Dead wood is important for woodpeckers, providing foraging, roost and nest-sites. In this paper, data from long-term studies of woodpeckers and dead wood in oakwoods in southern England are used to ...examine the dead wood requirements of the three British resident woodpecker species. Both Great Dendrocopos major and Lesser Spotted Woodpeckers Dendrocopos minor select dead trees for nest-sites although the former is able to nest in living trees too. On the other hand a smaller fraction of Lesser Spotted Woodpecker nests are in living trees. Green Woodpecker Picus viridis shows no selection for dead nesting trees. Hence the smallest woodpecker species appears to be most dependent on dead and decaying trees for nest-sites. Great and Lesser Spotted Woodpeckers show no preference for foraging on dead trees although they both make use of dead branches on living trees. Lesser Spotted Woodpeckers forage on smaller branches higher in the tree than Great Spotted Woodpeckers. There has been a trend for increasing dead wood resources in the study woods with both dead wood on the ground and standing dead trees (snags) increasing in the last 20 years. The levels of dead wood are shown to be the result of continual processes of creation and decay. Around 0.5% of oak Quercus spp., Ash Fraxinus excelsior and Hornbeam Carpinus betulus and 3.4% of the birch Betula spp. trees die each year in the woods resulting in a continuity of new dead snags and fallen trees. There is a high turnover of standing dead snags of oak and birch with 95% and 80% annual survival, respectively. Snags are only suitable for nesting Great Spotted Woodpeckers for a few years after their creation. It is suggested that these stand and dead wood dynamics are likely to provide habitats more favourable for the Great Spotted than the Lesser Spotted Woodpecker.
ABSTRACT
Plant populations are regulated by a diverse assortment of abiotic and biotic factors that influence seed dispersal and viability, and seedling establishment and growth at the microsite. ...Rarely does one animal guild exert as significant an influence on different plant assemblages as land crabs. We review three tropical coastal ecosystems–mangroves, island maritime forests, and mainland coastal terrestrial forests–where land crabs directly influence forest composition by limiting tree establishment and recruitment. Land crabs differentially prey on seeds, propagules and seedlings along nutrient, chemical and physical environmental gradients. In all of these ecosystems, but especially mangroves, abiotic gradients are well studied, strong and influence plant species distributions. However, we suggest that crab predation has primacy over many of these environmental factors by acting as the first limiting factor of tropical tree recruitment to drive the potential structural and compositional organisation of coastal forests. We show that the influence of crabs varies relative to tidal gradient, shoreline distance, canopy position, time, season, tree species and fruiting periodicity. Crabs also facilitate forest growth and development through such activities as excavation of burrows, creation of soil mounds, aeration of soils, removal of leaf litter into burrows and creation of carbon‐rich soil microhabitats. For all three systems, land crabs influence the distribution, density and size‐class structure of tree populations. Indeed, crabs are among the major drivers of tree recruitment in tropical coastal forest ecosystems, and their conservation should be included in management plans of these forests.
We present ultraviolet, optical and near-infrared observations of the interacting transient SN 2009ip, covering the period from the start of the outburst in 2012 October until the end of the 2012 ...observing season. The transient reached a peak magnitude of M
V
= −17.7 mag, with a total integrated luminosity of 1.9 × 1049 erg over the period of 2012 August-December. The light curve fades rapidly, dropping by 4.5 mag from the V-band peak in 100 d. The optical and near-infrared spectra are dominated by narrow emission lines with broad electron scattering wings, signalling a dense circumstellar environment, together with multiple components of broad emission and absorption in H and He at velocities in the range 0.5-1.2 × 104 km s−1. We see no evidence for nucleosynthesized material in SN 2009ip, even in late-time pseudo-nebular spectra. We set a limit of <0.02 M on the mass of any possible synthesized 56Ni from the late-time light curve. A simple model for the narrow Balmer lines is presented and used to derive number densities for the circumstellar medium in the range ∼109-1010 cm−3. Our near-infrared data do not show any excess at longer wavelengths, and we see no other signs of dust formation. Our last data, taken in 2012 December, show that SN 2009ip has spectroscopically evolved to something quite similar to its appearance in late 2009, albeit with higher velocities. It is possible that neither of the eruptive and high-luminosity events of SN 2009ip were induced by a core collapse. We show that the peak and total integrated luminosity can be due to the efficient conversion of kinetic energy from colliding ejecta, and that around 0.05-0.1 M of material moving at 0.5-1 × 104 km s−1 could comfortably produce the observed luminosity. We discuss the possibility that these shells were ejected by the pulsational pair instability mechanism, in which case the progenitor star may still exist, and will be observed after the current outburst fades. The long-term monitoring of SN 2009ip, due to its proximity, has given the most extensive data set yet gathered of a high-luminosity interacting transient and its progenitor. It is possible that some purported Type IIn supernovae are in fact analogues of the 2012b event and that pre-explosion outbursts have gone undetected.
Background
Mesh is frequently utilized intraoperatively for the repair of groin hernias. However, patients may request non‐mesh hernia repairs owing to adverse events reported in other mesh ...procedures. To inform surgical safety, this study aimed to compare postoperative complications between mesh and non‐mesh groin hernia repairs and identify other operative and patient‐related risk factors associated with poor postoperative outcomes.
Methods
Ovid MEDLINE and grey literature were searched to 9 June 2021 for studies comparing mesh to non‐mesh techniques for primary groin hernia repair. Outcomes of interest were postoperative complications, recurrence of hernia, pain and risk factors associated with poorer surgical outcomes. Methodological quality was appraised using the AMSTAR 2 tool.
Results
The systematic search returned 4268 results, which included seven systematic reviews and five registry analyses. Mesh repair techniques resulted in lower hernia recurrence rates, with no difference in chronic pain, seroma, haematoma or wound infection, compared to non‐mesh techniques. Risk factors associated with increased risk of hernia recurrence were increased body mass index (BMI), positive smoking status and direct hernia. These were independent of surgical technique. Patients under 40 years of age were at increased risk of postoperative pain.
Conclusions
Surgical repair of primary groin hernias using mesh achieves lower recurrence rates, with no difference in safety outcomes, compared with non‐mesh repairs. Additional risk factors associated with increased recurrence include increased BMI, history of smoking and hernia subtype.
To inform surgical safety, we performed a rapid review comparing postoperative complications between mesh and non‐mesh groin hernia repairs and identify other operative and patient‐related risk factors associated with poor postoperative outcomes. We found that surgical repair of primary groin hernia utilizing mesh results in lower recurrence rates with no difference in safety outcomes, compared to non‐mesh repairs. Other factors associated with increased incidence of recurrence include increased BMI and smoking history.
Twenty-five-year population trends of 42 bird species rare as breeders in the UK were examined in relation to changes in climatic suitability simulated using climatic envelope models. The effects of ...a series of potential 'nuisance' variables were also assessed. A statistically significant positive correlation was found across species between population trend and climate suitability trend. The demonstration that climate envelope models are able to retrodict species' population trends provides a valuable validation of their use in studies of the potential impacts of future climatic changes.
Capsule The provision of supplementary food in early spring led to an advance in laying date and increased productivity for the Great Spotted Woodpecker.Aims To use the experimental provision of ...supplementary food in the prebreeding period to investigate the role of food supply in determining laying date, subsequent synchrony with natural food availability and the impact on productivity for the Great Spotted Woodpecker.Methods Supplementary food in the form of fat blocks was provided at 13 feeding stations distributed over half of a 100-ha study wood from early February until late April 2011 with the other half of the wood left unfed. The breeding parameters (first egg date, clutch size, number of young fledged per nest and nest success) of Great Spotted Woodpeckers were monitored throughout the wood and data from the ‘fed’ and ‘unfed’ zones compared. The same breeding parameters collected throughout the wood in the five preceding years (2006–10) when there was no supplementary feeding were used to provide control data. The temporal pattern in the abundance of the main natural prey was monitored using caterpillar frass traps.Results In 2011, the mean first egg date for woodpecker nests in the fed zone of the wood was 4–5 days earlier than for those nests in the unfed zone. Nests in the fed zone were almost twice as productive as those in the unfed zone even though the supplementary feeding stopped before the main period of chick rearing. There were no differences in the breeding parameters in the two zones of the wood in the control years when there was no supplementary feeding. 2011 was a very warm spring and the natural prey abundance peaked very early so that none of the woodpeckers were well synchronized with their main breeding season prey. However, the small advancement in first egg date meant the supplemented birds were better synchronized than the controls.Conclusion The response of Great Spotted Woodpeckers to supplementary feeding suggests they may be limited in their ability to shift their breeding period to maintain synchrony with their natural prey in the breeding season. This has important implications for the response of the birds to warm springs which are expected to be more frequent under future climate change. Use of garden feeders by Great Spotted Woodpeckers has the potential to increase breeding success and may be one of the many factors contributing to their current population increase.
Relative and almost linking systems Davis, James A.; Polhill, John B.; Smith, Ken W.
Journal of algebraic combinatorics,
15/8, Letnik:
50, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Collections of difference sets called linking systems have been used to construct new families of linked systems of symmetric designs. In this paper, we define relative and almost linking systems, ...collections of difference sets and almost difference sets with very similar linking properties to linking systems. These linking systems have connections to bent sets and vectorial bent functions. We construct examples of relative and almost linking systems using a technical lemma.
Capsule There is no evidence of widespread significant nest-site competition in Britain or the Western Palearctic between cavity-nesting birds and bumblebees or social wasps. Aims To investigate ...competition between cavity-nesting birds and bumblebees and wasps, particularly the range-expanding Tree Bumblebee, Saxon Wasp and European Hornet in Britain, and review evidence throughout the Western Palearctic. Methods We compared field data from English and Polish studies of tits and woodpeckers breeding in nest-boxes and/or tree holes to assess nest-site competition with bumblebees and wasps. We reviewed the literature quantifying nest-site competition between birds and these insects in the Western Palearctic. Results Bumblebees and wasps are capable of usurping small passerines from nests. In England, these insects commandeered a mean annual 4.1% of tit nests initiated in nest-boxes; occurrence of hornets showed a long-term increase, but not other wasps or bumblebees. Across the Western Palearctic, insect occupation of nest-boxes was generally low, and was lower in England than in Poland. No insects were discovered in tree cavities, including those created by woodpeckers (Picidae). Conclusion Nest-site competition between cavity-nesting birds and bumblebees and wasps appears to be a ‘nest-box phenomenon’, which may occasionally interfere with nest-box studies, but appears negligible in natural nest-sites.
In 2020, nine major UK shooting and rural organisations proposed a voluntary transition from the use for hunting of lead shotgun ammunition to non-lead alternatives. The major food retailer Waitrose ...& Partners has announced its intention to move to not supplying game meat products from animals killed using any kind of lead ammunition and the National Game Dealers Association announced a plan for a similar policy to be implemented in 2022. The SHOT-SWITCH research project, which is intended to monitor the progress of these voluntary initiatives, began in the 2020/2021 shooting season. The project monitors changes in the proportions of wild-shot common pheasants Phasianus colchicus available to consumers in Great Britain that had been killed using lead and non-lead shotgun ammunition, as assessed by using inductively coupled plasma atomic emission spectrometry to identify the composition of shotgun pellets recovered from carcasses. In 2020/2021, 99.4% of the pheasants sampled had been killed using lead ammunition. We report here further results from this study for the 2021/2022 season. We found that 99.5% of the 215 pheasants from which shotgun pellets were recovered had been killed using lead ammunition. We conclude that the shooting and rural organisations’ joint statement and two years of their considerable efforts in education, awareness-raising and promotion, have not yet had a detectable effect on the ammunition types used by hunters who supply pheasants to the British game meat market.
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