Hedh L.,Lund University |
Hedenstrom A.,Lund University |
Hedenstrom A.,Ottenby Bird Observatory
Ardea | Year: 2016
In this study we compare autumn migration strategies in two subspecies of the Common Ringed Plover Charadrius hiaticula in the southern Baltic Sea. This species exhibits a leap-frog migration pattern, whereby northerly breeding populations (C. h. tundrae; henceforth tundrae) migrate past the whole range of the southern population (C. h. hiaticula; henceforth hiaticula). Hiaticula migrates the shortest distance and is hypothesised to minimize energy spent on migration, whereas tundrae is hypothesized to minimize time, because a longer migration imposes time constraints upon other stages of a migrant's life history, such as moult and breeding. We use biometric data collected at Ottenby Bird Observatory, southern Öland, Sweden, between 1946-2012, to test whether each subspecies demonstrates characteristics associated with either an energy- or time-minimized migration. We used the decline in wing and total-head length over the season to distinguish the subspecies. Hiaticula migrated earlier in the season (July-mid August) compared to tundrae (late July-late September). Also the relative timing of age groups between the two subspecies differed. Juvenile and adult hiaticula migrated synchronized in time, whereas tundrae had two main periods of passage for adults (earlier) and juveniles (later). The timing fits that of other studies and gives complementary information about the passage in Europe. Juvenile tundrae showed a positive trend of observed fuel loads as the season progressed, whereas the other groups did not. Daily fuelling rates within the same season were low compared to other wader species that use Ottenby as a stopover and no difference between subspecies was found. However, tundrae stopped over for a shorter time compared with hiaticula. There was no difference in average migration speed between the subspecies, although tundrae had a higher maximum speed. There was large variation in yearly numbers between age classes in the two subspecies. In hiaticula the yearly average was 8 adults and 37 juveniles. The ratio of juvenile to adult tundrae on the other hand was almost 1:1, indicating equal use of Ottenby as stop over site in autumn. No trends in observed fuel loads over the season in hiaticula are consistent with an energy minimizing migration. As for tundrae, a shorter stopover time compared to hiaticula and a positive relationship between observed fuel load and time, are consistent with time minimizing migration. However, there are many uncertainties and more studies of migratory behaviours at several sites along the migration route are needed to understand the differences in migration strategies in this species.
Moller A.P.,University Paris - Sud |
Christiansen S.S.,Ottenby Bird Observatory |
Mousseau T.A.,University of South Carolina
Behavioral Ecology | Year: 2011
Adults of many species display extravagant sexual signals during the reproductive season, apparently evolved as a means of attracting mates or repelling potential competitors, thereby inadvertently also attracting the attention of predators. Many studies have shown predation costs of sexual display. Therefore, we should expect species with the most exaggerated signals to have evolved antipredator behavior that reduces or eliminates predation costs of sexual signaling but also to have evolved behavior that allows for escape from a predator once captured. We quantified 6 aspects of escape behavior in 2105 free-living birds belonging to 80 species when handled after capture for banding. Escape behavior was species specific as demonstrated by significant consistency in behavior among individuals. Escape behavior was significantly related to susceptibility to predation by cats Felis catus and goshawks Accipiter gentilis, showing that escape behavior is under current selection. Escape behavior was related to the ease of feather loss estimated in a previous study but also to the frequency of tailless individuals recorded in the field. Thus, escape behavior reported here was cross-validated against other aspects of antipredator behavior shown to reflect risk of predation. Aspects of escape behavior differed significantly between males and females (biting, fear screams, and feather loss). Sexually dichromatic species differed in escape behavior from monochromatic species by having a reduced frequency of fear screams and increased tonic immobility. These findings suggest that exposure to risk of predation has modified escape behavior in relation to sexual coloration. © 2011 The Author.
Iwajomo S.B.,Ap Leventis Ornithological Research Institute |
Hedenstrom A.,Lund University |
Hedenstrom A.,Ottenby Bird Observatory
Ringing and Migration | Year: 2011
Current knowledge of the migration of the Common Sandpiper Actitis hypoleucos is still limited. The species has been ringed at Ottenby Bird Observatory, southeast Sweden, since 1947, allowing for analyses of long-term and seasonal trends. We analysed trapping data for 1,942 adults and 3,290 juveniles with respect to patterns in phenology, morphometrics, and fuel load. We used fuel loads to estimate potential flight ranges. The number of adult birds trapped increased significantly over the years, whereas juveniles declined. Median passage date was 27 July and 7 August for adult and juvenile birds respectively, and juveniles showed a significant advancement in median passage date. Mean fuel loads were 28.8% and 27.8% of lean body mass (LBM) for adult and juvenile birds respectively, while maximum fuel load was as high as 98.7% in juveniles and 105.4% in adults. Fuel load increased significantly with date in juveniles but declined in adults. Advancement in passage of juvenile birds over the year is possibly due to climate change. Also, the average adult and juvenile are theoretically capable of a direct flight to central France; a major recovery area. Fuel load patterns suggest that in autumn, the two age classes use different migration strategies. © 2011 British Trust for Ornithology.
Hellstrom M.,Ottenby Bird Observatory |
Waern M.,Carl Malmstens Vag 21
British Birds | Year: 2011
The Common Stonechat Saxicola torquatus is a widespread breeding species in the Palearctic region. This paper discusses the reliability of characters that enable birds from Europe (S. t rubkola) to be separated from those breeding in western Siberia and central Asia (S. t maurus), particularly during the breeding season when differences become subtle. The current understanding of plumage variability within and between these races is discussed, and some gaps in our knowledge of Siberian birds are addressed. Emphasis is placed upon assessing the validity of the different characters. The timing and extent of moult and wear are crucial to the understanding of these characters and of how they can affect appearance over time. Other Palearctic races are discussed where relevant. Careful observation and attention to detail are essential when faced with a potential maurus in Europe in spring but individuals of both sexes should provide sufficient clues for identification, if seen well. © British Birds 104. May 2011.
Snoeck C.J.,Institute of Immunology |
Adeyanju A.T.,University of Jos |
Adeyanju A.T.,University of Ibadan |
Owoade A.A.,University of Ibadan |
And 5 more authors.
Applied and Environmental Microbiology | Year: 2013
In West and Central Africa, virulent Newcastle disease virus (NDV) strains of the recently identified genotypes XIV, XVII, and XVIII are enzootic in poultry, representing a considerable threat to the sector. The increasing number of reports of virulent strains in wild birds at least in other parts of the world raised the question of a potential role of wild birds in the spread of virulent NDV in sub-Saharan Africa as well. We investigated 1,723 asymptomatic birds sampled at live-bird markets and sites important for wild-bird conservation in Nigeria and 19 sick or dead wild birds in Côte d'Ivoire for NDV class I and II. Typical avirulent wild-type genotype I strains were found in wild waterfowl in wetlands in northeastern Nigeria. They were unrelated to vaccine strains, and the involvement of inter- or intracontinental migratory birds in their circulation in the region is suggested. Phylogenetic analyses also revealed that genotype VI strains found in pigeons, including some putative new subgenotype VIh and VIi strains, were introduced on multiple separate occasions in Nigeria. A single virulent genotype XVIII strain was found in a dead wild bird in Côte d'Ivoire, probably as a result of spillover from sick poultry. In conclusion, screening of wild birds and pigeons for NDV revealed the presence a variety of virulent and avirulent strains in West Africa but did not provide strong evidence that wild birds play an important role in the spread of virulent strains in the region. © 2013, American Society for Microbiology.
Cox D.T.C.,University of St. Andrews |
Cox D.T.C.,Ap Leventis Ornithological Research Institute |
Brandt M.J.,BioConsult SH |
Mcgregor R.,Scottish Natural Heritage |
And 5 more authors.
Ibis | Year: 2011
Birds in the northern hemisphere usually increase mass reserves in response to seasonal low temperatures and shorter day length that increase foraging unpredictability and so starvation risk. In the lowland tropics, relatively low temperatures and short day lengths are absent and so the risk of starvation may be reduced, leading to much smaller seasonal effects on mass. Nevertheless, other factors such as high temperatures and water and food availability may vary greatly between tropical wet and dry seasons, leading to variable starvation risk and seasonal mass effects. Using data collected from 47 species of birds caught over a 10-year period in a tropical savannah region in West Africa we tested for seasonal variation in mass in response to a predictable, strongly seasonal tropical climate. Many species (91%) showed seasonal variation in mass, and this was often in a clear annual pattern that was constant across the years. Many species (89%) varied their mass in response to seasonally predictable rainfall. Annual variation in mass was also important (45% of species). Relatively few species (13%) had a seasonal pattern of mass variation that varied between years. Feeding guild or migratory status was not found to affect seasonal or annual mass variation. Seasonal mass change was on average 8.1% across the 21 species with a very large sample size and was comparable with both northern and southern temperate species. Our study showed that biologically significant consistent seasonal mass variation is common in tropical savannah bird species, and this is most likely in response to changing resource availability brought about by seasonal rainfall and the interrupted foraging response due to the constraints of breeding. © 2011 The Authors. Ibis © 2011 British Ornithologists' Union.
Spring fuelling by arctic Dunlins Calidris a. alpina in the southern Baltic and the potential role of a changing climate [Fettupplagring under våren hos kärrsnäppa Calidris a. alpina i södra Östersjön och möjliga följder av en klimatändring]
Stedt J.,Linnaeus University |
Stedt J.,Ottenby Bird Observatory |
Lindstrom A.,Lund University
Ornis Svecica | Year: 2012
In spring, Dunlins Calidris a. alpina put on substantial fuel stores in the North Sea region before a long flight to breed in northwest Russia. There are hitherto no welldescribed fuelling sites in the Baltic region. In May and early June in 2004-2010 we trapped more than 1000 Dunlins at Ottenby, south-east Sweden. Most birds carried substantial fuel loads already when first trapped (much more than in autumn) and, more importantly, 37 within-season re-traps increased in mass at an average rate of 1.2 g/d. This corresponds to a fuelling rate of about 2.6 % of lean body mass per day, among the highest recorded for this species. Stopover times were short; only 3.5 % of the birds were re-trapped and they stayed on average only 2.2 days. Since the late 1970s, increasing numbers of Dunlins stop over at successively earlier dates. This coincides with an increase in spring temperature of 1.1-2.0°C in 1977-2010. Possibly, a warming climate has facilitated and selected for a gradual shift of the final fuelling sites closer towards the breeding grounds.
Stevens M.C.,University of St. Andrews |
Stevens M.C.,University of Jos |
Ottosson U.,University of Jos |
Ottosson U.,Ottenby Bird Observatory |
And 4 more authors.
Ostrich | Year: 2013
Despite widespread interest in life histories and the comparison of parameters between tropical and temperate regions, there are still relatively few multispecies studies assessing annual survival in Afrotropical species. We used data from systematic mist-netting of savanna birds in Nigeria, between 2001 and 2008, to estimate survival for 40 Afrotropical bird species. Best-supported models were those incorporating constant survival (27 of 40) or the effects of transience (13 of 40). Survival ranged from 0.269 to 0.948 (mean ± SE = 0.64 ± 0.02), varied within and between families, and showed a positive relationship with mass in passerines. Survival was highest in the insectivorous Malaconotidae (0.79 ± 0.13) and lowest in the granivorous Estrildinae (0.51 ± 0.04). This pattern was also evident in a comparison of survival between guilds (highest in insectivores and lowest in granivores) suggesting that these species encounter seasonal starvation risks or exhibit a seasonal response to water availability, i.e. emigration from the study area leading to reduced site fidelity and lower apparent survival. Our estimates of adult survival are higher than those previously obtained from this site, comparable with those from other Afrotropical studies (i.e. >0.60) and higher than those from temperate zones (0.53 ± 0.01, n = 79). © 2013 Copyright NISC (Pty) Ltd.
Iwajomo S.B.,Copenhagen University |
Iwajomo S.B.,University of Jos |
Stervander M.,Lund University |
Stervander M.,Ottenby Bird Observatory |
And 3 more authors.
Ringing and Migration | Year: 2013
Long-term ringing data are useful for understanding population trends and migration strategies adopted by migratory bird species during migration. To investigate the patterns in demography, phenology of migration and stopover behaviour in Wood Sandpipers Tringa glareola trapped on autumn migration at Ottenby, southeast Sweden, in 1947-2011, we analysed 65 years of autumn ringing data to describe age-specific trends in annual trappings, morphometrics and phenology, as well as fuel deposition rates and stopover duration from recapture data. We also analysed the migratory direction of the species from recovery data. Over the years, trapping of both adults and juveniles has declined significantly. Median trapping dates were 10 July for adults and 6 August for juveniles. Average migration speed of juvenile birds was 58.1 km d-1. Adults stayed on average 3.5 days and juveniles 5.2 days, with average fuel deposition rates of 2.5 and 0.7 g day-1 respectively. Juvenile birds probably vary their strategy according to time of season and prevailing conditions. Both adults and juveniles followed the Mediterranean Flyway, but juveniles displayed significantly more southerly and significantly more scattered migratory directions. © 2013 Copyright British Trust for Ornithology.
PubMed | Uppsala University, University of Konstanz, Ottenby Bird Observatory, Linnaeus University and Kristianstad University College
Type: Journal Article | Journal: PloS one | Year: 2014
The mallard (Anas platyrhynchos) is a focal species in game management, epidemiology and ornithology, but comparably little research has focused on the ecology of the migration seasons. We studied habitat use, time-budgets, home-range sizes, habitat selection, and movements based on spatial data collected with GPS devices attached to wild mallards trapped at an autumn stopover site in the Northwest European flyway. Sixteen individuals (13 males, 3 females) were followed for 15-38 days in October to December 2010. Forty-nine percent (SD=8.4%) of the ducks total time, and 85% of the day-time (SD=28.3%), was spent at sheltered reefs and bays on the coast. Two ducks used ponds, rather than coast, as day-roosts instead. Mallards spent most of the night (76% of total time, SD=15.8%) on wetlands, mainly on alvar steppe, or in various flooded areas (e.g. coastal meadows). Crop fields with maize were also selectively utilized. Movements between roosting and foraging areas mainly took place at dawn and dusk, and the home-ranges observed in our study are among the largest ever documented for mallards (mean =6,859 ha; SD=5,872 ha). This study provides insights into relatively unknown aspects of mallard ecology. The fact that autumn-staging migratory mallards have a well-developed diel activity pattern tightly linked to the use of specific habitats has implications for wetland management, hunting and conservation, as well as for the epidemiology of diseases shared between wildlife and domestic animals.