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Monday, 15 June 2015

Ardea, Netherlands Ornithologists' Union: June 2015, Volume 103, Issue 1 - Abstracts

Published by: Netherlands Ornithologists' Union

Table of Contents
June 2015 : Volume 103 Issue 1 


Ornithology from the Lakeshore 

Bart Kempenaers


Large-Scale Monitoring of Waders on Their Boreal and Arctic Breeding Grounds in Northern Europe 

Åke Lindström, Martin Green, Magne Husby, John Atle Kålås & Aleksi Lehikoinen

Large-scale and population-wide monitoring of waders on their boreal and arctic breeding grounds has hitherto been lacking, mainly because logistics are truly challenging in regions with few ornithologists, vast areas and few roads. In Norway, Sweden and Finland (here ‘Fennoscandia’) there are now national monitoring schemes in place, aimed at tracking all bird species, which allows trends to be estimated for northern wader populations. We present joint Fennoscandian population trends for 24 wader species, covering the period 2002–2013 (in some cases somewhat shorter time periods). The data stem from 1263 routes in Norway, Finland, and the northern two thirds of Sweden, all situated north of 58°N. This area of one million km2 largely coincides with the boreal and arctic parts of Fennoscandia. The trends found are rather evenly distributed between strong increases and strong declines. Trends do not differ between short- and long-distance migrants, nor do they vary in relation to breeding latitude. Ringed Plover Charadrius hiaticula, Wood Sandpiper Tringa glareola, Green Sandpiper T. ochropus and Common Redshank T. totanus had significant positive trends, whereas Common Snipe Gallinago gallinago, Ruff Philomachus pugnax and Spotted Redshank Tringa erythropus were declining significantly in numbers. Trends could be calculated even for relatively uncommon breeding birds such as Temminck's Stint Calidris temminckii, Eurasian Dotterel Charadrius morinellus, Broad-billed Sandpiper Limicola falcinellus, Jack Snipe Lymnocryptes minimus and Red-necked Phalarope Phalaropus lobatus, although these trends build on few routes and individuals, and thus have low precision. The monitoring schemes in Norway and Finland are expected to increase in coverage in the coming years, with up to a total of 1555 northern routes being tracked when the schemes are fully developed. This should enable still more robust trend estimates for northern waders on their Fennoscandian breeding grounds to be calculated in the future.

Food Availability for Meadow Bird Families in Grass Field Margins 

J.M.R. (Hanneke) Wiggers, Jasper van Ruijven, André P. Schaffers, Frank Berendse & Geert R. de Snoo

Agricultural intensification in grasslands has led to the decline of meadow bird populations in The Netherlands in the last 60 years. Habitat for meadow bird chicks has declined in quality and quantity, thereby reducing food availability. Agri-environment schemes (AES) to halt the decline in meadow bird numbers have thus far been insufficient. These AES are on the level of entire fields, but recent research suggests that margins of fields may be more suitable chick habitat than centres of fields. Therefore, it could be productive to specifically target grass field margins as part of meadow bird AES. Our study examined the differences in food availability for meadow bird families in different portions of a grass field. Invertebrates were sampled in different locations on the field and results were compared to known dietary preferences of four species of meadow bird chicks. We show strong differences in food availability within fields, depending on meadow bird species. The preferred prey species of chicks of Black-tailed Godwit Limosa limosa and Redshank Tringa totanus predominantly occurred in field margins, whereas those of Oystercatcher Haematopus ostralegus chicks were found mostly in the main part of the field. The prey species of Northern Lapwing Vanellus vanellus chicks showed no clear pattern within fields. We conclude that food availability within a field differs spatially between meadow bird species. Particularly for Black-tailed Godwit and Redshank, grass field margins constitute an important part of the field. Therefore, specific management to further enhance food availability in these margins may constitute an important addition to the existing mosaic approach.

Avoiding Competition? Site Use, Diet and Foraging Behaviours in Two Similarly Sized Geese Wintering in China

Meijuan Zhao, Lei Cao, Marcel Klaassen, Yong Zhang & Anthony D. Fox

Competition may occur when two species with similar feeding ecologies exploit the same limited resources in time and space. In recent years, the Eastern Tundra Bean Goose Anser fabalis serrirostris and Greater White-fronted Goose Anser albifrons frontalis have increased in wintering numbers at Shengjin Lake, China. To examine the potential for coexistence and possible avoidance strategies, we studied (1) their habitat use, (2) foraging behaviours and (3) diets of birds foraging in mixed- and single-species flocks. Both species extensively exploited sedge meadows, where they showed considerable overlap in spatial distribution and diet. The percentage feeding time and diet of both species were unaffected by the presence of the other. Greater White-fronted Geese appeared diurnal sedge meadow specialists, almost never feeding in other habitats. Eastern Tundra Bean Geese were less selective, exploiting other habitats, which they increasingly exploited at night in mid-winter. The use of alternative habitats and night feeding may have avoided interspecific competition. While the specialised feeding ecology of Greater White-fronted Geese may make them particularly vulnerable to loss of sedge meadow habitat, Eastern Tundra Bean Geese may be able to adjust because of their use of alternative habitats and a less restricted diet.

Selective Forces Responsible for Transition to Nesting on Electricity Poles in the White Stork Ciconia ciconia 

Tomasz Janiszewski, Piotr Minias & Zbigniew Wojciechowski

The process of transition from nesting on trees to electricity poles has been observed over the last decades in many European populations of the White Stork Ciconia ciconia, but the direct mechanisms behind this process have not been explicitly identified. The aim of this study was to identify selective forces responsible for transition to nesting on electricity poles using long-term data (1994–2011) collected for the central Polish population of c. 190 breeding pairs. We hypothesized that transition to nesting on electricity poles could be explained by two non-exclusive mechanisms. Firstly, the process could be driven by insufficient availability of traditional nesting sites in the vicinity of favourable foraging grounds. Secondly, nesting on electricity poles could be directly associated with fitness benefits resulting from different nest structure and microclimate. We found that the process of transition had started and proceeded at the highest rate in the good- and medium-quality areas of river valleys, where most intense competition for nesting territories and highest stork densities were recorded. By contrast, we found little support for direct fitness benefits associated with nesting on electricity poles. In fact, reproductive success (number of fledglings per pair) of storks nesting on poles was lower in comparison to those nesting on trees, but this relationship prevailed only in the areas of poor quality (dry agricultural landscape). The results strongly suggest that the process of transition to nesting on electricity poles in the White Stork is not facilitated by direct reproductive benefits, but could be driven by decreasing availability of natural nesting sites in the attractive breeding areas.

Factors Driving Variation in Biparental Incubation Behaviour in the Reed Warbler Acrocephalus scirpaceus

Ewelina Klimczuk, Lucyna Halupka, Beata Czyż, Marta Borowiec, Jacek J. Nowakowski & Hanna Sztwiertnia

Biparental incubation is a common pattern of parental care in birds. Within species with biparental incubation, the contribution of each sex can vary widely. Many studies have addressed the factors that influence variation in female incubation behaviour, but the underlying causes of within-species variation in male incubation behaviour remain poorly understood. In this paper we analyse incubation behaviour in the Reed Warbler, a small, predominantly socially monogamous passerine nesting in reed beds. We examined the impact of time of day, weather conditions (ambient temperature, wind speed, rainfall) and progress of the breeding season on male and female incubation behaviour in 81 pairs of Reed Warbler breeding in the Barycz Valley (SW Poland). We found that females had on average higher nest attentiveness (total time spent incubating per hour) than their partners (47% vs. 29%) but mean incubation bout length (a single, uninterrupted stay at the nest) did not differ significantly between the sexes (9 min vs. 7 min). The two parents responded differently to changing environmental parameters. Female nest attentiveness was unaffected by date, time of the day, advancement of incubation and weather conditions, while males spent more time on the nest at higher wind speeds and lower temperatures. In contrast, male incubation bout length was not affected by these factors, whereas female bout length increased throughout the breeding season and was longer at lower temperatures. Incubation recesses (periods where both parents were off the nest) were longer during favourable weather conditions (at high temperatures and low wind), probably because cooling of the eggs takes much longer under such conditions and parents can spend more time foraging. A comparison of our results with those from other populations revealed important betweenpopulation and sex-specific differences in nest attentiveness expressed as the percentage of male/female time spent on the nest. We suggest that betweenpopulation variation may result from differences in habitat quality and/or food resources affecting the necessity of male contribution to parental care, variation in breeding synchrony and densities influencing male engagement in extra-pair copulations, differences in predation levels, or methodological differences.

Factors Affecting Post-Breeding Moult in the Savi's Warbler Locustella luscinioides in Northern Poland

Izabela Kulaszewicz & Dariusz Jakubas

A majority of Eurasian short-distance migrants moult after breeding and before autumn migration, while most long-distance migrants perform a winter moult in the tropics after autumn migration. Another strategy among long-distance migrants is a partial moult on the breeding grounds, suspended moult and then completion of moult on the wintering grounds. The Savi's Warbler Locustella luscinioides is a small passerine adopting such a ‘suspended moulting’ strategy. Here, we investigate the sequence and extent of the post-breeding moult in Savi's Warblers breeding in and migrating through northern Poland in relation to sex, body mass and date. We analysed 65 molecularly sexed adult Savi's Warblers (32 females and 33 males) caught during autumn migration in 2010–2011. Adult Savi's Warblers from the studied populations were found to suspend moult. Exchange of wing feathers started at the third primary (P3) and progressed in both directions. The onset of secondary moult began with S1 and occurred when P6 was shed. Tail moult occurred almost simultaneously with the secondaries. We did not find any significant differences between the sexes in time and extent of moult. Lack of sex differences in the time of moulting suggests comparable post-breeding condition (fat load, body mass) of females and males. In contrast to the present study, adults caught in Western Europe started post-breeding moult from P5, which may be explained by different populations migrating through northern Poland and Western Europe.

Laying Date is a Plastic and Repeatable Trait in a Population of Blue Tits Cyanistes caeruleus

Jack B. Thorley & Alex M. Lord

Temperature can have a profound influence on the optimal laying date of insectivorous passerines by affecting the timing of peaks in spring food abundance. If individuals do not synchronise their reproduction with respect to this food peak, it can have detrimental impacts on their reproductive success relative to well-matched breeders. In a population of Blue Tits studied for over a decade, we find that large between-year variation in the onset of laying is tightly coupled to pre-breeding spring temperatures, and that this population-level advancement in laying date in warmer springs can be completely accounted for by individual plasticity. Notwithstanding substantial plasticity within individuals across years, laying date is highly repeatable, with certain individuals consistently early or late. The substantial repeatability appears underlain by heritable variation for relative laying date (h2 = 0.30 +- 0.18 (SE), although this estimate has large standard error and is not significant. This makes assessment of the potential for evolutionary change in laying date problematic, despite observing strong directional selection favouring early-laying individuals. We found that part of the between individual variation in laying date was explained by the quality of the breeding territory and the age of the breeding female. Ornithologists have long sought to quantify variation in avian life histories, with particularly sophisticated experimental approaches and analyses applied to hole-nesting passerines. Nevertheless, there is still great value in presenting descriptions of long-term trends in life history traits, as has been done for laying date in this paper. Characterising such traits provide a useful baseline that is prescient in the face of a changing climate, which may decouple trophic interactions and reveal heterogeneous responses across populations. It also reinforces the value of replicating results and experiments in a field that is increasingly driven by novelty.

The Effect of Fire on the Habitat Use of the Black-Eared Miner Manorina melanotis

Thomas Raap, Griet Van Schoote, Marjolein van Dieren, Chris Hedger, Henry Kuipers & Martijn Weterings

In 2006, a widespread fire in the Bookmark Biosphere Reserve, South Australia, consumed over one-third of the old growth mallee considered to be the prime habitat of the endangered Black-eared Miner Manorina melanotis. Since 2008, the species has been observed foraging and breeding in the fire-altered area. To verify whether food resources can explain the Black-eared Miners' presence in habitat consisting of early seral stages, we examined if a link could be found between the foraging behaviour of the Black-eared Miner and its invertebrate food resources.

Foraging behaviour of Black-eared Miners was sampled opportunistically using focal observations. All potential invertebrate food resources were sampled using micro-pitfalls, malaise traps, beating trays, sweep nets and active searches. Black-eared Miners devoted significantly more time to foraging in long unburned (hereafter referred to as unburned) rather than in recently burned habitat. No differences in invertebrate abundance, species richness or diversity were found between burned and unburned habitats. However, differences in community composition between habitats were found. Lerp, which is a sugary protective covering of particular insect larvae, is an important food source for the Black-eared Miners, and was found more in the unburned natural habitat.

We found that Black-eared miners may be more adaptable than previously thought when it comes to utilization of burned habitat. Still, this study reaffirms the importance of unburned habitat for Black-eared Miners.


Selection of Nest Site and Nesting Material in the Eurasian Nuthatch Sitta europaea

Alejandro Cantarero, Jimena López-Arrabé & Juan Moreno

The selection of nest sites and nesting material may have important implications for avian reproductive behaviour and performance. Nest construction may involve costs arising from transporting material that may be reduced considerably if nest materials are located close to the nest site. Eurasian Nuthatch Sitta europaea nests in our nest box study area are mainly composed of pine bark flakes or alternatively of strips of bark of the widespread shrub Cistus laurifolius, with variable amounts of mud being used for plastering the entrance. Several small streams run through the area — an oak Quercus pyrenaica forest with a few scattered pines Pinus sylvestris. Here we show that Nuthatches collected pine bark only when nest sites were situated close to pines, used more mud when breeding close to streams and selected nest sites closer to streams than a sympatric species not using mud, the Pied Flycatcher Ficedula hypoleuca. Nuthatches used pine bark only when there was a pine tree less than 100 m away from the nest box and selected Cistus bark when transport distance was greater. We suggest that the selection of nest sites and nest materials in this species may be constrained by the costs of transporting nest material.

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