography in the wild may not always be an option or first choice and some studies may need to rely on rest–activity recordings as a proxy for sleep and wakefulness. In the current paper, we analyzed how accelerometry-based activity data correlate with electroencephalogram (EEG)-based sleep–wake patterns in barnacle geese under seminatural conditions across different seasons. In winter, the geese had pronounced daily rhythms in rest and activity, with most activity occurring during the daytime. In summer, activity was more spread out over the 24 h cycle. Hourly activity scores strongly correlated with EEG-determined time awake, but the strength of the correlation varied with phase of the day and season. In winter, the correlations between activity and waking time were weaker for daytime than for night-time. Furthermore, the correlations between activity and waking during daytime were weaker in winter than in summer. During daytime in winter, there were many instances where the birds were awake but not moving. Experimental sleep deprivation had no effect on the strength of the correlation between activity scores and EEG-based wake time. Overall, hourly activity scores also showed significant inverse correlation with the time spent in non-rapid eye movement (NREM) sleep. However, correlation between activity scores and time spent in REM sleep was weak. In conclusion, accelerometry-based activity scores can serve as a good estimate for time awake or even the specific time spent in NREM sleep. However, activity scores cannot reliably predict REM sleep and sleep architecture