Breeding success of the great tit Parus major in relation to attributes of natural nest cavities in a primeval forest

An overlap in attributes of nest cavities used by Great Tit Parus major across Eurasia suggests similar nest site preferences within the geographical range, although the drivers of these preferences are unclear. To determine whether preferred cavities provide conditions enhancing successful reproduction, we investigated the breeding performance of Great Tits in relation to tree cavity characteristics using data collected during 2008–2011 in primeval conditions (Białowieża National Park, Poland). Here, tree cavities are diverse and superabundant but nesting birds are at risk from a variety of predators. According to expectations, nest losses were high (60 % of Great Tit nests failed), mostly due to predation (69 % of nest failures). The risk of nest failure varied with nest cavity attributes. Compared to successful nests, failures were situated higher above the ground and placed closer to the cavity entrance. Very deep cavities with narrow entrances and strong livings walls provided effective protection against larger predators (e.g., martens, woodpeckers), unable to enter the cavity or pull out the contents. Yet, such holes were no barrier for the smallest predators (e.g., Forest Dormouse Dryomys nitedula), which were able to enter any Great Tit nest cavity and destroyed most of the nests. Avoiding small predators would give a selective advantage to the birds, but this seems hardly possible to achieve. We conclude that tree cavities preferred by the tits show a combination of properties which are a compromise for avoiding predation (the strongest selective pressure) and providing the minimum requirements (sufficient nest illumination, microclimate, protection against nest soaking) for development and growth of young

Dissection of the Human Multipotent Adult Progenitor Cell (MAPC) Secretome by Proteomic Analysis

Digitalitzat per Artypla

Microclimate in tree cavities and nest-boxes: implications for hole-nesting birds

The provision of nest-boxes is widely used as a conservation intervention to increase the availability of cavities for hole-nesting birds, particularly in managed forests, but it is uncertain whether nest-boxes are an appropriate substitute for tree cavities. Tree cavities and nest-boxes may differ in many aspects, including microclimate, but there are few data with which to examine this. We measured the air temperature and relative humidity in vacant tree cavities previously used by breeding marsh tits Poecile palustris (a non-excavating forest passerine) and in nest-boxes provided for this species that had similar dimensions to natural nest sites, and we compared values from both with ambient conditions. We examined how tree cavity characteristics influenced microclimate and if similar conditions were replicated in nest-boxes. Tree cavities, particularly those in thicker parts of trees, were more efficient thermal insulators, with temperature extremes dampened to a greater extent relative to ambient values. In contrast, the nest-boxes provided poor insulation with negligible buffering against ambient temperatures. Mean daily relative humidity was high (on average c. 90%) in tree cavities, which all had walls of living wood, and this averaged 24% higher than in nest-boxes at comparable ambient conditions (mean humidity 76–78%). These results support previous studies that incorporated various types of tree cavities and nest-boxes, indicating that the environment within nest-boxes differs significantly from that of tree cavities. We conclude that providing nest-boxes may affect microclimatic conditions available for cavity-users, which may have ecological implications for nesting birds

Social structure of coal tits Periparus ater in temperate deciduous forest

Analysis of the impacts of social structure on the behaviour and life history of birds is a rapidly developing area of ornithology. Such studies commonly focus on the Paridae (tits and chickadees) as a model group, but detailed assessment of the basic social structure is lacking for many parids, particularly in the non-breeding season. Such baseline information is essential for understanding the organisation of bird populations, including associations between individuals within social and spatial networks. We assessed the non-breeding (autumn-winter) and spring (i.e. breeding season) social structure of Coal Tits Periparus ater in broadleaved forest in southern Britain. Coal Tits were found to be resident and sedentary in this habitat, with birds remaining close to their spring territories during the non-breeding season and associating in small groups averaging 3-4 individuals. Associations were variable, however, with no evidence of stable flock membership, group territoriality or strong pair bonds during autumn-winter. The non-breeding social structure did not change between years of high and low population density, being most similar to a 'basic flock' organisation. This differed from that expected of a food-hoarding parid and contradicted some earlier classifications, highlighting the potential plasticity of social behaviour between bird populations. Such variation can inform the understanding of the evolution of avian social structures and associated behavioural traits, such as food hoarding, and aid the interpretation of intraand inter-specific differences in behaviour

Multi-scale settlement patterns of a migratory songbird in a European primeval forest

The drivers of animal settlement are core topics in ecology. Studies from primaeval habitats provide valuable but rare insights into natural settlement behaviour, where species are unconstrained by habitat fragmentation and modification. We examined whether territorial male songbirds (wood warblers Phylloscopus sibilatrix) exhibited clustered distributions when settling in extensive primaeval forest. We tested whether settlement patterns were consistent between years, the influence of habitat preference and the spatial extent of these processes. Remote sensing (airborne LiDAR and satellite multi-spectral) and field survey data were combined to investigate settlement at the landscape (tens of km2), plot (46–200 ha) and microhabitat (20 m diameter) scales, by sampling across 5.9 × 4.5 km of the Białowieża National Park (Poland) during 2018–2019. We assessed bird distribution patterns using nearest neighbour analyses, and habitat preference with generalized linear mixed models. Variation in bird density between plots and years was suggestive of large-scale clustering at the landscape scale. At the local plot scale, any clustering was masked by territoriality, with birds appearing dispersed or randomly distributed. At the microhabitat scale within territories, birds preferred a tall, closed canopy forest structure and avoided a dense herb layer of wild garlic patches. Settlement appeared unconstrained by the availability of preferred habitat at the plot scale, which remained unsaturated. Wood warbler settlement apparently involved hierarchical decisions at multiple spatial scales, compatible with potential social attraction, territoriality, habitat preference or predator avoidance. Selecting an appropriate scale of analysis is an important consideration when assessing the clustering of territorial species

CD25 expression distinguishes functionally distinct alloreactive CD4+ CD134+ (OX40+) T-cell subsets in acute graft-versus-host disease

AbstractCD134 (OX40) is expressed on activated CD4+ donor T cells in allogeneic stem cell transplant recipients with acute graft-versus-host disease. The data presented here reveal that differential expression of CD25 by CD4+ CD134+ T cells allows separation of these activated cells into 2 phenotypically and functionally distinct alloreactive T-cell subsets. These subsets exhibit distinct tissue associations, with CD4+ CD134+ CD25− T cells preferentially found in lymphoid tissues and CD4+ CD134+ CD25+ T cells located in lymphoid tissues and inflamed extralymphoid tissues. The CD25− T-cell subset exhibited potent proliferative responses to both concanavalin A and allogeneic host leukocytes. By contrast, the CD25+ T-cell subset proliferated minimally in response to either treatment and inhibited alloantigen-induced proliferation of the CD25− subset. Proliferative unresponsiveness associated with the CD25+ T-cell subset did not extend to cytokine secretion. When stimulated with alloantigen, both CD4+ CD134+ T-cell subsets responded by secreting interferon-γ and interleukin (IL)-10, and neither T-cell subset produced detectable levels of IL-2 or IL-4. Three-day treatment of the CD25+ T-cell subset with IL-2 restored the proliferative responsiveness of these cells to host alloantigens, suggesting that the proliferative unresponsiveness associated with this T-cell subset reflected a requirement for IL-2. The preferential tissue associations and distinct functional properties associated with these separable alloreactive CD4+ CD134+ T-cell subsets suggest that they participate differentially in clinical graft-versus-host disease