Jarosław Wawrzyniak

Effects of nest characteristics on breeding success of Great Tits Parus major

Abstract. In this study, nest characteristics (size and proportions of basic components) were not correlated with the timing of breeding. Clutch size was negatively correlated with total nest mass but positively correlated with the proportion of the mass of the lining in the total nest mass. Analyses of hatching and fledging success showed that the quantity and proportion of moss in the nest structure as well as the nest size influenced the performance of eggs and nestlings at the nest. We suggest that variation in nest size and composition may be due to several contradictory pressures associated with the need to keep the moisture and temperature in the nest relatively constant, to protect the brood from predation, and to control sanitary standards.

Avian Feathers as Bioindicators of the Exposure to Heavy Metal Contamination of Food

The aim of this study was to determine the possibility of using feathers of blue tit nestlings to assess the level of endogenous accumulation of lead. For this purpose we conducted an experiment with lead application to randomly chosen nestlings from eight randomly drawn broods. Five days after the exposure, feathers of lead-treated nestlings had significantly higher lead concentrations than control nestlings. This result suggests that feathers can be used as reliable non-destructive bioindicators to assess the level of heavy metals originating from contaminated food, which is of great significance for comparative studies on ecological consequences of pollution.

Spatial and Temporal Variation in Heterophil-to-Lymphocyte Ratios of Nestling Passerine Birds: Comparison of Blue Tits and Great Tits

Environmental factors affecting trophic conditions act as stressors on nestling altricial birds. Access of parental birds to a sufficient supply of food in a limited period of the nestling stage differ in time and space, depending on nesting habitat, prey density and weather conditions. Heterophil-to-lymphocyte ratio (H/L) is considered as a reliable indicator of prolonged stress reaction in birds. In this study we examine if variation in H/L shows consistent spatio-temporal patterns in nestlings of two parids, blue tit Cyanistes caeruleus and great tit Parus major. We found that blue tit nestlings had on average higher H/L than great tit nestlings, which corresponds with the ecological sensitivity of these species. In both species H/L was higher in a poor parkland habitat than in a high quality forest habitat. In nestling blue tits, higher H/L values occurred in years characterized by more extreme weather conditions and worse caterpillar availability. Such consistent patterns of variation in the H/L ratio of nestling blue tits and great tits suggest that, when age-dependent effects are controlled, the ratio can be used as an indicator of physiological stress that is generated by food-related stressors differing in space and time. In particular, elevated H/L ratios are indicative of human-induced changes in the structure of breeding habitats.

Egg size variation in Blue Tits Cyanistes caeruleus and Great Tits Parus major in relation to habitat differences in snail abundance

Abstract. Wild passerines, especially tits, utilize snail shells as the main source of calcium necessary for laying females to construct egg shells. This research found that the two study areas, representing two habitat types — a mature deciduous forest and a human-disturbed parkland — are inhabited by different snail assemblages: both species richness and density are much higher in the parkland than in the forest. This means that less calcium is available to female tits in the forest than in the parkland, which could result in calcium limitation in the former habitat. Egg size traits, i.e. volume, length and breadth, in the Blue Tit show a consistent long-term pattern of variation that reflects the pattern of calcium availability: egg trait values are higher in the parkland than in the woodland. No habitat-related variation in egg size traits was found in the Great Tits. We suggest that the lack of a relation between Great Tit egg characteristics and snail availability results from the higher ecological plasticity of this species in comparison with the Blue Tit, including its ability to exploit alternative sources of calcium.

Extreme weather event in spring 2013 delayed breeding time of Great Tit and Blue Tit

The impact of climatic changes on life cycles by re-scheduling the timing of reproduction is an important topic in studies of biodiversity. Global warming causes and will probably cause in the future not only raising temperatures but also an increasing frequency of extreme weather events. In 2013, the winter in central and north Europe ended late, with low temperatures and long-retained snow cover—this extreme weather phenomenon acted in opposition to the increasing temperature trend. In 2013, thermal conditions measured by the warmth sum in the period 15 March–15 April, a critical time for early breeding passerines, went far beyond the range of the warmth sums for at least 40 preceding years. Regardless of what was the reason for the extreme early spring 2013 and assuming that there is a potential for more atypical years because of climate change, we should look closely at every extreme phenomenon and its consequences for the phenology of organisms. In this paper, we report that the prolonged occurrence of winter conditions during the time that is crucial for Blue Tit (Cyanistes caeruleus) and Great Tit (Parus major) reproduction caused a substantial delay in the onset of egg laying in comparison with typical springs.

Long-Term Variation in Laying Date and Clutch Size of the Great Tit Parus major in Central Poland: A Comparison between Urban Parkland and Deciduous Forest

Summary. Numerous studies from different locations in Europe show that nest-box populations of tits in urban areas lay earlier and produce fewer eggs than do tits in rural areas. We collected data on laying dates and clutch size in two great tit Parus major populations nesting in oak deciduous forest and urban parkland areas, only about 10 km apart, in central Poland over 11 years. The abundance of caterpillars, the optimal food of breeding tits, at both breeding areas was also quantified. We analysed long-term trends in the timing of egg laying and clutch size. We focused on the effects of year, habitat type, insect availability and weather conditions shortly before egg laying on the patterns of variation in laying date and clutch size. In general, our study supports earlier generalisations on urban and rural tit populations. In particular, our finding that great tits initiated breeding consistently earlier in the urban site than in the forest area supports earlier studies on urbanised birds. The mean laying date was strongly and negatively associated with air temperature between 15 March and 15 April in both habitats. Mean clutch size was lower in the parkland than in the forest population, at least partly in response to the greater abundance of caterpillars in the forest. A novel result of this study is that clutch size differed between habitats to a varying degree in different years, in association with a stronger response to caterpillar abundance in the forest than in the park. Clutch size tended to decline with the progress of the breeding season within years in the parkland site, especially in “early years”, but not in the forest habitat.

Effects of brood size manipulation on physiological condition of nestling Blue Tits Cyanistes caeruleus

Abstract. Producing high quality offspring of good logical performance, able to survive to independence and, then, to reproductive maturity is a major component of life history strategies. The ability of nestling altricial birds to develop a good physiological condition depends to a large extent on the amount and quality of food provided by parents, as well as other aspects of parental care. We hypothesized that experimental changes to the original brood size should affect both parental Blue Tits and their offspring, resulting in corresponding changes in the body condition of the nestlings. Over two breeding seasons, using two habitat sites, we conducted an experiment with two manipulative treatments applied to broods of three-day-old nestlings — the reduction or enlargement of broods by three nestlings, and one non-manipulative control treatment. Our aim was to test whether the experiment would affect a number of different measures of nestling condition: blood concentrations of hemoglobin and glucose, heterophil-to-lymphocyte ratio and morphometric condition index, all being analyzed when the nestlings were 13 days old. We found no effect in the case of hemoglobin, despite the fact that it had previously been shown to be sensitive to large-scale differences in trophic conditions between habitats and years and to the experimental removal of nest parasites. All the remaining variables, i.e. heterophil-to-lymphocyte ratio, glucose concentration and morphometric condition index, responded to the experimental treatments, showing different but reasonable patterns of variation. We suggest that an experimental increase in brood size definitely hinders the development of nestling physiological condition, but even an experimental reduction of broods can affect some physiological indicators (glucose), probably because of readjustments in the feeding rate.

Landscape patterns of variation in blood glucose concentration of nestling blue tits (Cyanistes caeruleus)

Integration of landscape ecology and conservation physiology has been recommended as a potentially useful way to investigate consequences of human-induced changes in habitats for animal populations. A central goal of this paper was to examine if a simple physiological parameter displays any consistent patterns of spatio-temporal variation. Blood glucose concentration in birds reflects their high metabolic demands and may be influenced by a number of environmental factors. Therefore we present results concerning variation in glucose concentration in the blood of c. 14-day-old nestling blue tits (Cyanistes caeruleus) in central Poland in an 8-year period, 2005–2012, in two landscapes: an urban parkland and a deciduous forest. The most important findings of the study were: (1) mean levels of blood glucose varied markedly among years, most probably due to variable weather conditions, (2) glucose concentrations were significantly higher in the parkland study site than in the forest site, (3) heavier nestlings had lower glucose levels, and (4) high glucose levels were negatively correlated with fledging and breeding success. Thus we have confirmed that a consistent spatio-temporal pattern really exists.

Effects of nest characteristics on reproductive performance in Blue Tits Cyanistes caeruleus and Great Tits Parus major

A major function of birds’ nests is to protect eggs and offspring against temperature fluctuations. Reproductive performance was found to be closely related to nest characteristics in some species. We present results concerning nest attributes and their impact on breeding characteristics in Blue Tits (Cyanistes caeruleus) and Great Tits (Parus major) in central Poland over a three year period, 2012-2014, in an urban parkland and a deciduous forest. In Blue Tits, hatching success was positively affected by the nest lining mass. Clutch size was associated with the lining mass and nest mass, and the number of hatchlings was associated with both the nest mass and lining mass. In Great Tits, hatching success was positively affected by the lining mass and fledging success was positively affected by the nest depth and nest mass. Also, clutch size tended to be related to the nest depth and the number of hatchlings was associated with the lining mass. We found that Blue Tit nests were deeper and heavier than Great Tit nests. There were no differences in nest depth and nest mass between two habitats for both tit species. We conclude that there is a relationship between better quality nests and better breeding performance in both Great Tits and Blue Tits.

Does the threat of European Pine Marten ( Martes martes ) predation influence the height of nests built by Blue Tits ( Cyanistes caeruleus ) and Great Tits ( Parus major )

The major aim of this study was to examine the influence of the European Pine Marten (Martes martes) predation on the heights of nests of Blue Tits (Cyanistes caeruleus) and Great Tits (Parus major) in nestboxes of different security levels. To this end we performed a comparison of nest heights before and after introducing an anti-predator device to two size-types of wooden nestboxes set up in a deciduous forest. Blue Tit and Great Tit nest sizes were influenced by the application of plastic entrance tubes as anti-predator devices that elongated a distance between the entrance and the interior of the nestbox. Nests were taller in nestboxes equipped with anti-predator devices regardless of nestbox size. Nests located in smaller nestboxes were destroyed by Martens more frequently than nests built in bigger nest boxes. Most nest functions in cavity-nesting birds, such as filling the excessive cavity space, maintenance of proper humidity, thermal, light and sanitary conditions for eggs and nestlings, improve with nest sizes. Because, in contrast, the risk of nest predation by martens increases with nest size (height within the nestbox), the nest predation constitute a major factor that constrains cavity-nesting birds in constructing tall nests.