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Tuesday, 5 August 2014

Ardea: July 2014; Volume 102, Issue 1: Table of Contents and Abstracts

Published by: Netherlands Ornithologists' Union


July 2014 : Volume 102, Issue 1 


Table of Contents


Creating Long-Term Value: Natural History is the Basis
Rob Bijlsma , Bart Kempenaers & Theunis Piersma
pg(s) 1–2


Ornithology from the Tree Tops
Rob G. Bijlsma
pg(s) 3–4


Diversity of Nuptial Plumages in Male Ruffs Philomachus pugnax 
Johan van Rhijn, Joop Jukema & Theunis Piersma
pg(s) 5–20

Nuptial ornament diversity was studied in 1814 individual male Ruffs that were caught in their spring staging areas in Friesland, The Netherlands. Ornaments (hereafter called plumages) comprised of a ruff, two head tufts and facial wattles. Individual feathers were found to be plain (white, black or one hue), or patterned with black and only one hue. Patterns of feathers varied modestly within males, and greatly between males. The colour of a male's ruff plus head tufts consisted of black and/or white and/or only one other hue. Ruff, head tufts and facial wattles differed In coloration and pattern between individuals. Using seven criteria we counted 801 different plumage variants. Nevertheless, except for wattle colour, characteristics did not combine at random. Some combinations of characteristics, such as a white ruff with white head tufts, occurred much more often than expected by chance. Other combinations, such as a white ruff with black head tufts, a black ruff with white head tufts, and a regular ruff pattern with an Irregular pattern, were rare. Mostly there was conformity between ruff and head tufts: they were identical or had reversed primary and secondary colours. Nuptial plumage characteristics were only weakly associated with body size. Some associations between nuptial plumage and the timing of moult were remarkable: only white males and males with a plain ruff pattern tended to have completed moult by the time of their capture In April. We discuss our findings, including the extreme diversity of nuptial plumages among individuals, In the light of development, genetics and function.

Environmental Drivers of an Urban Hadeda Ibis Population
Gregory Duncan Duckworth & Res Altwegg
pg(s) 21–29

Weather and habitat-use are key factors that influence the survival of a species. A central goal in conservation biology is to gain a mechanistic understanding of how these quantities limit a species' range. We examined how weather, season and geographic location influenced the demographic rates of an urban population of Hadeda Ibises Bostrychia hagedash on the leading edge of its expanding range in the Western Cape of South Africa. The Hadeda Ibis has increased its South African range 2.5 times within the last 50 years and is now a common urban resident throughout most of the country. Using capture—mark—recapture and generalized linear models, we build upon previous demographic analyses of this species. Our results show no significant influence of weather on demographic rates. Rainfall triggered the onset of the main breeding season (although breeding pairs were found at any time throughout the year), and Hadeda Ibises adjusted their breeding phenology according to the rainfall season of the areas into which they expanded. There was no evidence of spatial correlation within the study area. Hadedas have quickly adapted well to urban areas outside of their original range. Because weather had little effect on Hadeda demographics we suggest that urban areas may potentially buffer unfavourable effects of weather on Hadeda survival and are an important factor in the successful range expansion. This finding is consistent with the explanations of range expansions of other ibis species throughout the world.

Geographical Patterns in Primary Moult and Body Mass of Greenshank Tringa nebularia in Southern Africa
Magdalena Remisiewicz, Anthony J. Tree, Les G. Underhill & Jarosław K. Nowakowski
pg(s) 31–46

Greenshanks Tringa nebularia show various patterns of primary moult in the northern hemisphere, but farther south moult patterns are known only fragmentarily. We Identified geographical patterns in primary moult and pre-migratory fattening of Greenshanks on their southernmost African non-breeding grounds. We compared primary moult (using Underhill-Zucchini models) and body mass at a population level based on 356 Greenshanks caught in 1968–1998 at inland wetlands in Zimbabwe, and on the east and west coasts of South Africa. About 20% of immatures replaced one to five outer primaries in December—May, a rare pattern in the north. Sub-adults moulted all primaries on average 40 days earlier than adults, yet at the same rate. Adults started primary moult on average 16–19 days earlier in Zimbabwe and at the east coast than at the west coast (7, 4, 23 September, resp.). These dates correspond with the Greenshanks' broad-front arrival in Zimbabwe and the east coast, and their later arrival at the west coast. Moult took 10–17 days longer on average in Zimbabwe and at the east coast than at the west coast (122, 115, 105 days, resp.), thus the end of moult coincided within six days (31 December—6 January). Pre-migratory fattening began about 13–19 January across all regions. The mean departure fat loads of adults were 76 g In Zimbabwe, 116 g at the west coast and 125 g at the east coast. The heaviest adults from all three regions could reach the Nile Valley or the Red Sea coast in one non-stop flight. We suggest that Greenshanks at inland wetlands of Zimbabwe benefit from a shorter return migration distance and lower competition than at the coasts, and abundant food during the entire austral summer In favourable years, but can move on to the coasts if conditions deteriorate.

Conspecific Egg Removal Behaviour in Eurasian Tree Sparrow Passer montanus
Satoe Kasahara, Yasuhiro Yamaguchi, Osamu K. Mikami & Keisuke Ueda
pg(s) 47–52

In farmland in central Honshu, Japan, conspecific infanticide was recorded in five out of 68 breeding attempts of Eurasian Tree Sparrow Passer montanus in 2011 and 2012 including one suspected case. The number of eggs lost by infanticide accounted for 20% in 2011 and for 24.1% in 2012 of the total egg and nestling losses. In three out of five cases, subsequent nesting took place in the nest box where infanticide had caused the loss of a clutch, twice by the perpetrator and once by unknown breeders. In this population, infanticide was a major cause of breeding failure.

Pedestrian Density Influences Flight Distances of Urban Birds 
Peter Mikula
pg(s) 53–60

Birds inhabiting urban areas have to cope with novel conditions. Unlike natural habitats, birds in urban environments are exposed to an increased human presence which often induces stress. Urban birds with reduced sensitivity to human disturbance can obtain benefits such as longer foraging time or decreased energy costs for escape. Here, I tested the hypothesis that the decrease in flight initiation distance (FID) to a potential predator (an approaching human) reflects adaptation to the level of disturbance expressed as pedestrian density. Moreover, I studied the Influence of habitat type and species on observed FIDs. I analysed 2117 flight distances (20 species of European birds) located in ten localities in Prague. I found that species and pedestrian density play a more important role in determining FIDs than the type of habitat. Moreover, urban populations exposed to increased pedestrian density had consistently shorter flight distances. This study provides empirical documentation of changes in anti-predator behaviour, which strongly correlate with the pedestrian density gradient. It could support the idea that the establishment of FID can be highly plastic process depending on local conditions, as it is highly affected by a bird's individuality and its ability to adapt to the local level of disturbance by learning.

Habitat Selection of Brood-Rearing Northern Wheatears Oenanthe oenanthe and Their Invertebrate Prey
H. Herman van Oosten, A.B. van den Burg, R. Versluijs & H. Siepel
pg(s) 61–69

Birds consider both variation in prey abundance and accessibility in their decision of where to forage. Acidification and nitrogen deposition affect both prey abundance and accessibility by stimulating growth of nitrophilic grasses at the expense of forbs. Management practises such as mowing or grazing primarily affect vegetation structure which also influences the abundance and accessibility of invertebrates. Hence, for effective management and conservation purposes It is paramount to understand the relationships between vegetation structure, densities of preferred prey and habitat-use of birds. In this study we explore such relationships for the nationally endangered Northern Wheatear Oenanthe oenanthe in dune grasslands along the Dutch coast. Our findings support the hypothesis that forager mobility and food accessibility are of greater importance during patch selection than food abundance per se in ground foraging birds. The abundance of all potential prey and three of the four most important actual prey groups was highest in tall grass, but Northern Wheatears foraged preferentially in short grass. Clearly, encroachment by tall grass will diminish habitat suitability for Northern Wheatears due to lowered prey accessibility. We propose that a mixture of short and tall vegetation and landscape management allows for dispersal of arthropods between different (micro)habitats. We provide densities of the important prey in a coastal area where Northern Wheatears still successfully breed. This enables site-managers to efficiently investigate presence and abundance of important prey In seemingly suitable areas but where Northern Wheatears do not breed. Eventually we may be able to discern whether food shortage poses a bottleneck for Northern Wheatears in these uninhabited areas.

Intraspecific Intrusion at Bald Eagle Nests
Courtney Turrin & Bryan D. Watts
pg(s) 71–78

Competition for nesting territory has been shown to act as a density-dependent feedback mechanism influencing population growth rate. However, little is known about the nature of territorial interactions between established breeders and floaters. We examined territorial intrusion rates and associated behaviours at active Bald Eagle Haliaeetus leucocephalus nests in the lower Chesapeake Bay in 2012 and 2013. The average intrusion rate experienced at study nests during the reproductive period was 0.28 ± 0.32 intrusions/h. Variance in intrusion rate was high and there was no apparent predictive pattern to these events. Juvenile intrusions occurred closer to the nest than adult intrusions, and breeders showed higher response rates toward adults, with 78% of adult intruders eliciting a response compared to 47% of juveniles. Breeding adults responded to intruders significantly more often and more aggressively when in the presence of their mate. Further research is necessary to broadly describe the relationship between intrusion frequency and the frequency of nest failure.

Rain may have more Influence than Temperature on Nest Abandonment in the Great Tit Parus major
Dejan Bordjan & Davorin Tome
pg(s) 79–86

The main aim of this study was to investigate which weather parameter has greater influence on nest abandonment in the Great Tit Parus major, temperature or rain, and to determine during which breeding period nests are the most susceptible to abandonment. Breeding parameters of a nest-box population in Slovenia were monitored over a three year period at two locations in three altitude belts. Weather parameters were measured daily. From 160 first nesting attempts, 35 nests were abandoned. The majority of abandoned nests were found during the incubation period, followed by the first half of the nestling period. The amount of rainfall was more important than temperature in explaining variation in nest abandonment.

Predators and Predation Rates of Skylark Alauda arvensis and Woodlark Lullula arborea Nests in a Semi-Natural Area in the Netherlands 
Libor Praus, Arne Hegemann, B. Irene Tieleman & Karel Weidinger
pg(s) 87–94

Predation is a major cause of breeding failure in bird species with open nests. Although many studies have investigated nest predation rates, direct identification of nest predators is sporadic, especially in (semi-)natural habitats. We quantified nest success and identified nest predators in a population of Skylarks Alauda arvensis and Woodlarks Lullula arborea breeding in a protected semi-natural area dominated by heathland and different succession states of grassland on nutrient-poor soil in The Netherlands. We monitored 54 nests by means of continuous video surveillance to determine survival times and predators, and monitored another 44 nests without a camera. Fates of the 58 (40) Skylark (Woodlark) nests were: fledging 41 (27), depredation 13 (12), egg desertion 1 (0) and nestling death 3 (1). The overall nest success of all monitored nests (58 (40), Mayfield estimate) was 33% (22%; all mortality factors considered) or 43% (25%; only depredation). Predators of Skylark nests were Red Fox Vulpes vulpes (5), Carrion Crow Corvus corone (1) and European Adder Vipera berus (1). Woodlark nests were depredated by Carrion Crow (2), Eurasian Jay Garrulus glandarius (1) and Red Fox (1). Results suggest that the main nest predators might differ between the two co-occurring lark species; Skylark nests located in more open sites were preyed upon mainly by Red Fox, while the main predators of Woodlark nests, located generally closer to trees, are corvids.

Colour Morphs in the Collared Pygmy Owl Glaucidium brodiei are Age-Related, not a Polymorphism 
Wen-Loung Lin, Si-Min Lin & Hui-Yun Tseng
pg(s) 95–99

Colour morph variation is widely observed in owls and several studies have described differences In life history traits among the morphs. Traditionally, Glaucidium owls are described as having two colour morphs, rufous and grey, which are supposedly independent of age or sex. During 2010–2012, nest boxes were set up in order to study the basic life history of Collared Pygmy Owls Glaucidium brodiei. We banded the population and followed some of the fledglings for nearly two years. Our results — in combination with data from museum specimens — clearly show that the colour morph In Collared Pygmy Owls is age-dependent, changing from the original fledgling plumage (2–3 months after hatching) to the rufous morph (4–7 months after hatching), and finally to the definitive grey plumage. Our results reject the long-standing polymorphism hypothesis for the pygmy owl. We conclude that the age of the birds should be considered before a colour polymorphism can be confirmed, especially in secretive nocturnal species. The case of within-species polymorphism might be overstated in Strigiformes.


Deadly Gastroliths: Eurasian Siskins Carduelis spinus Poisoned by Road Salt Grains
Till Töpfer, Libor Mazánek & Stanislav Bureš
pg(s) 101–104

We describe a case of winter mass mortality of Eurasian Siskins Carduelis spinus caused by large road salt grains that birds apparently had mistaken for potential gizzard stones (gastroliths). Clinical evidence revealed acute salt intoxication as the cause of death. We recommend using only small-sized salt grains (<2 mm) for de-icing roads in order to save wintering birdlife from a potentially hazardous substance.

A Case of a Three Species Mixed Brood after Two Interspecific Nest Takeovers
Jelmer M. Samplonius & Christiaan Both
pg(s) 105–107

Mixed interspecific broods in hole nesting passerines occasionally occur as a by-product of competitive interactions for nest sites. Here, we report a rare case where such interactions led to a three species brood of Pied Flycatcher Ficedula hypoleuca, Blue Tit Cyanistes caeruleus and Great Tit Parus major nestlings that was successfully raised by a Great Tit pair. This occurred in an environment of relatively high temporal overlap in interspecific breeding. We suggest that such overlap may intensify interspecific competition between resident and migrant passerines that rely on similar resources.

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