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Differences in population trends across a species' breeding range are ultimately linked to variation in demographic rates. In small songbirds, demographic rates related to fecundity typically have strong effects on population trends. Populations of a forest songbird, the wood warbler Phylloscopus sibilatrix, have been declining in many but not all regions of the European breeding range. We investigated if clutch size, hatching rate, nest survival and number of fledglings vary across Europe, and if nest survival is related to differences in the regionally dominant nest predator class (birds versus mammals). From 2009 to 2020, we monitored 1896 nests and used cameras at a subsample of 645 nests in six study regions: the United Kingdom (mid‐Wales, Dartmoor, the New Forest), Germany (Hessen), Switzerland (Jura mountains) and Poland (Białowieża National Park). Number of fledglings was lowest in the New Forest (1.43 ± CI 0.23), intermediate in Jura (2.41 ± 0.31) and Białowieża (2.26 ± 0.24) and highest in mid‐Wales (3.02 ± 0.48) and Dartmoor (2.92 ± 0.32). The reason for low reproductive success in the New Forest, Jura and Białowieża was low nest survival, and large clutch sizes in Białowieża did not compensate for high nest losses. High reproductive success in mid‐Wales and Dartmoor was due to high nest survival and large clutch sizes. Overall predation rates were similar everywhere despite variation between the regions in the dominant nest predator class. Unsuccessful nests in mid‐Wales were mainly predated by birds; in Dartmoor, the New Forest, Hessen and Jura similarly by birds and mammals; and in Białowieża exclusively by mammals. Regional reproductive success does not match the population trends recently reported for the wood warbler in the six study regions (i.e. high reproduction ≠ positive trend). Annual survival may be a decisive factor, but it is difficult to quantify for a nomadic species such as the wood warbler that rarely returns to the same breeding locations. [ABSTRACT FROM AUTHOR]

Understanding the foraging behaviour of predators is key to interpreting the role of anti‐predator adaptations of birds in reducing nest losses. Conducting research in primaeval habitats, with a low level of direct human interference, is particularly valuable in the understanding of predator–prey interactions. Using nest cameras, we investigated the identity and behaviour of potential and actual predators appearing at Wood Warbler Phylloscopus sibilatrix nests, and the importance of different predator groups for nest survival, in the primaeval part of Białowieża Forest (Poland). Mammals formed the main predator group (30 of 32 nest depredations), particularly medium‐sized carnivores (24 of 32), which attacked nests more frequently than merely passing by. This contrasted with other species, especially small rodents, which were commonly recorded near nests but rarely attacked them. Most nest attacks (22 of 32) took place at night and nest survival did not depend on nest visibility, indicating a reduced utility of nest concealment in defence against predators using mainly sound or olfaction when hunting. Daily nest survival declined strongly with nest progression (from egg‐laying to fledging of chicks), probably due to increased predator detection of nests containing older and louder chicks, rather than to increasing parental activity at nests during the day. The set of actual nest predators differed from some previous studies in human‐transformed habitats, showing that Wood Warblers may face different threats in modified vs. near‐pristine environments. [ABSTRACT FROM AUTHOR]

Article impact statement: Participation is not a panacea for the Białowieża conflict; scientific evidence exists and can inform valid policy options. [ABSTRACT FROM AUTHOR]

Numerous bird species have advanced their breeding seasons in response to climate warming. These changes were mostly brought about by phenotypic plasticity, i.e. flexible reactions of individual birds, rather than by microevolutionary change. Knowing the limits of plasticity is thus of paramount importance in any attempt to predict possible reactions of birds to climate warming. However, the breeding performance of the same individuals in contrasting environmental conditions, necessary to answer this question, is rarely observed. Here, we provide data on the flexibility in timing of egg-laying of individual marsh tit Poecile palustris females breeding in an extremely late (2013) and early (2014) spring in Białowieża National Park (Poland). In both years the birds stayed in the same places in the primeval old-growth forest, free of direct human influences (no nest-boxes, no additional food). The weather variation was within the range of conditions observed during 40 yr in the study area, and no climate warming occurred in the marsh tit's pre-breeding period. Females (n = 16) shifted the onset of laying by 13-23 (median = 20) days between the seasons. This range of individual flexibility encompasses almost the whole latitudinal range of the breeding dates found across Europe. Such a buffer of plasticity would probably be sufficient for marsh tits to adjust the onset of egg-laying to the forecasted range of climate change. A combination of temperature and photoperiod appears to be involved in fine tuning of the birds' breeding times with spring conditions, but how the birds asses and integrate this information remains poorly understood. [ABSTRACT FROM AUTHOR]

Holes provide the safest nest sites for birds, but they are an underutilized resource; in natural forests there are usually more holes than birds that could use them. Some bird species could be prevented from nesting in holes because of their inability to operate in the low light conditions which occur in cavities. As no visual system can operate in complete darkness some nest cavities could be too dark to be useable even by hole-nesters. Thus, the light conditions within tree cavities could constrain both the evolution of the hole nesting habit, and the nest site choice of the hole-nesting birds. These ideas cannot be tested because little is known about the light conditions in cavities. We took an opportunity provided by ongoing studies of marsh tits Poecile palustris and great tits Parus major breeding in a primeval forest (Białowieża National Park, Poland) to measure illumination inside their nest cavities. We measured illuminance in cavities at daybreak, which is just after the parents commenced feeding nestlings. Only ca 1% of incoming light reached the level of the nest. Illuminance at nests of both species (median = 0.1-0.2 lx) fell within mesopic-scotopic range, where colour vision is impaired. Measurements in model cavities showed strong declines in illumination with distance from the entrance, with light levels typically as low as 0.01 lx at 40 cm from the cavity entrance. Thus cavities can be very dark, often too dark for the use of colour vision, and we suggest that 'lighting' requirements can affect the adoption of specific nest sites by hole nesting birds. We discuss implications of the findings for understanding the adaptations for hole-breeding in birds. [ABSTRACT FROM AUTHOR]

In forests worldwide, tree-cavity supply can limit populations of the 10-40% of bird and mammal species that require cavities for nesting or roosting. Conservation efforts aimed at cavity-using communities have often focused on woodpeckers because, as cavity excavators, they are presumed to control cavity supply. We show that avian excavators are the primary cavity producers in North America (77% of nesting cavities), but not elsewhere (26% in Eurasia and South America; 0% in Australasia). We studied survivorship of 2805 nest cavities and found similar persistence of cavities created by woodpeckers and those created by decay in Canada, but low persistence of woodpecker-excavated cavities in Poland and Argentina. Outside of North America, the ephemeral nature of many woodpecker cavities may render most cavity-using vertebrates critically dependent on the slow formation of cavities by damage and decay. The future of most cavity-using communities will therefore be highly dependent on changing forest policies to stem the current loss of old trees. [ABSTRACT FROM AUTHOR]

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In this paper I argue that prehistoric British forests and their avifauna were similar to those persisting in a near-primeval condition in the Białowieża Forest (Polish/Belarussian border). Therefore, observations in the Białowieża Forest may serve as a baseline against which effects of changes in the British woods can be assessed. The results of long-term (30 years) studies of the breeding birds in the Białowieża National Park are summarized. They reveal that the local avifauna shows some features (high species richness, low population densities, high nest predation and low production of young) regarded as typical for undisturbed tropical forests. It is proposed that high productivity, high population densities and sedentary habits found in many British populations are to a large extent a recent phenomenon, due to forest fragmentation, reduction of predator diversity and changes in forest structure. The necessity to preserve the whole Białowieża Forest – currently seriously threatened by ongoing logging – as a benchmark for future biological studies is underlined. [ABSTRACT FROM AUTHOR]

We looked for evidence of a cost of reproduction in the Marsh Tit Parus palustris living in the last fragments of primeval temperate forest (Białowieża National Park, eastern Poland). Potential nest-holes were superabundant but the birds had to cope with a diverse set of predators, dangerous both to broods and to parents. Taking advantage of the natural variation in realized reproductive investment that this caused in terms of the loss of nests or mates, we expected to find differences in survival and future fecundity between birds which had lost broods (reduced effort), had reared young (controls) or were either provisioning young single-handed or had laid replacement clutches (increased effort). Despite 13 years of observation, even during seasons with very strenuous conditions, we have failed to demonstrate that the observed range of variation in parental investment caused any demographic cost of reproduction. Incubating females were regularly killed on the nest, which could indicate the existence of a cost operating in the earlier stages of the breeding cycle. Overall, these results suggest that the reproductive rate in Marsh Tits is not controlled proximately by reproductive cost. [ABSTRACT FROM AUTHOR]

This article presents systemic hurdles to preservation of primeval forests and then provides a more detailed description of the situation of the Bialowieza Forest located on the border of Poland and Belarus. Systemic hurdles include: the use of terminologies as tools for primeval forest destruction; the existence of a primeval forest; the absence of legal mechanisms to preserve ecological and evolutionary processes; and roadblocks. The retention of the Bialowieza Forest is important because: it is a biodiversity hot spot; it is the only place one can still observe ecological and evolutionary processes once typical of the biome of deciduous and mixed-deciduous European forests; and continuous forestry operations since 1915 have resulted in substantial changes in the structure of forest habitats.

Geometry and interaction energy in complexes of the Ph-L type (L = Ar, N2, CO, H2O, NH3, CH4, CH3OH, CH3F) involving neutral or cationic phenol were determined using the density functional theory formalism based on the minimization of the total energy bifunctional and gradient-dependent approximations for its exchange-correlation and nonadditive kinetic-energy parts. For the neutral complexes the calculated interaction energies range from 1 kcal/mol for the Ph-Ar complex to about 10 kcal/mol for Ph-NH3. The interactions are stronger if the cationic phenol is involved (up to 25 kcal/mol). It is found, except for neutral Ph-Ar, that the hydrogen-bonded structure is more stable than the π-bound one. Calculated interaction energies (De) correlate well with the experimental dissociation energies (D0). [ABSTRACT FROM AUTHOR]

The Kohn–Sham equations with constrained electron density (KSCED) embedding formalism of Wesołowski and coworkers was originally developed and is good for the case of two weakly interacting molecular regions with weakly overlapping densities, such as might be expected in describing solvation. A generalization is given here for the case of three molecular regions with strongly overlapping densities with the idea that this generalized theory can offer a better description of embedding in the context of situations that might be encountered in, for example, chemisorption on surfaces or active sites in enzymes. This three-partition generalization includes the original two-partition formalism as a special case. Time-dependent response theory equations are then developed for the two- and three-partition theories for application to the problem of the calculation of polarizabilities and other response properties, including excitation spectra, of embedded molecules or molecular structures. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2004 [ABSTRACT FROM AUTHOR]

A proposal that nest predation is the most important selective pressure shaping nest-site use of Marsh Tits Parus palustris was checked in a long-term study (almost 500 nests) carried out in the Białowieża National Park (eastern Poland) in primeval conditions, where the birds breed in natural holes and their nests are at risk from a variety of predators. It was predicted that predation rates would depend on hole attributes, so that Marsh Tits should use the most secure holes. Predation was responsible for 70% of total nest losses. Predation risk depended on hole attributes. Nests in dead wood were predated significantly more often than those in live wood. Nests in old woodpecker holes were predated more frequently than nests in holes of other origin, and nests situated closer to the entrance were more at risk than ones further from it. The entrance size did not influence overall predation risk, but small entrance size was important in preventing access by larger predators. These differences can account for the very rare use of holes in dead wood or of woodpecker holes, the fact that they nest in holes with small entrances and relatively far from the entrance. It is concluded that the patterns of nest-site use found in this species are best explained as anti-predator adaptations, which have evolved and are maintained by the pressure of nest predators. This study also indicates the possible limits of, and constraints on, these adaptations. [ABSTRACT FROM AUTHOR]