6 results on '"Henderson IG"'
Search Results
2. Recommendations to enhance breeding bird diversity in managed plantation forests determined using LiDAR.
- Author
-
Tew ER, Conway GJ, Henderson IG, Milodowski DT, Swinfield T, and Sutherland WJ
- Subjects
- Animals, Biodiversity, Birds physiology, Ecosystem, Forests, Plant Breeding
- Abstract
Widespread afforestation is a crucial component of climate mitigation strategies worldwide. This presents a significant opportunity for biodiversity conservation if forests are appropriately managed. Within forests, structural and habitat diversity are known to be critical for biodiversity but pragmatic management recommendations are lacking. We make a comprehensive assessment of the effects of habitat variables on bird populations using data from over 4000 ha of forested landscape. We combine high-resolution remote sensing data with comprehensive management databases to classify habitat attributes and measure the response of six taxonomic and functional diversity metrics: species richness, Shannon diversity, functional richness, functional evenness, functional divergence, and functional dispersion. We use a novel approach that combines hierarchical partitioning analysis with linear models to determine the relative importance of different habitat variables for each bird diversity metric. The age class of forest stands was consistently the most important variable across all bird diversity metrics, outperforming other structural measures such as horizontal and vertical heterogeneity and canopy density. Shrub density and gap fraction were each significantly associated with one bird diversity metric. In contrast, variables describing within-stand structural heterogeneity (vertical and horizontal) were generally less important while tree species identity (e.g., conifer or broadleaved) was not significant for any bird diversity metric. Each of the six bird diversity metrics had different patterns of independent variable importance and significance, emphasizing the need to consider multiple diversity metrics in biodiversity assessments. Similarly, the optimal resolution for remote sensing metrics varied between structural variables and bird diversity metrics, suggesting that the use of remote sensing data in biodiversity studies could be greatly improved by first exploring different resolutions and data aggregations. Based on the results from this comprehensive study, we recommend that managers focus on creating habitat diversity at the between-, rather than exclusively within-stand scale, such as by creating a matrix of different age classes, to maximize bird diversity. This recommendation for forest managers is powerful yet pragmatic in its simplicity., (© 2022 The Authors. Ecological Applications published by Wiley Periodicals LLC on behalf of The Ecological Society of America.)
- Published
- 2022
- Full Text
- View/download PDF
3. Designing a survey to monitor multi-scale impacts of agri-environment schemes on mobile taxa.
- Author
-
Staley JT, Redhead JW, O'Connor RS, Jarvis SG, Siriwardena GM, Henderson IG, Botham MS, Carvell C, Smart SM, Phillips S, Jones N, McCracken ME, Christelow J, Howell K, and Pywell RF
- Subjects
- Animals, Biodiversity, Birds, Ecosystem, Environment, Agriculture, Butterflies
- Abstract
Agri-environment schemes (AES) are key mechanisms to deliver conservation policy, and include management to provide resources for target taxa. Mobile species may move to areas where resources are increased, without this necessarily having an effect across the wider countryside or on populations over time. Most assessments of AES efficacy have been at small spatial scales, over short timescales, and shown varying results. We developed a survey design based on orthogonal gradients of AES management at local and landscape scales, which will enable the response of several taxa to be monitored. An evidence review of management effects on butterflies, birds and pollinating insects provided data to score AES options. Predicted gradients were calculated using AES uptake, weighted by the evidence scores. Predicted AES gradients for each taxon correlated strongly, and with the average gradient across taxa, supporting the co-location of surveys across different taxa. Nine 1 × 1 km survey squares were selected in each of four regional blocks with broadly homogenous background habitat characteristics. Squares in each block covered orthogonal contrasts across the range of AES gradients at local and landscape scales. This allows the effects of AES on species at each scale, and the interaction between scales, to be tested. AES options and broad habitats were mapped in field surveys, to verify predicted gradients which were based on AES option uptake data. The verified AES gradient had a strong positive relationship with the predicted gradient. AES gradients were broadly independent of background habitat within each block, likely allowing AES effects to be distinguished from potential effects of other habitat variables. Surveys of several mobile taxa are ongoing. This design will allow mobile taxa responses to AES to be tested in the surrounding countryside, as well as on land under AES management, and potentially in terms of population change over time. The design developed here provides a novel, pseudo-experimental approach for assessing the response of mobile species to gradients of management at two spatial scales. A similar design process could be applied in other regions that require a standardized approach to monitoring the impacts of management interventions on target taxa at landscape scales, if equivalent spatial data are available., (Copyright © 2021 The Authors. Published by Elsevier Ltd.. All rights reserved.)
- Published
- 2021
- Full Text
- View/download PDF
4. Evidence for senescence in survival but not in reproduction in a short-lived passerine.
- Author
-
Fay R, Schaub M, Border JA, Henderson IG, Fahl G, Feulner J, Horch P, Müller M, Rebstock H, Shitikov D, Tome D, Vögeli M, and Grüebler MU
- Abstract
Senescence has been studied since a long time by theoreticians in ecology and evolution, but empirical support in natural population has only recently been accumulating. One of the current challenges is the investigation of senescence of multiple fitness components and the study of differences between sexes. Until now, studies have been more frequently conducted on females than on males and rather in long-lived than in short-lived species. To reach a more fundamental understanding of the evolution of senescence, it is critical to investigate age-specific survival and reproduction performance in both sexes and in a large range of species with contrasting life histories. In this study, we present results on patterns of age-specific and sex-specific variation in survival and reproduction in the whinchat Saxicola rubetra , a short-lived passerine. We compiled individual-based long-term datasets from seven populations that were jointly analyzed within a Bayesian modeling framework. We found evidence for senescence in survival with a continuous decline after the age of 1 year, but no evidence of reproductive senescence. Furthermore, we found no clear evidence for sex effects on these patterns. We discuss these results in light of previous studies documenting senescence in short-lived birds. We note that most of them have been conducted in populations breeding in nest boxes, and we question the potential effect of the nest boxes on the shape of age-reproductive trajectories., Competing Interests: None declared., (© 2020 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd.)
- Published
- 2020
- Full Text
- View/download PDF
5. Developing and enhancing biodiversity monitoring programmes: a collaborative assessment of priorities.
- Author
-
Pocock MJ, Newson SE, Henderson IG, Peyton J, Sutherland WJ, Noble DG, Ball SG, Beckmann BC, Biggs J, Brereton T, Bullock DJ, Buckland ST, Edwards M, Eaton MA, Harvey MC, Hill MO, Horlock M, Hubble DS, Julian AM, Mackey EC, Mann DJ, Marshall MJ, Medlock JM, O'Mahony EM, Pacheco M, Porter K, Prentice S, Procter DA, Roy HE, Southway SE, Shortall CR, Stewart AJ, Wembridge DE, Wright MA, and Roy DB
- Abstract
Biodiversity is changing at unprecedented rates, and it is increasingly important that these changes are quantified through monitoring programmes. Previous recommendations for developing or enhancing these programmes focus either on the end goals, that is the intended use of the data, or on how these goals are achieved, for example through volunteer involvement in citizen science, but not both. These recommendations are rarely prioritized.We used a collaborative approach, involving 52 experts in biodiversity monitoring in the UK, to develop a list of attributes of relevance to any biodiversity monitoring programme and to order these attributes by their priority. We also ranked the attributes according to their importance in monitoring biodiversity in the UK. Experts involved included data users, funders, programme organizers and participants in data collection. They covered expertise in a wide range of taxa.We developed a final list of 25 attributes of biodiversity monitoring schemes, ordered from the most elemental (those essential for monitoring schemes; e.g. articulate the objectives and gain sufficient participants) to the most aspirational (e.g. electronic data capture in the field, reporting change annually). This ordered list is a practical framework which can be used to support the development of monitoring programmes.People's ranking of attributes revealed a difference between those who considered attributes with benefits to end users to be most important (e.g. people from governmental organizations) and those who considered attributes with greatest benefit to participants to be most important (e.g. people involved with volunteer biological recording schemes). This reveals a distinction between focussing on aims and the pragmatism in achieving those aims. Synthesis and applications . The ordered list of attributes developed in this study will assist in prioritizing resources to develop biodiversity monitoring programmes (including citizen science). The potential conflict between end users of data and participants in data collection that we discovered should be addressed by involving the diversity of stakeholders at all stages of programme development. This will maximize the chance of successfully achieving the goals of biodiversity monitoring programmes.
- Published
- 2015
- Full Text
- View/download PDF
6. Age-specific differences in the winter foraging strategies of rooks Corvus frugilegus.
- Author
-
Henderson IG and Hart PJ
- Abstract
Foraging efficiency and intraspecific competition were compared between wild adult and immature rooks Corvus frugilegus with respect to flock size. Behavioural time budgets, and observations of prey selection and prey energetic values revealed that adult rooks in large flocks (> 50 individuals) consumed smaller, less profitable prey, but allocated more time to feeding and fed at a faster rate and with greater success than adults in small flocks. By contrast, immature rooks in flocks of more than 30 individuals allocated proportionally less time to feeding, fed at a lower rate and fed with no increase in success rate than when foraging in smaller flocks. Agonistic encounters and the avoidance of adults by immature rooks appeared responsible for such inefficient foraging. Hence immature rooks showed a preference for smaller flocks (< 50 individuals) with low adult: immature ratios while adults preferred larger flocks (> 50 individuals). We discuss the possible influence of competitive disadvantages on immature rook distribution, flock composition and post-natal dispersal.
- Published
- 1991
- Full Text
- View/download PDF
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.