Sparrowhawk Accipiter nisus presence and winter bird abundance

The decline and subsequent re-colonisation of the Sparrowhawk Accipiter nisus in the UK has allowed an examination of its potential impacts on passerine abundance through analysis of long-term garden bird monitoring data. Weekly counts in gardens in winter have been collected annually since the early 1970s, a period when Sparrowhawks were initially rare but recolonised to a point in the 1990s when they were recorded in the majority of gardens. Change in bird count from year-to-year for 10 common prey species from up to 483 survey sites were analysed in relation to Sparrowhawk re-colonisation, the number of feeding units per site (e.g. bird tables, hanging bird feeders) and, for a subset of the data, minimum temperature. Year-to-year change increased with Sparrowhawk re-colonisation in Great Tit Parus major, Blue Tit Cyanistes caeruleus and Collared Dove Stretopelia decaocto, but decreased in Starling Sturnus vulgaris, Chaffinch Fringilla coelebs and Greenfinch Carduelis chloris. Positive associations may suggest a behavioural response to predators, or an attraction of predators to increased prey caused by confounding effects of improvement in site quality. The significant negative effects detected suggest that there is a temporal matching between increased predation pressure and decreases in bird abundance for certain species. However, there was no strong evidence that Sparrowhawk re-colonisation was linked to long-term declines in population size.

Consistency of passerine embryo development and the use of embryonic staging in studies of hatching failure

Hatching failure is widespread in birds, and is usually the result of embryo death rather than infertility. Embryo death can result from both intrinsic and extrinsic factors, some of which may vary across the developmental period. Determining the point at which an embryo died during development may therefore help us to understand the underlying cause of death. Here we describe simple criteria that can be used by field ornithologists to establish the developmental stage of dead embryos found in unhatched passerine eggs, and explain how this can be used to estimate the date of embryo death. We compared the pattern of embryo development over the incubation period for three species, the Zebra Finch Taeniopygia guttata, Blue Tit Cyanistes caeruleus and Great Tit Parus major. We also compared rates of Zebra Finch embryo development under artificial and standard (parental) incubation. Embryo development rates were remarkably similar across the three species and between Zebra Finch embryos under artificial and natural incubation conditions. We therefore suggest that the pattern of embryo development in the Zebra Finch may provide a model for other small passerines with similar incubation periods, but acknowledge that further interspecific comparisons are required before this model is considered more widely applicable. By estimating embryo death dates using our approach, ornithologists will be able to determine temporal patterns of embryo mortality in relation to extrinsic environmental conditions. This approach may shed light on how extrinsic factors such as climate and parental behaviour influence embryo survival in wild birds.     

Habitat and diet variability of two coexisting tit species in central European forests

Capsule: Blue Tits and Great Tits occupied different habitats within forests in Central Europe but their nestlings shared a similar diet.

Aims: To quantify the differences in offspring diet and territory habitat between Great Tits Parus major and Eurasian Blue Tits Cyanistes caeruleus in two European forests, and to test whether the ecological niches of the two species overlap.

Methods: Research was conducted on Great Tits and Eurasian Blue Tits, breeding in nest boxes in two forests near Kraków, Poland, during years: 2009, 2011 and 2012. Nine days after hatching, food items were collected from offspring using neck-collars. Habitat parameters surrounding each nest box were quantified.

Results: Great Tit territories were in old Oak-Hornbeam forest, whereas Blue Tits often nested in mixed forest. There were no significant differences between the two bird species in the variation in their caterpillar diets for which both species were highly variable. Great Tits collected more caterpillars of Noctuidae per nest than did Blue Tits in 2009 and 2011 in Niepo?omice Forest; Blue Tits collected more Tortricidae in 2011 and more spiders every year. In Krzyszkowice Forest in 2012, tits fed their nestlings in different periods and did not differ in the proportion of caterpillars. Habitat affected diet differently in each species.

Conclusion: Although Great Tits and Blue Tits occupied different territories in each forest and year of research, the diets of both species’ nestlings contained similar species of invertebrates. The overlaps of the birds’ environmental needs are specific at a local scale.     

Annual and seasonal trends in the use of garden feeders by birds in winter

Provision of bird food in gardens is a common activity that may provide an alternative food source to birds in winter. Long-term survey data recording the weekly presence of all bird species using garden feeders in the winter were analysed to see if there was any evidence of trends in feeder use between 1970 and 2000 and whether these trends were correlated with breeding bird population trends. Of 41 species analysed, 21 showed significant increases in occurrence at garden feeders between 1970 and 2000. Many of these increases were evident only in the last 10 years. Several species showed significant positive correlations between trends in winter garden use and trends in relative population size in the previous breeding season. This was especially the case for species with population change (either increase or decrease) of the greatest magnitude. There was no evidence that seasonal shifts in garden feeder use were associated with population change in any species. Temperature was an important predictor of garden use but could not explain the year-to-year trends. However, as the number of feeding stations had increased over time the response of birds to the greater food availability in gardens may have been responsible for the widespread increases in occurrence of several species.     

Parid foraging choices in urban habitat and their consequences for fitness

Urban environments are habitat mosaics, often with an abundance of exotic flora, and represent complex problems for foraging arboreal birds. In this study, we used compositional analysis to assess how Blue Tits Cyanistes caeruleus and Great Tits Parus major use heterogeneous urban habitat, with the aim of establishing whether breeding birds were selective in the habitat they used when foraging and how they responded to non‐native trees and shrubs. We also assessed whether they showed foraging preferences for certain plant taxa, such as oak Quercus, that are important to their breeding performance in native woodland. Additionally, we used mixed models to assess the impact of these different habitat types on breeding success (expressed as mean nestling mass). Blue Tits foraged significantly more in native than non‐native deciduous trees during incubation and when feeding fledglings, and significantly more in deciduous than evergreen plants throughout the breeding season. Great Tits used deciduous trees more than expected by chance when feeding nestlings, and a positive relationship was found between the availability of deciduous trees and mean nestling mass. Overall, the breeding performance of both species was poor and highly variable. Positive relationships were found between mean nestling mass and the abundance of Quercus for Great Tits, but not for Blue Tits. Our study shows the importance of native vegetation in the complex habitat matrix found in urban environments. The capacity of some, but not all, species to locate and benefit from isolated patches of native trees suggests that species vary in their response to urbanization and this has implications for urban ecosystem function.     

Food diversity and niche-overlap of sympatric tits (Great Tit,Parus major,Blue Tit,Cyanistes caeruleus and Coal Tit Periparus ater) in the Hyrcanian Plain forests

Abstract

This study was carried out between early summer 1998 and late summer 1999 in the Hyrcanian Plain forests, the southern Caspian Sea woodlands. In total, the gizzard contents of 241 specimens of the Great Tit (Parus major Linnaeus, 1758), Blue Tit (Cyanistes caeruleus Linnaeus, 1758), and Coal Tit (Periparus ater (Linnaeus, 1758)) were collected so that the percentages of grit, plants and animal materials could be estimated and the plant and invertebrate species consumed identified. The data were tested by a series of Mann-Whitney U, ANOVA and Kruskal-Wallis tests. To survey niche overlap of food materials between species and season, the symmetrical overlap index developed by Pianka (1973) was used. The most important invertebrates (maximum of percentage per season) in the diet of P. major were Coleoptera (36.5%) and Lepidoptera (33.6%), for C. caeruleus Coleoptera (34.5%) and Araneae (31.2%), and for Pe. ater Coleoptera (38.2%) and Araneae (35.6%). The most important plants consumed by P. major were Sorghum halepense (68.7%) and Ficus carica (65.6%), by C. caeruleus were F. carica (67.5%) and Alnus glutinosa (39.4%), and by Pe. ater were Lonicera spp. (82.9%). There was a greater degree of overlap and competition for animal food, but plant feeding overlap among the three tit species was low. Two species, P. major and C. caeruleus, showed high feeding overlap for animal items (0.92), whereas Pe. ater and C. caeruleus had no significant feeding overlap. The Coal Tit had a greater tendency to forage for vegetable matter and P. major had a greater tendency to forage for animal matter. Analysis of gizzard contents of P. major and Pe. ater showed that, despite the high degree of feeding overlap, the extent of plant materials consumed indicated no significant competition between the two species. Because Pe. ater is present mostly in autumn and winter, this study cannot establish any degree of competition and food-niche overlap during the breeding season between this and other tit species.     

Prey distribution,foliage structure,and foraging behavior of insectivorous birds in two oak species (<Emphasis Type="Italic">Quercus serrata</Emphasis> and <Emphasis Type="Italic">Q. variabilis</Emphasis>)

We examined foraging behaviors of four insectivorous bird species (Great Tit Parus major, Varied Tit P. varius, Long-tailed Tit Aegithalos caudatus and Japanese White-eye Zosterops japonica) on the two oak species (Q. serrata and Q. variabilis) in relation to fine-scale foliage structures, abundance, and distribution of folivorous insects and physical and chemical characteristics of leaves. There was no difference in the mean number of insects for each oak species, but there was a significant difference in the mean biomass. The distance from twigs or branches to leaf tips or blade-petiole junctions showed that leaves of Q. variabilis were more dispersed than those of Q. serrata. The different size distribution of insects influenced insect sizes selected and foraging maneuvers used by each bird species. Parus major and P. varius fed on beetles (low energy gain) with perch-gleaning (the most energy-saving maneuver) from the upper side of leaves on Q. variabilis, whereas they fed on large lepidopteran larvae (high energy gain) from the lower side of leaves on Q. serrata using a variety of maneuvers (including energy-consuming ones). Both A. caudatus and Z. japonica fed on insects from the lower side of leaves by hang-gleaning and reach-gleaning, respectively. These species appeared to be morphologically adapted to the energy-consuming but more effective maneuvers used to take preys from the undersides of leaves. We hypothesize that differences in foliage structures between closely related species of trees have evolved as a balance between defense against folivorous insects and attraction of insectivorous birds.     

Mammal hair in nests of four cavity-nesting songbirds: occurrence,diversity and seasonality

Capsule: The diversity of mammal hair found in nest linings varied between bird species and with season.

Aims: We examined mammal species composition in the guard hair material of four cavity-nesting songbirds, focusing on their numbers and occurrence, nest predation and seasonality.

Methods: We surveyed 219 nests of four cavity-nesting songbirds breeding in a Central European woodland and identified hairs from 28 mammal species.

Results: Roe Deer Capreolus capreolus hair was the most commonly used hair type in the nests of all four songbird species. This was especially the case in Blue Tit Cyanistes caeruleus nests, which may suggest a preference for Roe Deer hair. The greatest diversity of hairs was found in the nests of Great Tits Parus major, while the lowest was found in the Collared Flycatcher Ficedula albicollis. In flycatchers, 59% of females used only plant material for nest construction. Interestingly, we found a strong seasonal effect in hair use. Flycatcher nests that were initiated early in the season were more likely to contain mammal hair than those initiated later in the season. Similar, albeit weaker, negative seasonal effect was detected in Great and Blue Tit nests. There were no significant effects of any potential anti-predatory functions of mammalian hair in nests.

Conclusion: Our study showed a clear prevalence of Roe Deer in the hair material of all bird species and certain preferences of birds for particular mammal species. When the aim is to detect a wide range of mammal species, for example, during biodiversity surveys, we advise to consider sampling effort and to focus on early breeding birds.     

Winter use of wild bird cover crops by passerines on farmland in northeast England

Capsule Declining farmland species were more abundant in these crops which can be matched to the birds' requirements.

Aims To assess the use of seed-bearing crop by a range of bird species in winter.

Methods The study was carried out over three winters at a site in County Durham (England). Eleven bird species were represented, five of which are nationally targeted for conservation action.

Results Bird abundance was significantly higher where wild bird cover crops were present. Kale Brassica napus and Quinoa Chenopodium quinoa were the most used crop species, although cereals and linseed were also used.

Conclusion Simple crop mixtures can be designed to meet the needs of farmland bird communities. Our results suggest that seed production may be limited within government agri-environment schemes by restrictions on fertilizer use. The agronomy of seed-bearing crops for birds requires further investigation.     

Changing climate and the phenological response of great tit and collared flycatcher populations in floodplain forest ecosystems in Central Europe

This study is based on 47 years of observations (1961–2007) on two common bird species, the Great Tit (Parus major) and the Collared Flycatcher (Ficedula albicollis), and a dominant tree species in their habitat, the English Oak (Quercus robur). The study took place at four research sites in the Czech Republic located in full-grown, multi-aged floodplain forests with no forestry management. An increase in air temperature over the evaluated period clearly influenced the length of phenological phases. The full foliage date of English Oak has advanced by 8.7 days during the past 47 years. Great Tit and Collared Flycatcher populations have reacted to the changing climate in the same way, with first laying date and mean laying date advancing by between 6.0 and 9.0 days. In all cases, the trends are highly significant and consistent over all sites. Despite the ongoing shift in phenological stages toward the beginning of the year, the change does not appear to have led to mistiming in the trophic food chain. Overall, this study shows almost identical rates of change in egg laying dates for both bird species in all the floodplain forests studied, and these trends are coherent with those of English Oak and peak herbivorous caterpillar activity.     

Nestbox orientation: a species-specific influence on occupation and breeding success in woodland passerines

Capsule Nestbox orientation has species-specific influences on nestbox occupation and breeding success for woodland passerines.

Aims To determine if nestbox orientation had an influence upon nestbox selection or breeding success for three co-occurring woodland passerines.

Methods We analysed 15 consecutive years of breeding data (1990–2004) from 295 nestboxes in the UK using circular statistical analyses to examine the influence of orientation upon nestbox occupation and breeding success for three species, Blue Tit Cyanistes caeruleus, Great Tit Parus major and Pied Flycatcher Ficedula hypoleuca.

Results The three species used nestboxes of all orientations during the 15-year period. The frequency of nestbox occupation by Great Tits correlated with orientation (the mean number of nests in boxes oriented south-southwest was lower than the mean number of nests in boxes facing other directions). There was no such relationship for Blue Tits or Pied Flycatchers. Nestbox orientation influenced the breeding success of Pied Flycatcher (the mean number of young to fledge from boxes oriented south-southwest was lower than from boxes facing other directions). There was no such relationship for Blue or Great Tits.

Conclusion Nestbox orientation can be an important influence on occupation and breeding success, but this differed between species. Intriguingly, although the directionality reduced nestbox occupation (Great Tit) and breeding success (Pied Flycatcher) was the same (south-southwest), there was a disparity in the influence of orientation for Great Tit (orientation influenced the frequency of occupation but not success) and Pied Flycatcher (orientation did not influence occupation but did affect success). We discuss these disparities, considering the possible influences of mating strategy, breeding phenology, nestbox microclimate and offspring quality.     

Foraging on human-derived foods by urban bird species

Capsule: Providing peanuts on bird feeders was shown to attract more individuals and more species than providing cheese or bread.

Aims: To investigate how the provision of different human-derived foods affected visit rates of urban birds at bird feeders.

Methods: A fully replicated study design was set up in parkland, offering a binary choice from three food types (peanuts, bread and cheese) on bird tables. Birds were observed by using a scan-sample method.

Results: Peanuts attracted more visits, and a greater diversity of bird species, than cheese or bread. This preference was strongest for Blue Tits Cyanistes caeruleus and Great Tits Parus major, whereas European Robins Erithacus rubecula visited all food types equally, and Blackbirds Turdus merula preferred cheese. Bread was the most consumed food type when measured by mass, but this could be linked to varying bite sizes.

Conclusion: Our results indicate that birds preferred to visit feeding stations with the most protein- and energy-rich foods, but that some birds still chose the carbohydrate-rich bread. The findings indicate that peanuts, rather than household scraps like bread and cheese, attract the highest number of species and individuals to bird tables. The findings will be of interest to the public and to organizations providing information on bird feeding for recreational purposes.     

Habitat associations and breeding bird community composition within the city of Bristol,UK

Capsule Different urban breeding bird communities are associated with different habitat types, but, although community species diversity varies significantly, total bird density does not.

Aims To investigate the association between breeding bird communities and habitats within Bristol, UK and how these communities vary in terms of species diversity and total bird abundance.

Methods Breeding density data for 70 species in the metropolitan area of Bristol, UK were subjected to de‐trended correspondence analysis to identify the number of different communities present and their indicator species. These data were then used to identify patterns of habitat association with each community and differences in species richness and total bird density.

Results Three communities were identified: a rural community associated with woodland, managed grassland and inland water; a suburban community associated with buildings and residential gardens; and an intermediate community that shared some of these habitat characteristics. Species richness, but not total bird abundance, was lowest in the suburban community.

Conclusion The diversity of species in urban areas appears to be most dependent upon the availability of patches of natural and semi‐natural habitats. Residential gardens support fewer species, but those species that are present may be found at high densities.     

Variable effects of the Hen Flea Ceratophyllus gallinae on the breeding success of the Great Tit Parus major in relation to weather conditions

We investigated the effect of an ectoparasite, the Hen Flea Ceratophyllus gallinae (Siphonaptera), on the reproductive success of the Great Tit Parus major, a hole-nesting passerine bird. Parasite levels of cleaned nesting boxes were experimentally manipulated during the egg-laying period of the birds either by spraying nests with pyrethrin or by introducing c. 100 adult fleas, while other nests were left as controls. Only in 2 out of 5 years did hen fleas significantly affect reproductive success. Nestlings from parasitized nests showed reduced body-mass, tarsus-length and condition, whereas wing-length did not differ between nestlings reared with or without fleas. The impact of the fleas on the growth performance of host nestlings was more noticeable in years with lower temperatures and higher precipitation.     

Car traffic along hedgerows affects breeding success of Great Tits Parus major

Capsule?In hedgerows near roads with fast and frequent traffic, the mortality of Great Tit Parus major broods was higher than in hedgerows with less traffic and hedgerows with no disturbance.     

Bacterial microbiota composition of a common ectoparasite of cavity-breeding birds,the Hen Flea Ceratophyllus gallinae

Experimental field studies have demonstrated negative fitness consequences of Hen Flea Ceratophyllus gallinae infestations for bird hosts, yet it is currently unclear whether these negative effects are a direct consequence of flea-induced blood loss or a result of flea-borne pathogen transmission. Here we used a 16S rRNA gene sequencing approach to characterize the bacterial microbiota community of Hen Fleas collected from Great Tit Parus major nests and found that Brevibacterium (Actinobacteria), Staphylococcus (Firmicutes), Stenotrophomonas (Proteobacteria), Massilia (Proteobacteria), as well as the arthropod endosymbionts ‘Candidatus Lariskella’ and ‘Candidatus Midichloria’ were most abundant. We found evidence for the occurrence of Staphylococcus spp. in Hen Fleas, which may cause opportunistic infections in bird hosts, but not of other known pathogens commonly transmitted by other flea species, such as Bartonella spp. or Rickettsia spp. However, Hen Fleas might transmit other pathogens (e.g. viruses or bacteria that are not currently recognized as bird pathogens), which may contribute to the negative fitness consequences of Hen Flea infestations in addition to direct blood loss or secondary infections of wounds caused by biting fleas.     

Vaterschaftsnachweise bei vier ungew?hnlich dicht benachbart brütenden Kohlmeisen-Paaren (Parus major)

Zusammenfassung Die Untersuchung erfolgte mit Hilfe des DNA-Fingerprinting. Von 34 Kohlmeisen-Nestlingen aus 4 Bruten, die ungewöhnlich dicht benachbart aufgezogen wurden, ging nur ein Jungvogel auf Kopulation außerhalb des Paarbundes seitens des Weibchens zurück. Dieser vergleichsweise niedrige Anteil könnte unter Umständen auf eine effektive Partnerbewachung als Folge der großen Nähe zwischen den vier Nisthöhlen bzw. Revieren zurückzuführen sein.

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Paternity analysis of four Great Tit (Parus major) broods in unusually close proximity

Summary The results were obtained by DNA fingerprint analysis. Only one out of 34 nestlings from four Great Tit broods situated unusually close to each other was due to EPCs of the female. This low rate of EPY may be explained by attributable to effective mate guarding in consequence of the close proximity of the four nest holes and associated territories.

     

Between-species correlations in the number of migrants at Ulmeth?chi (Switzerland)

We analysed the number of autumn migrants at a bird ringing station over 41 years in the Jura mountains of Switzerland. For 12 irruptive or potentially irruptive bird species, the correlations between their numbers per year were calculated and the species were clustered accordingly. We found high correlations in the number of migrants between the Coal Tit Periparus ater, Great Tit Parus major and Blue Tit Cyanistes caeruleus. Most correlations of passage number between species pairs changed dramatically over time. Only Blue Tit and Coal Tit showed continuously high correlation in this respect. The variation and changes over time in between-species correlations in the number of migrants needs more attention.     

Winter feeding influences the cost of living in boreal passerines

The plastic regulation of internal energy reserves is acknowledged as the main adaptive response to winter conditions of resident small birds in northern latitudes, a strategy that may be altered whenever human‐supplemented food is available. We investigated the effects of supplementary feeding on the energy management strategy of two wild passerine species, the Willow Tit Poecile montanus and Blue Tit Cyanistes caeruleus, wintering in boreal conditions by measuring body mass and the energy cost of living, i.e. basal metabolic rate. Individuals of both species were heavier, larger and exhibited a higher energy cost of living when captured at the feeders than were individuals captured away from feeders. Fed Willow Tits expended more energy in maintenance, although this difference disappeared once mass was accounted for. Conversely, Blue Tits at feeders had higher mass‐adjusted energy cost of living, but only at low ambient temperatures. The results indicate that winter feeding has species‐specific effects on overall energy management strategy and modifies the response to environmental conditions of wintering passerines.     

Evidence for declines in populations of grassland-associated birds in marginal upland areas of Britain

Capsule We report large declines among summer populations between 1968–80 and 2000.

Aim To assess changes in the status of breeding populations of birds in pastoral uplands.

Methods Volunteer observers revisited 13 areas of marginal upland in Britain where Common Birds Census data were collected during 1968–80. This allowed the status of 35 bird species to be examined over about 20 years and to make a comparison between grassland-based and woodland-based species.

Results For 12 species the decline in abundance was significant, particularly among passerines, such as Skylark Alauda arvensis, Wheatear Oenanthe oenanthe, Whinchat Saxicola rubetra, Yellow Wagtail Motacilla flava and Yellowhammer Emberiza citrinella, each of which declined by over 80%. Redshank Tringa totanus, Yellow Wagtail, Dipper Cinclus cinclus, Whinchat, Wheatear, Ring Ouzel Turdus torquatus and Yellowhammer were found on less than half the number of plots on which they were originally recorded. Most declining species were associated with grassland for nesting and foraging, compared to those species that increased (Wood Pigeon Columba palumbus, Pied Wagtail Motacilla alba, Carrion Crow Corvus corone, Jackdaw C. monedula and Goldfinch Carduelis carduelis) that were less specialized in their habitat requirements. Woodland or woodland edge species showed no significant change in status, suggesting that population declines among grassland species were not due to lower observer effort between recording periods.

Conclusion Long-term changes to grassland ecosystems in marginal upland areas of Britain may have influenced the status of bird populations.