In 1950, Rensch first described that in groups of related species, sexual size dimorphism is more pronounced larger species. This widespread and fundamental allometric relationship now commonly referred to as ‘Rensch's rule’. However, despite numerous recent studies, we still do not have a general explanation for this allometry. Here report patterns allometry over 5300 bird species demonstrate Rensch's rule driven by correlated evolutionary change females directional selection on males....

Body size is an important characteristic of animals, influencing physiology, life histories, and general ecology. Hence, it often needs to be taken into account even if the aim test for relationships among other traits. We provide a comprehensive data set on avian body sizes that would useful future comparative studies biology. extracted species-specific measurements male female mass, wing length, tarsus bill tail length from major ornithological text books some sources covering bird species...

Boreal regions with a mild winter climate, such as the western coastal area of Norway, may hold number wintering passerine birds, in spite short day length mid winter. To determine whether birds under conditions were able to use artificial light increase their activity periods, day-time and night-time bird censuses done from October March residential Bergen, along roads lit by street lights. Situated at latitude 60°N, has 18 hours darkness Twenty-four species recorded. Of these European...

Summary The incubation‐limitation hypothesis states that clutch size in shorebirds is constrained by the ability to incubate more than four eggs successfully. In order test predictions from this hypothesis, clutches of northern lapwings ( Vanellus vanellus ) were here experimentally increased and reduced one egg at onset incubation. Parental behaviour, incubation time, hatching synchrony, viability, success body condition hatchlings was compared with unmanipulated clutches. Nest desertion...

Sexual size dimorphism (SSD) is often assumed to be driven by three major selective processes: (1) sexual selection influencing male and thus mating success, (2) fecundity acting on females (3) inter-sexual resource division favouring different in males reduce competition for resources. should particularly strong species that exhibit lek polygyny, since success highly skewed such species. We investigated whether these processes are related SSD evolution grouse allies (Phasianidae)....

In a population of Lapwings Vanellus vanellus studied for 5 years near Bergen, southwester Norway, 23–41% the males were polygynous, having two and sometimes three mates, whereas 50–77% monogamous 0–21% remained unmated. Bachelors held territories in or immediately adjacent to study area each years. As predicted from Polygyny Threshold model, primary females generally laid eggs earlier than females, but overlap laying dates was substantial between these classes. The number start breeding on...

How individual birds schedule their movements and use different sites during the non‐breeding season are fundamental issues in avian migration ecology, studies have often revealed strong seasonal variation such strategies. Using geolocators we tracked Common Ringed Plovers Charadrius hiaticula from northern Norway to West Africa back assess whether there were differences migratory speed, duration stopover between autumn spring used multiple season. Although pace of was similar spring, length...

Capsule Red-spotted Bluethroats Luscinia s. svecica from two European breeding populations spent the boreal winter on Indian sub-continent.Aim Tracking migration of Europe to hitherto unknown non-breeding areas and back.Methods Light-level geolocators were deployed male at sites in Czech Republic (n = 10) Norway 30). Recorded light intensity data used estimate locations phenology during annual cycle.Results India 3) Pakistan 1), average more than 6000 km their areas. Autumn started August 1)...

Abstract Increasing levels of global environmental change may have negative impacts on fertility and embryo viability in animals that could explain a recently reported increase hatching failure bird eggs across the globe. Here we test this relationship again by analyzing dataset containing almost twice as many species covering longer time period than earlier works (n = 431 during 1906–2022). We also tested for effects Red List status population size. found rates combined group currently...

Nest-dwelling ectoparasitic arthropods may have detrimental effects on avian breeding success and fitness. Birds should therefore be selected to avoid nest sites where the risk of being infested by ectoparasites is high. However, studies testing this hypothesis produced mixed results. We performed an experiment in south Norway test whether Pied Flycatchers Ficedula hypoleuca select site according presence ectoparasites. used artificial boxes which had all been successfully conspecifics...

Abstract Although geolocator tracking of small passerines has become commonplace in the last two decades, this tool is still underutilized for gathering natural history data migration many species. Common Whitethroat ( Curruca communis ) one most numerous Afro-Palearctic migrants. However, our knowledge species’ ecology remains limited. Here, we combine ring-recovery analyses with to describe routes and population-specific non-breeding areas long-distance migrant. Linkages between breeding,...

In bird species where males incubate but are smaller than females, egg size may be constrained by male body size, and hence ability to the eggs. Using data from 71 such shorebird species, we show that decreases as degree of female-biased sexual dimorphism increases, after controlling for female mass. Relative was not related mean clutch size. However, when mating system, relationship between relative only significant in polyandrous species. The relatively small eggs socially shorebirds have...

Exploring the patterns of genetic structure in context geographical and phenotypic variation is important to understand evolutionary processes involved speciation. We investigated population subspecies differentiation Common Ringed Plover Charadrius hiaticula, a high latitude wader that breeds arctic temperate zones from northeast Canada across Eurasia Russian Far East. Three subspecies, tundrae psammodromus, are currently widely recognised, whereas fourth kolymensis, has been proposed based...

Information on habitat, nest placement, phenology and clutch size in Red-backed Shrikes Lanius collurio was collected from a total of 71 nests southern Norway during 1995-2009.In this area, which is situated at the north-western limit species' distribution, breeding predictable clear-cuts pine Pinus sylvestris forest where junipers Juniperus communis made up large part shrub layer.This contrasts with previous descriptions typical shrike habitat focused availability young spruce Picea abies...

By using morphometric data and geolocator tracking we investigated fuel loads spatio‐temporal patterns of migration non‐breeding in Temminck's stints Calidris temminckii . Body masses captured at autumn stopover sites from Scandinavia to northern Africa were generally not much higher than during breeding did vary geographically. Thus, expected migrating make several stopovers either circumventing the Sahara desert with low or fuelling north African before crossing. Geolocation revealed that...

Abstract In biparental Charadriinae plovers, male and female incubation duties often resemble daily routines, with males typically incubating at night females during the day. By analysing behaviour in three Arctic populations of Common Ringed Plover Charadrius hiaticula , we show that these diel routines are lost 24-h sunlight Arctic. contrast, a non-Arctic population East Scotland exhibited significant dominating late afternoon night, early morning midday hours. These patterns suggest clear...

Abstract This study focuses on possible sources of egg size variation in the northern lapwing Vanellus vanellus , a polygynous shorebird with more variable male than female reproductive success. From hypothesis that birds allocate resources into eggs to improve their sons' abilities compete for mates, were predicted be larger eggs, and proportion sons was increase mean volume clutches. However, no differences between found. Corresponding earlier reports species, positively correlated body...

Abstract Previous studies of sex roles in the polygynous Northern Lapwing Vanellus vanellus have shown that males incubate less than females, perhaps suggesting sexual selection is important shaping parental behaviour this species. The purpose study was to (1) examine for first time possibility compensate low diurnal nest attentiveness by increasing their nocturnal assistance and (2) evaluate hypotheses individual breeding quality determines incubation lapwings. Males were never found...

Abstract In Norway, a positive relationship between spring numbers of lesser spotted woodpecker (Dendrocopos minor) and previous June temperatures has been interpreted as an effect on survival reproduction during the breeding season. This article considers possibility that are related to abundance moth Argyresthia goedartella in current year. Larvae pupae A. important food for woodpeckers early when few other surface-living invertebrates available. The occurrence this depends flowering birch...

In water rails Rallus aquaticus , northern and eastern populations are migratory while southern western sedentary. Few details known about the annual cycle of this elusive species. We studied movements breeding in from southernmost Norway where species occurs year‐round. Colour‐ringed wintering birds occurred only occasionally at study site summer, vice versa. Geolocator tracks revealed that (n = 10) migrated eastwards spring to breed on both sides Baltic Sea, whereas a single bird wintered...

In systems with bi‐parental care, sexual conflict theory states that a transition from monogamy to polygyny should increase fitness prospects for males and reduce of resident females. Behavioural observations Northern Lapwings Vanellus vanellus suggested females try monopolize their breeding resources by attacking prospecting secondary status, commonly respond intervening on behalf the four territories successfully defended monogamous in nine made at least one successful eviction before...