Ingvar Byrkjedal

Antipredator behavior and breeding success in greater Golden-Plover and Eurasian Dotterel

Breeding success and antipredator behavior of Greater Golden-Plovers (Pluvialis apricaria) and Eurasian Dotterels (Charadrius morinellus) were studied in Norway over seven summers in an area 1,200 to 1,350 m altitude. Behavior was recorded in a standardized manner on nest inspections, on approaching parent birds with chicks, and by observing reactions to overflying predators on scheduled observation bouts. Red foxes (Vulpes v&es), Common Ravens (Corvus corax), and Mew Gulls (Larus canus) were the most important nest and chick predators in the area. Nest predation was calculated from exposure time. During incubation both species either sneaked away from the nest when approached by a human (golden-plovers at a much larger distance than dotterels) or sat tightly and flushed at a short distance giving distraction display. “Sneaking” had a positive effect on nest survival, and ground distraction displays had a better effect on nest survival than flight distraction displays. After hatching, golden-plover parents exposed themselves to an approaching human at several hundred meters distance by loud alarm calls and by encountering the intruder, whereas dotterels kept unobtrusive until approached to about 40 m, and upon further approach finally gave distraction displays on the ground. Avian predators at a longer distance (~300 m) from nest or chicks at most aroused alertness, while at close quarters (~50 m) they induced golden-plovers to squat flat, while dotterels exposed themselves by “tail-flagging.” Nest loss was greater for golden-plovers (78%) than for dotterels (47%), while chick loss was greater for dotterels (65%) than for golden-plovers (28%). The difference in nesting success and antipredator behaviors is discussed in terms of greater detectability in golden-plovers than dotterels, and of biparental (golden-plover) versus uniparental (dotterel) care.

The fauna of hydrothermal vents on the Mohn Ridge (North Atlantic)

Abstract The macrofauna of the newly discovered hydrothermal vent field on the Mohn Ridge at 71°N was investigated. Samples were collected during the cruise BIODEEP 2006 using the ROV ‘Bathysaurus’. A total of 180 species-level taxa were identified. The region contains very few vent-endemic species, but some species of Porifera, Crustacea and Mollusca may be vent-associated. Dense aggregations of motile non-vent species such as Heliometra glacialis and Gorgonocephalus eucnemis surrounded the vent area, but the area in general only held small numbers of sedentary animals. Calcareous sponges comprised an unusually high portion of the sponge species found and they constitute one of the first pioneers among the sessile invertebrates settling on these vents. Possible explanations for the structure of the fauna in the region are discussed.

Distribution of demersal fish in the south‐western Barents Sea

The composition of the demersal fish fauna of the Barents Sea, and the ranges of most of the fish species, have been relatively poorly known. From 257 bottom trawl hauls distributed in a uniform grid pattern over the southwestern part of the Barents Sea in summer 2000, all fish were identified. The sampled area included the Polar Front zone where warm Atlantic water meets cold (subzero) polar water. The material was used to map the distribution of the demersal fish species, and to analyse their distribution in relation to temperature, depth and salinity. Fifty-eight species were recorded. A fauna characterized by Gadidae and Scorpaenidae was found in the warmer part of the sea, whereas a cold-water fauna of mainly Cottidae, Zoarcidae and Stichaeidae was evident from the Polar Front zone and northwards. In logistic regression analyses temperature was the most important factor associated with the distribution of species (for 26 of the 27 species analysed), but associations with salinity (19 species) and depth (15 species) were also found. The mapping considerably revised the distribution in relation to previous knowledge for 37 species, and the new and more accurate range maps provided here may serve as baseline information for future monitoring of the fish fauna in the Barents Sea.

Mitogenomic sequences and evidence from unique gene rearrangements corroborate evolutionary relationships of myctophiformes (Neoteleostei)

BackgroundA skewed assemblage of two epi-, meso- and bathypelagic fish families makes up the order Myctophiformes – the blackchins Neoscopelidae and the lanternfishes Myctophidae. The six rare neoscopelids show few morphological specializations whereas the divergent myctophids have evolved into about 250 species, of which many show massive abundances and wide distributions. In fact, Myctophidae is by far the most abundant fish family in the world, with plausible estimates of more than half of the oceans combined fish biomass. Myctophids possess a unique communication system of species-specific photophore patterns and traditional intrafamilial classification has been established to reflect arrangements of photophores. Myctophids present the most diverse array of larval body forms found in fishes although this attribute has both corroborated and confounded phylogenetic hypotheses based on adult morphology. No molecular phylogeny is available for Myctophiformes, despite their importance within all ocean trophic cycles, open-ocean speciation and as an important part of neoteleost divergence. This study attempts to resolve major myctophiform phylogenies from both mitogenomic sequences and corroborating evidence in the form of unique mitochondrial gene order rearrangements.ResultsMitogenomic evidence from DNA sequences and unique gene orders are highly congruent concerning phylogenetic resolution on several myctophiform classification levels, corroborating evidence from osteology, larval ontogeny and photophore patterns, although the lack of larval morphological characters within the subfamily Lampanyctinae stands out. Neoscopelidae is resolved as the sister family to myctophids with Solivomer arenidens positioned as a sister taxon to the remaining neoscopelids. The enigmatic Notolychnus valdiviae is placed as a sister taxon to all other myctophids and exhibits an unusual second copy of the tRNA-Met gene – a gene order rearrangement reminiscent of that found in the tribe Diaphini although our analyses show it to be independently derived. Most tribes are resolved in accordance with adult morphology although Gonichthyini is found within a subclade of the tribe Myctophini consisting of ctenoid scaled species. Mitogenomic sequence data from this study recognize 10 reciprocally monophyletic lineages within Myctophidae, with five of these clades delimited from additional rearranged gene orders or intergenic non-coding sequences.ConclusionsMitogenomic results from DNA sequences and unique gene orders corroborate morphology in phylogeny reconstruction and provide a likely scenario for the phylogenetic history of Myctophiformes. The extent of gene order rearrangements found within the mitochondrial genomes of myctophids is unique for phylogenetic purposes.

Radiocesium ([sup 137]Cs) from the Chernobyl reactor in Eurasian woodcock and earthworms in Norway

To understand the ecological effects of the Chernobyl reactor accident, we investigated radiocesium ([sup 137]Cs) levels in Eurasian woodcock (Scolopax rusticola), earthworms (Lambricidae), litter (dead organic materials lying on the ground), humus (beneath litter 2 cm deep), and mineral soil samples (3-6 cm deep) from a heavily effected (20-60 kBq/m[sup 2][1 Bq = 1 nuclear fission/sec]) area in Norway. The highest concentrations measured in earthworms (1988 median = 142 Bq/Kg) and woodcock (1986 median = 730 Bq/kg) for human food (600 Bq/kg fresh mass) only were found in woodcock during 1986. Radiocesium concentrations decreased (P < 0.001) in earthworms (40%) and woodcock (95%) from 1986 to 1990. There was no reduction in total radiocesium in soil over the same period. The relatively high radiocesium concentrations in woodcock during 1986 and the decreasing radiocesium ratio in woodcock to earthworms during the first years following fallout could have been caused by woodcock ingesting abiotic radiocesium with earthworms. The decrease in radiocesium in woodcock and earthworms during the study (1986-90) probably resulted from decreasing bioavailability of radiocesium during the first years after fallout rather than by radiocesium disappearing from the ecosystem. 38 refs., 3 figs., 2 tabs.

Egg size in relation to sex of embryo, brood sex ratios and laying sequence in northern lapwings ( Vanellus vanellus )

Egg size in relation to sex of embryo, brood sex ratios and laying sequence in northern lapwings (Vanellus vanellus)

Sex and age biased mobility in Hawk Owls Surnia ulula

The distribution of sex and age classes of Hawk Owls in Norway outside the breeding season was analysed from 79 fresh birds and museum specimens. The tendency to move from the breeding range down to the lowlands was most pronounced in adult females, less so in juvenile males, and least in adult males and juvenile females. A combination of social dominance and competition for breeding territories may account for this distribution pattern.

Habitat use and resource overlap by breeding Golden Plovers and Dotterels (Pluvialis apricaria, Charadrius morinellus)

Golden Plovers and Dotterels breeding in sympatry fed and nested onCladonia heath, especially in the early part of the season. An increasing number of habitats were used as they became available, andSalix herbacea beds were used disproportionately frequently by post-breeding flocks of both species and off-duty (incubating) Golden Plover females, apparently due to good insect and arachnid availability late in the season. The species overlapped considerably in resource use and showed no signs of resource partitioning under circumstances where it could be expected from the competitive exclusion principle. Aggression from Golden Plovers towards Dotterels indicated some competitive interaction early in the season, when snow cover reduced the feeding grounds to 5–25 %. There was, however, no evidence for interspecific effects on breeding densities. It is concluded that competition between the two species is of little importance; their spacing patterns are probably usually governed by other factors than food. Gold- und Mornellregenpfeifer benutzten bei sympatrischen Vorkommen in S-Norwegen in hohem Maß flache Hügelketten mitCladonia sowohl als Nesthabitat als auch zur Nahrungs-suche, besonders zu Beginn der Brutsaison. Diese flachen Hügelketten waren arm an Invertebraten, doch reich anEmpetrum-Beeren, und bildeten fast das einzige zugängliche Habitat vor dem vollen Eintritt der Schneeschmelze. Später wurden mehrere Habitate besetzt. Flächen mitSalix herbacea wurden sowohl von Vögeln, die das Brutgeschäft beendet hatten (Trupps beider Arten), als auch von Weibchen des Goldregenpfeifers in der Brutzeit vorzugsweise aufgesucht. Wahrscheinlich hing dies mit dem Angebot an Insekten und Spinnen in der zweiten Hälfte der Brutzeit zusammen. Die Ressourcennutzung beider Arten war sehr ähnlich; Anzeichen für Ressourcenaufteilung gemäß dem Konkurrenz-Ausschlußprinzip wurden nicht gefunden. Aggression von Goldregenpfeifern gegen Mornellregenpfeifer am Anfang der Saison deutet auf Konkurrenz zu dieser Zeit hin, als nur 5–25 % der Fläche vom Schnee frei waren. Eine Auswirkung auf die Siedlungsdichte ließ sich nicht erkennen. Konkurrenz zwischen beiden Arten dürfte also nur einen geringen Einfluß auf die Dispersionsmuster haben, das wahrscheinlich von anderen Faktoren als der Nahrung bestimmt wird.

Seasonal variation in egg size in golden plover Pluvialis apricaraia and Dotterel Charadrius morinellus populations

In two Golden Plover populations in S. Norway (Jaeren: heather moor at 300-400 m elevation, and Hardangervidda: middle alpine zone at 1200-1300 m elevation) there was a negative correlation between egg volume and the date on which clutches were started. A Dotterel population in the study area on Hardangervidda did not show any trend in egg volume in relation to the start of egg-laying. On Jaeren more late than early Golden Plover clutches contained fewer than 4 eggs. On Hardangervidda no reduction of clutch size with season was found in either Golden Plover or Dotterel. In newly hatched Dotterel chicks both body weight and tarsus length were positively correlated with egg volume, while no such data were collected for Golden Plover. It is argued that, in waders, populations of single-brooded species should show a decrease in egg volume with season, whereas this should not apply to multi-brooded species.

Bestandsutvikling hos vipe, storspove og tjeld på Jæren i 15-årsperioden 1997-2011

Northern Lapwing Vanellus vanellus, Eurasian Curlew Numenius arquata, and Eurasian Oystercatcher Haematopus ostralegus were censused annually around 20 April, between 1997-2011, along a standardized route in Jæren, SW Norway. The area censused comprises 2972 ha, consisting of grassland, arable land, improved pasture, and heather moor. The area is intensively farmed, but has since long been a core area for breeding Lapwing and Curlew, and inland breeding of Oystercatchers has a history of several decades. Number of censused Lapwings along the route varied between years from 137 to 497, Curlews from 18 to 55 and Oystercatchers from 15 to 81. Linear regressions showed a statistically significant decline in Lapwings over the whole census period, while significant negative linear trends were found in numbers of Curlews and Oystercatchers over the 10 and 8-9 last years, respectively. The negative trend of the latter two species seems to have stopped in more recent years. Estimated from the regressions Lapwing numbers have declined by 44% over the census period, and by 53% when estimated from counts of the number of males. Since the trend is found in a core area of the species, this is a worrying situation for the Lapwing as a breeding bird in this region of Norway. The decline of Lapwing and Oystercatcher was more pronounced in cropland than in pasture habitats, indicating an effect from agricultural activities.