A nestbox trial for British marsh tits Poecile palustris

Two experimental nestbox trials were attempted, which aimed to maximise uptake by Marsh Tits in British woodland. Nestboxes which more closely approximated the dimensions of natural cavities were used more frequently than standard nestboxes, but the overall uptake was low. We conclude that nestboxes are an inefficient method of monitoring Marsh Tits, at least in the British context, and researchers should concentrate efforts on locating and monitoring natural nest sites

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 test how Blue Tits Cyanistes caeruleus and Great Tits Parus major used heterogeneous urban habitat, with the aim of establishing whether breeding birds were selective in the habitat they used when foraging and particularly how they responded to non-native trees and shrubs. We also tested whether they showed foraging preferences for certain plant taxa, such as oak Quercus, which are important to their breeding performance in native woodland. Additionally, we used mixed models to test the impact these different habitat types had 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 in 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 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 urbanisation and this has implications for urban ecosystem function

Airborne lidar for woodland habitat quality monitoring: exploring the significance of lidar data characteristics when modelling organism-habitat relationships

Structure is a fundamental physical element of habitat, particularly in woodlands, and hence there has been considerable recent uptake of airborne lidar data in forest ecology studies. This paper investigates the significance of lidar data characteristics when modelling organism-habitat relationships, taking a single species case study in a mature woodland ecosystem. We re-investigate work on great tit (Parus major) habitat, focussing on bird breeding data from 1997 and 2001 (years with contrasting weather conditions and a demonstrated relationship between breeding success and forest structure). We use a time series of three lidar data acquisitions across a 12-year period (2000–2012). The lidar data characteristics assessed include time-lag with field data (up to 15 years), spatial sampling density (average post spacing in the range of 1 pulse per 0.14 m2–17.77 m2), approach to processing (raster or point cloud), and the complexity of derived structure metrics (with a total of 33 metrics assessed, each generated separately using all returns and only first returns). Ordinary least squares regression analysis was employed to investigate relationships between great tit mean nestling body mass, calculated per brood, and the various canopy structure measures from all lidar datasets. For the 2001 bird breeding data, the relationship between mean nestling body mass and mean canopy height for a sample area around each nest was robust to the extent that it could be detected strongly and with a high level of statistical significance, with relatively little impact of lidar data characteristics. In 1997, all relationships between lidar structure metrics and mean nestling body mass were weaker than in 2001 and more sensitive to lidar data characteristics, and in almost all cases they were opposite in trend. However, whilst the optimum habitat structure differed between the two study years, the lidar-derived metrics that best characterised this structure were consistent: canopy height percentiles and mean overstorey canopy height (calculated using all returns or only first returns) and the standard deviation of canopy height (calculated using all returns). Overall, our results suggest that for relatively stable woodland habitats, ecologists should not feel prohibited in using lidar data to explore or monitor organism–habitat relationships because of perceived data quality issues, as long as the questions investigated, the scale of analysis, and the interpretation of findings are appropriate for the data available

Winter habitat selection by marsh tits Poecile palustris in a British woodland

Capsule: Radio-tracking and remote sensing showed Marsh Tits selected for English Oak Quercus robur trees within large winter home-ranges. Aims: To investigate winter habitat selection by Marsh Tits in a British wood, testing for preferences in tree species and woodland structure. Methods: Thirteen Marsh Tits were radio-tracked during the winter, and home-ranges were derived. Lidar and hyperspectral data were used to compare the vegetation structure and tree species composition of entire home-ranges and the core areas of intensive use within. Instantaneous sampling observations provided further information for tree species utilization. Results: The mean home-range was very large (39 ha, n=13). There were no significant differences in mean tree height, canopy closure, understorey height, or shrub volume between full home-ranges and the core areas of use. Core areas contained a significantly greater proportion of English Oak relative to availability in the full home-ranges. Instantaneous sampling confirmed that English Oak was used significantly more than other trees. Conclusion: Selection for English Oak during winter contrasted with previous studies of breeding territories, indicating that habitat usage varies seasonally and demonstrating the need for habitat selection studies throughout the year. Large home-ranges help to explain the Marsh Tit’s sensitivity to habitat fragmentation

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

Towards forest condition assessment: evaluating small-footprint full-waveform airborne laser scanning data for deriving forest structural and compositional metrics

Spatial data on forest structure, composition, regeneration and deadwood are required for informed assessment of forest condition and subsequent management decisions. Here, we estimate 27 forest metrics from small-footprint full-waveform airborne laser scanning (ALS) data using a random forest (RF) and automated variable selection (Boruta) approach. Modelling was conducted using leaf-off (April) and leaf-on (July) ALS data, both separately and combined. Field data from semi-natural deciduous and managed conifer plantation forests were used to generate the RF models. Based on NRMSE and NBias, overall model accuracies were good, with only two of the best 27 models having an NRMSE > 30% and/or NBias > 15% (Standing deadwood decay class and Number of sapling species). With the exception of the Simpson index of diversity for native trees, both NRMSE and NBias varied by less than ±4.5% points between leaf-on only, leaf-off only and combined leaf-on/leaf-off models per forest metric. However, whilst model performance was similar between ALS datasets, model composition was often very dissimilar in terms of input variables. RF models using leaf-on data showed a dominance of height variables, whilst leaf-off models had a dominance of width variables, reiterating that leaf-on and leaf-off ALS datasets capture different aspects of the forest and that structure and composition across the full vertical profile are highly inter-connected and therefore can be predicted equally well in different ways. A subset of 17 forest metrics was subsequently used to assess favourable conservation status (FCS), as a measure of forest condition. The most accurate RF models relevant to the 17 FCS indicator metrics were used to predict each forest metric across the field site and thresholds defining favourable conditions were applied. Binomial logistic regression was implemented to evaluate predicative accuracy probability relative to the thresholds, which varied from 0.73–0.98 area under the curve (AUC), where 11 of 17 metrics were >0.8. This enabled an index of forest condition (FCS) based on structure, composition, regeneration and deadwood to be mapped across the field site with reasonable certainty. The FCS map closely and consistently corresponded to forest types and stand boundaries, indicating that ALS data offer a feasible approach for forest condition mapping and monitoring to advance forest ecological understanding and improve conservation efforts

Wildlife-friendly farming increases crop yield: evidence for ecological intensification

Ecological intensification has been promoted as a means to achieve environmentally sustainable increases in crop yields by enhancing ecosystem functions that regulate and support production. There is, however, little direct evidence of yield benefits from ecological intensification on commercial farms growing globally important foodstuffs (grains, oilseeds and pulses). We replicated two treatments removing 3 or 8% of land at the field edge from production to create wildlife habitat in 50–60 ha patches over a 900 ha commercial arable farm in central England, and compared these to a business as usual control (no land removed). In the control fields, crop yields were reduced by as much as 38% at the field edge. Habitat creation in these lower yielding areas led to increased yield in the cropped areas of the fields, and this positive effect became more pronounced over 6 years. As a consequence, yields at the field scale were maintained—and, indeed, enhanced for some crops—despite the loss of cropland for habitat creation. These results suggested that over a 5-year crop rotation, there would be no adverse impact on overall yield in terms of monetary value or nutritional energy. This study provides a clear demonstration that wildlife-friendly management which supports ecosystem services is compatible with, and can even increase, crop yields

Wildlife-friendly farming benefits rare birds, bees and plants

Agricultural intensification is a leading cause of global biodiversity loss, especially for threatened and near-threatened species. One widely implemented response is ‘wildlife-friendly farming’, involving the close integration of conservation and extensive farming practices within agricultural landscapes. However, the putative benefits from this controversial policy are currently either unknown or thought unlikely to extend to rare and declining species. Here, we show that new, evidence-based approaches to habitat creation on intensively managed farmland in England can achieve large increases in plant, bee and bird species. In particular, we found that habitat enhancement methods designed to provide the requirements of sensitive target biota consistently increased the richness and abundance of both rare and common species, with 10-fold to greater than 100-fold more rare species per sample area than generalized conventional conservation measures. Furthermore, targeting landscapes of high species richness amplified beneficial effects on the least mobile taxa: plants and bees. Our results provide the first unequivocal support for a national wildlife-friendly farming policy and suggest that this approach should be implemented much more extensively to address global biodiversity loss. However, to be effective, these conservation measures must be evidence-based, and developed using sound knowledge of the ecological requirements of key species

Comparative biometrics of British marsh tits Poecile palustris and willow tits P. montana

Biometrics are commonly used to compare bird species. For Marsh Tits and Willow Tits in Britain there are few biometric data from birds of known age and sex, despite their value for population analyses in estimating the proportion of males and females in samples. Comparing measurements between the two species could also aid identification and the monitoring of these declining species in Britain. We present biometrics for a large sample of Marsh Tits of known age and sex, and new data for Willow Tits, which act as reliable reference material. Overall, adults of both species were larger than first-years and males were larger than females, but not among first-year Willow Tits. Marsh Tits were slightly larger and heavier than Willow Tits, but Willow Tits had proportionately longer tails. Discriminant analyses produced new equations for separating the species based on wing length and the measurement between the shortest and longest tail feathers. Probabilities were generated for estimating Marsh Tit population structure from samples of ringing data, but there was a greater overlap between sexes in Willow Tit measurements. We conclude by discussing issues of measurement accuracy and consistency in the collection and analysis of biometric data

An efficient survey method for estimating populations of marsh tits Poecile palustris, a low-density woodland passerine

Capsule: A playback survey comprising two visits to woodland in early spring can reliably detect Marsh Tits Poecile palustris and permit reasonable estimation of the number of territories. Aims: To assess the efficacy of an efficient survey method for detecting and estimating populations of Marsh Tits. Methods: Detection probability of colour-marked Marsh Tits, surveyed using playback, was assessed with Cormack–Jolly–Seber models. Reliability of territory estimates was compared between colour-marked and largely or wholly unmarked populations. Results: Playback surveys over two visits in early spring were highly effective in detecting individual Marsh Tits. Territory estimates were similar for woods in years where less than 20% of the population was marked compared to years when a higher proportion of birds were colour-marked, although territories may be underestimated in larger woods with unmarked populations. Conclusion: A playback survey comprising two visits in early spring is recommended as an efficient method of surveying Marsh Tit populations and locating individuals. A survey protocol is suggested