Protandry is a widespread life-history phenomenon describing how males precede females at the site or state of reproduction. In migratory birds, protandry has an important influence on individual fitness, the migratory syndrome, and phenological response to climate change. Despite its significance, accurate analyses on the dynamics of protandry using data sets collected at the breeding site, are lacking. Basing our study on records collected during two time periods, 1979 to 1988 and 2006 to 2016, we aim to investigate protandry dynamics over 38 years in a breeding population of willow warblers (Phylloscopus trochilus). Change in the timing of arrival was analyzed in males and females, and protandry (number of days between male and female arrival) was investigated both at population level and within breeding pairs. Our results show advancement in the arrival time at the breeding site in both sexes, but male arrival has advanced to a greater extent, leading to an increase in protandry both at the population level and within breeding pairs. We did not observe any change in sex ratio that could explain the protandry increase, but pronounced temperature change has occurred and been reported in the breeding area and along the migratory route. Typically, natural selection opposes too early arrival in males, but given warmer springs, this counteracting force may be relaxing, enabling an increase in protandry. We discuss whether our results suggest that climate change has induced sex-specific effects, if these could be evolutionary and whether the timing of important life-history stages such as arrival at the breeding site may change at different rates in males and females following environmental shifts.

Aim: The configuration of the earth's landmasses influences global weather systems and spatiotemporal resource availability, thereby shaping biogeographical patterns and migratory routes of animals. Here, we aim to identify potential migratory barriers and corridors, as well as general migration strategies within the understudied Indo-European flyway. Location Europe, Central Asia. Major taxon studied Common rosefinches.

Methods: We used a combination of theoretical optimization modelling and empirical tracking of Common Rosefinches (Carpodacus erythrinus) breeding across a large latitudinal gradient in Europe. First, we identified optimal migration routes driven by wind and resource availability along the Indo-European flyway. Second, we tracked rosefinches from five breeding populations using light-level geolocators. Finally, we compared to what extent empirical tracks overlapped with the modelled optimal routes.

Results: In autumn, theoretical wind driven migration routes formed a broad-front corridor connecting Europe and the Indian Subcontinent while the theoretical resource driven routes formed a distinct north-south divide. The latter pattern also reflected the rosefinch tracks with all but the most southerly breeding birds making a northern detour towards non-breeding sites in Pakistan and India. In spring, the resource availability model predicted a similar migratory divide, however, the southern route seemed relatively more favourable and closely matched with the optimal wind driven migration routes. Spring tracking data showed larger overlap with the modelled wind driven migration routes compared to the resource driven routes.

Main conclusions: Optimal wind and resource driven migration routes along the Indo-European flyway are seasonally specific and to a large extend do not overlap with one another. Under these conditions, migratory birds adopt seasonally distinct migration strategies following energy minimization strategy in autumn, driven by resource availability, and time minimizing strategy in spring, driven by wind conditions. Our optimal migration models can be applied worldwide and used to validate against empirical data to explain large-scale biogeographic pattern of migratory animals.

The return of individual birds to a specific area in successional years, i.e. philopatry, is a remarkable behavioural trait. Here we report on the remarkably reversed: the complete absence of returning individuals of a migratory passerine with otherwise pronounced philopatry. At a high latitude study site in Abisko (68°32ʹN, 18°80ʹE) in northern Sweden none of the banded adult willow warblers Phylloscopus trochilus returned to breed 2011–2014. This is in stark contrast to all other reports in the literature and also to our two southern study sites (at 56°56ʹN, 18°10ʹE and at 58°94ʹN, 17°14ʹE) where 18–38% of adults returned. We investigated this aberrant pattern found in Abisko by analysing three parameters known to influence philopatry; nest predation, breeding success and breeding density, and predicted that absence of philopatry should co-occur with low breeding success, low breeding density and/or high nest predation. The results did not corroborate this, except that breeding density was lower at Abisko (49–71 pairs km^–2) than at the southern sites (106 pairs km^–2, 101 pairs km^–2). Instead, we suggest the hypothesis that the absence of philopatry is caused by an influx of southern, dispersal-prone individuals deploying another breeding strategy and that this intra-specific range expansion is enabled by milder climate and low population density.

Only few bird species from Western Europe migrate eastward to wintering areas in South Asia, and little is known about this migratory flyway. The Common Rosefinch has in the past century expanded its breeding range westward to include Western Europe and migrate along this flyway to wintering sites in South Asia. This is the first study describing the migration routes of Common Rosefinches between Europe and Asia in detail, revealed by light level geolocators. The rosefinches showed loop-migration with more northerly routes in autumn than in spring, possibly in order to shorten the flight over the Central Asian deserts, which are very inhospitable at this time of the year. In spring the deserts are less dry and richer in vegetation, which may have supported the more southerly routes. During autumn migration the birds used several staging sites in Central Asia for prolonged periods. Although the birds passed over mountain regions at this time, which potentially act as barriers to them, the length of the stops seem unrealistically long for only fuel deposition. Instead, this suggests that the birds temporarily suspended migration to take advantage of abundant and predictable food sources in this region. During spring migration the birds made a few longer stops while still in north India or Central Asia, before migrating at fast speeds towards the breeding grounds. The birds covered 4–5000 km with only very short stopovers and thus most of the fuel used on spring migration must have been accumulated in Asia. Our results thus indicate that Central Asia, and north India, are important staging areas for this species in both autumn and spring. During winter, birds used two sites located several hundred kilometres apart, and relocation was probably a response to local food availability.

Climate change can influence many aspects of avian phenology and especially migratory shifts and changes in breeding onset receive much research interest in this context. However, changes in these different life-cycle events in birds are often investigated separately and by means of ringing records of mixed populations. In this long-term study on the willow warbler Phylloscopus trochilus, we investigated timing of spring and autumn migration in conjunction with timing of breeding. We made distinction among individuals with regard to age, sex, juvenile origin and migratory phase. The data set comprised 22-yr of ringing records and two temporally separated data sets of egg-laying dates and arrival of the breeding population close to the ringing site. The results reveal an overall advancement consistent in most, but not all, phenological events. During spring migration, early and median passage of males and females became earlier by between 4.4 to 6.3 d and median egg-laying dates became earlier by 5 d. Male arrival advanced more, which may lead to an increase in the degree of protandry in the future. Among breeding individuals, only female arrival advanced in timing. In autumn, adults and locally hatched juvenile females did not advanced median passage, but locally hatched juvenile males appeared 4.2 d earlier. Migrating juvenile males and females advanced passage both in early and median migratory phase by between 8.4 to 10.1 d. The dissimilarities in the response between birds of different age, sex and migratory phase emphasize that environmental change may elicit intra-specific selection pressures. The overall consistency of the phenological change in spring, autumn and egg-laying, coupled with the unchanged number of days between median spring and autumn migration in adults, indicate that the breeding area residence has advanced seasonally but remained temporally constant.

Migratory birds use stopovers to replenish their fuel reserves and they generally spend more time at stopover sites than theydo in actual fl ight. When arriving at a new stopover site birds may need to search extensively to fi nd a suitable feeding areaand this search and settling period may aff ect the duration of stopover. Stopover behaviour can thus have profound eff ectson the migratory programme and studies on stopover behaviour are important to understand migratory strategies. Wefollowed 51 fi rst-year garden warblers Sylvia borin with radio-transmitters at an autumn stopover site on the island ofGotland in southern Sweden. Our aim was to determine the distance birds relocated from the coastal capture site whensearching for an area to settle in, and also to establish the duration of stopover and put it in relation to refuelling rate byrecapturing a subset of the radio-tracked individuals. Sixteen birds made an extended stopover ( 2 d), relocated inlandfrom the capture site and settled on average 5.6 km from the capture site, with the longest recorded relocation being fourteenkilometres. Birds that relocated nocturnally settled in areas further away than birds that relocated diurnally. Th irteenbirds that continued migration after a short stop carried larger fuel stores than birds that stopped over longer and theyremained close to the capture site until departure. Th ree birds were re-trapped and showed high fuelling rates, between0.3 and 1.1 g d 1 . Th ey left the stopover site with fuel loads between 40 – 56 percent of lean body mass, which possiblywould have allowed them to reach the Mediterranean area without additional refuelling stops.

Small eyespots on butterflies have long been thought to deflect attacks, and birds are the presumptive drivers selecting for these patterns; however, evidence of this function is still ambiguous. Marginal eyespots typically consist of a UV-reflective white pupil, surrounded by one black and one yellowish ring. We have recently shown that Cyanistes caeruleus (blue tits) attack such eyespots, but only under low light intensities with accentuated UV levels: the increased salience of the eyespots relative to the rest of the butterfly probably explains this result. Possibly the background against which the butterfly is concealed may deceive birds to make similar errors. We therefore presented speckled wood butterflies decorated with eyespots (or controls without eyespots) to C.caeruleus against two backgrounds: oak and birch bark. Our results show that: (1) eyespots, independent of background, were effective in deflecting attacks; (2) the time elapsed between a bird landing and the attack was interactively dependent on the background and whether the butterfly bore an eyespot; and (3) the speed at which a butterfly was attacked predicted the outcome, with faster birds being more prone to errors than slower birds. This underscores a speedaccuracy trade-off in the predators, and that background plays a role in the defensive qualities of marginal eyespots.(c) 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 109, 290297.

Large conspicuous eyespots have evolved in multiple taxa and presumably function to thwart predator attacks. Traditionally, large eyespots were thought to discourage predator attacks because they mimicked eyes of the predators' own predators. However, this idea is controversial and the intimidating properties of eyespots have recently been suggested to Amply be a consequence of their conspicuousness. Some lepidopteran species include large eyespots in their antipredation repertoire. In the peacock butterfly, Mathis io, eyespots are typically hidden during rest and suddenly exposed by the butterfly when disturbed. Previous experiments have shown that small wild passerines are intimidated by this display. Here, we test whether eyespots also intimidate a considerably larger bird, domestic fowl, Gallus gallus domesticus, by staging interactions between birds and peacock butterflies that were sham-painted or had their eyespots painted oven Our results show that birds typically fled when peacock butterflies performed their display regardless of whether eyespots were visible or painted over. However, birds confronting butterflies with visible eyespots delayed their return to the butterfly, were more vigilant, and more likely to utter alarm calls associated with detection of ground-based predators, compared with birds confronting butterflies with eyespots painted over. Because production of alarm calls and increased vigilance are antipredation behaviors in the fowl, their reaction suggests that eyespots may elicit fear rather than just an aversion to conspicuous patterns. Our results, therefore, suggest that predators perceive large lepidopteran eyespots as belonging to the eyes of a potential predator.

The wolf (Canis lupus) is classified as endangered in Sweden by the Swedish Species Information Centre, which is the official authority for threat classification. The present population, which was founded in the early 1980s, descends from 5 individuals. It is isolated and highly inbred, and on average individuals are more related than siblings. Hunts have been used by Swedish authorities during 2010 and 2011 to reduce the population size to its upper tolerable level of 210 wolves. European Union (EU) biodiversity legislation requires all member states to promote a concept called “favourable conservation status” (FCS) for a series of species including the wolf. Swedish national policy stipulates maintenance of viable populations with sufficient levels of genetic variation of all naturally occurring species. Hunting to reduce wolf numbers in Sweden is currently not in line with national and EU policy agreements and will make genetically based FCS criteria less achievable for this species. We suggest that to reach FCS for the wolf in Sweden the following criteria need to be met: (1) a well-connected, large, subdivided wolf population over Scandinavia, Finland, and the Russian Karelia-Kola region should be reestablished, (2) genetically effective size (N_e) of this population is in the minimum range of N_e = 500–1000, (3) Sweden harbors a part of this total population that substantially contributes to the total N_e and that is large enough to not be classified as threatened genetically or according to IUCN criteria, and (4) average inbreeding levels in the Swedish population are <0.1.

El lobo (Canis lupus) está clasificado como en peligro en Suecia por el Centro Sueco de Información de Especies, que es la autoridad oficial para la clasificación de amenazas. La población actual, que fue fundada a principio de la década de 1980, desciende de 5 individuos. Esta aislada y tiene altos niveles de endogamia, y en promedio los individuos están más relacionados que los hermanos. Durante 2010 y 2011, las autoridades suecas han usado la cacería para reducir el tamaño de la población hasta su nivel superior tolerable de 210 lobos. La legislación de biodiversidad en la Unión Europea (UE) requiere que todos los países miembros promuevan un concepto denominado “estatus de conservación favorable” (ECF) para una serie de especies incluyendo al lobo. La política nacional sueca establece el mantenimiento de poblaciones viables, con niveles suficientes de variación genética, de todas las especies que ocurren naturalmente. La cacería para reducir el número de lobos en Suecia no se alinea con los acuerdos políticos nacionales y de la UE y es una limitante para que se cumplan los criterios para un ECF basado genéticamente. Sugerimos que para alcanzar el ECF para el lobo en Suecia se requiere cumplir con los siguientes criterios: (1) el restablecimiento de una población grande, subdividida y bien conectada en Escandinavia, Finlandia y la región Karelia-Kola de Rusia, (2) tamaño efectivo genéticamente (N_e) de esta población en el rango mínimo de N_e = 500–1000. (3) Suecia tiene una parte de esta población total que contribuye sustancialmente al N_e total, y que es lo suficientemente grande para no ser clasificada como amenazada genéticamente o de acuerdo con los criterios de la UICN, y (4) los niveles promedio de endogamia en la población sueca son <0.1.

Morphological and behavioural traits can serve as anti-predator defence either by reducing detection or recognition risks, or by thwarting initiated attacks. The latter defence is secondary and often involves a 'startle display' comprising a sudden release of signals targeting more than one sensory modality. A suggested candidate for employing a multimodal defence is the peacock butterfly, Inachis io, which, by wing-flicking suddenly, produces sonic and ultrasonic sounds and displays four large eyespots when attacked. The eyespots make small birds retreat, but whether the sounds produced thwart predator attacks is largely unknown. Peacocks hibernate as adults in dark wintering sites and employ their secondary defence upon encounter with small rodent predators during this period. In this study, we staged predator-prey encounters in complete darkness in the laboratory between wild mice, Apodemus flavicollis and Apodemus sylvaticus, and peacocks which had their sound production intact or disabled. Results show that mice were more likely to flee from sound-producing butterflies than from butterflies which had their sound production disabled. Our study presents experimental evidence that the peacock butterfly truly employs a multimodal defence with different traits targeting different predator groups; the eyespots target birds and the sound production targets small rodent predators.