Benefits and costs of native reforestation for breeding songbirds in temperate uplands

Global tree planting initiatives may benefit biodiversity depending on woodland type, but ecological effects must be understood when woodland replaces open habitats supporting characteristic wildlife. In the UK's temperate uplands, large-scale reforestation is replacing long-established open ‘moorland’ (heath, bog and grassland) supporting breeding bird communities of conservation importance. We quantified breeding bird species richness and abundance in 8–24 year-old native woodland plantations in Scotland and adjacent moorland and used bird densities to predict potential future abundance changes in woodland and moorland avian indicator species from recent national-level woodland creation policies. Bird species richness at point counts increased with increasing woodland cover, height and age and declined with increasing elevation. Differing abundances of bird species of conservation concern between woodland and moorland were related to their associations with vegetation measures, especially woodland cover and tree species composition. The creation of 54.9 km2 of native woodland in Scotland across 2017 and 2018 predicts reduced Meadow Pipit Anthus pratensis (moorland indicator) abundance of 6214 individuals or 0.13% of current UK population, and increased Willow Warbler Phylloscopus trochilus (indicator of young woodland) abundance of 6040 individuals or 0.13% of current UK population. Native woodland plantations comprised c34% of new woodland creation and the projections should be extended to other woodland types in particular non-native commercial conifer forestry. Native reforestation of open ground offers net gains in bird species richness but could disbenefit open-ground birds including those of conservation concern. Where retention of open-ground species is desired, landscape-scale reforestation should consider both woodland and open-ground wildlife

Remotely sensed variables explain microhabitat selection and reveal buffering behaviours against warming in a climate-sensitive bird species

Fine-scale habitat selection modelling can allow a mechanistic understanding of habitat selection processes, enabling better assessments of the effects of climate and habitat changes on biodiversity. Remotely sensed data provide an ever-increasing amount of environmental and climatic variables at high spatio-temporal resolutions, and a unique opportunity to produce fine-scale habitat models particularly useful in challenging environments, such as high-elevation areas. Working at a 10-m spatial resolution, we assessed the value of remotely sensed data for investigating foraging habitat selection (in relation to topography, microclimate, land cover) in nestling-rearing white-winged snowfinch (Montifringilla nivalis), a high-elevation species highly sensitive to climate change. Adult snowfinches foraged at locations with intermediate vegetation cover and higher habitat heterogeneity, also avoiding extremely warm or extremely cold microclimates. Temperature interacted with other environmental drivers in defining habitat selection, highlighting trade-offs between habitat profitability and thermoregulation: snowfinches likely adopted mechanisms of behavioural buffering against physiologically stressful conditions by selecting for cooler, shaded and more snowy foraging grounds at higher temperatures. Our results matched those from previous studies based on accurate field measurements, confirming the species' reliance on climate-sensitive microhabitats (snow patches and low-sward grassland, in heterogeneous patches) and the usefulness of satellite-derived fine-scale modelling. Habitat suitability models built on remotely sensed predictors can provide a cost-effective method for periodic monitoring of species' habitats both at fine grain and over large extents. Fine-scale models also enhance our understanding of the actual drivers of (micro)habitat selection and of possible buffering behaviours against warming, allowing more accurate and robust distribution models, finer predictions of potential future changes and carefully targeted conservation strategies and habitat management

Ecological factors affecting foraging behaviour during nestling rearing in a high-elevation species, the White-winged Snowfinch (Montifringilla nivalis)

During breeding, parents of avian species must increase their foraging efforts to collect food for their offspring, besides themselves. Foraging trips are thus a key aspect of the foraging ecology of central-place foragers when rearing their offspring. However, studies of the foraging ecology of high-elevation specialists inhabiting harsh environments are scarce. Here we report for the first time quantitative information on ecological determinants of foraging trips in the White-winged Snowfinch (Montifringilla nivalis), a high-elevation specialist threatened by climate warming. We focused on seasonal, meteorological, habitat and social factors affecting distance and duration of foraging trips performed during nestling rearing, recorded by visual observations in the Italian Alps. Based on 309 foraging trips from 35 pairs, we found that trips lasted 6.12 min and foraging areas were located at 175 m from the nest site on average. Trip duration was affected by snow cover (longer at intermediate cover), distance travelled and wind, while distance travelled was affected by snow cover (being higher at intermediate cover) and trip duration. Foraging individuals thus travelled farther and spent more time at areas characterized by intermediate snow cover, implying the presence of snow margins. It is likely that at such snow patches/margins snowfinches collected food for self-maintenance, besides that for their offspring, or collected more food items. Any reduction of snow cover during the breeding season, as expected under current climate warming, will severely alter foraging habitat suitability. Conserving suitable foraging habitats in the nest surroundings will be crucial to buffer such negative impacts

A genus at risk: Predicted current and future distribution of all three Lagopus species reveal sensitivity to climate change and efficacy of protected areas

Aim: Cold-adapted species are considered vulnerable to climate change. However, our understanding of how climate-induced changes in habitat and weather patterns will influence habitat suitability remains poorly understood, particularly for species at high latitudes or elevations. Here, we assessed potential future distributions for a climate-sensitive genus, Lagopus, and the effectiveness of protected areas in tracking shifting distributions. Location: British Columbia, Canada. Methods: Using community science observations from 1970 to 2020, we built species distribution models for white-tailed (L. leucura), rock (L. muta) and willow ptarmigan (L. lagopus) across British Columbia, a globally unique region harbouring all three ptarmigan species. We assessed the impact of climate (direct) and climate-induced habitat change (indirect) on potential future distributions of ptarmigan. Results: White-tailed and rock ptarmigan were associated with colder temperatures and tundra-like open habitats and willow ptarmigan with open, shrub habitats. Future projections based on climate and vegetation scenarios indicated marked losses in suitable habitat by the 2080s (RCP +8.5 W/m2), with range declines of 85.6% and 79.5% for white-tailed and rock ptarmigan, respectively, and a lower 61.3% for willow ptarmigan. Predicted current and future suitable habitat occurred primarily outside of current protected areas (67%–82%), yet range size declined at a less pronounced rate within protected areas suggesting a capacity to buffer habitat loss. Main conclusions: Ptarmigan are predicted to persist at higher elevations and latitudes than currently occupied, with the magnitude of elevation shifts consistent with trends observed elsewhere in the Holarctic. Our spatially explicit assessment of potential current and future distributions of ptarmigan species provides the first comprehensive evaluation of climate change effects on the distribution of three congeneric, cold-adapted species with different habitat preferences and life-history traits. We also highlight the potential role of protected areas in preserving suitable future sites for ptarmigan and other climate-sensitive or high-elevation species

Sink or swim? Modernization of mussel farming methods may negatively impact established seabird communities

Marine aquaculture is the fastest growing sector of global food production and is projected to increase to meet future demand. Expansion and modernization of cultivation methods are needed to reach this target but a cost-benefit evaluation for biodiversity conservation is required to achieve sustainable aquaculture practices. We assess drivers of avian richness and abundance in a long-established seabird community present in a series of longline mussel farms in Italy and in response to a recent modernization process in the farming methodology. Over 2 years (24 surveys) we detected a remarkable diversity (15 species in 5 families) and abundance (n = 5858) of birds, of which 40% (n = 6) are regarded as species of international conservation importance. Our models highlighted that the strongest driver explaining variation in abundance and richness across sites was the type of buoy and the associated cultivation method applied. The older and fast-declining double headrope design, offered greater stability for birds to rest. Conversely, the newer and mechanizable single headrope design dominant method in our study site and projected to replace the older system, was unsuitable for birds. Our findings confirm the function of mussel farms as a sort of marine protected area where low anthropogenic disturbance, higher prey availability and suitable artificial structures promote the establishment of seabird communities with minimal impacts on harvest. However, we suggest that potential modernization of farming methods, important to meet future human demand, needs to be carefully assessed and compensated for, particularly where long-established seabird communities have formed in response to such practices

An objective-based prioritization approach to support trophic complexity through ecological restoration species mixes

Reassembling ecological communities and rebuilding habitats through active restoration treatments require curating the selection of plant species to use in seeding and planting mixes. Ideally, these mixes should be assembled based on attributes that support ecosystem function and services, promote plant and animal species interactions and ecological networks in restoration while balancing project constraints. Despite these critical considerations, it is common for species mixes to be selected opportunistically. Reframing the selection of seed mixes for restoration around ecological objectives is essential for success but accessible methods and tools are needed to support this effort. We developed a framework to optimize species seed mixes based on prioritizing plant species attributes to best support different objectives for ecosystem functions, services and trophic relationships such as pollination, seed dispersal and herbivory. We compared results to approaches where plant species are selected to represent plant taxonomic richness, dominant species and at random. We tested our framework in European alpine grasslands by identifying 176 plant species characteristic of the species pool, and identified 163 associated attributes affiliated to trophic relationships, ecosystem functions and services. In all cases, trophic relationships, ecosystem functions and services can be captured more efficiently through objective-based prioritization using the functional identity of plant species. Solutions (plant species lists) can be compared quantitatively, in terms of costs, species or objectives. We confirm that a random draw of plant species from the regional plant species pool cannot be assumed to support other trophic groups and ecosystem functions and services. Synthesis and Applications. Our framework is presented as a proof-of-concept to help restoration practitioners better apply quantitative decision support to plant species selection to efficiently meet ecological restoration outcomes. Our approach may be tailored to any restoration initiative, habitat or restoration targets where seeding or planting mixes will be applied in active treatments. As global priority and resources are increasingly placed into restoration, this approach could be advanced to help make efficient decisions for many stages of the restoration process

Sex-mediated changes in foraging behaviour according to breeding stage in a monomorphic seabird adapted to rural habitats

In contrast to sexually size-dimorphic species, monomorphic ones rarely show sexual differences in foraging behaviour as such variations have been primarily attributed to dissimilar body size. To investigate this aspect, we analysed foraging behaviour in breeding gull-billed terns, Gelochelidon nilotica, a monomorphic seabird adapted to rural habitats. We equipped 19 breeding birds with GPS devices and assessed differences in foraging behaviour and habitat use according to sex and breeding stage. Foraging trip distance and duration and daily frequencies were influenced by both breeding stage and sex, with females, but not males, performing closer, more frequent and shorter duration trips during chick rearing than incubation. Females, but not males, increased the repeatability of foraging metrics from incubation to chick rearing, while both sexes increased individual foraging site fidelity between the two breeding stages. Agricultural fields were the most exploited habitat for both sexes, but females made more use of aquatic habitats than males, especially during chick rearing. By foraging in different ways and in different habitats, the breeding pair can provide a wider range of prey types to their offspring, maximizing the chances of delivering high quantity and quality of food items under different environmental conditions. Our work provides new additional evidence of sex differences in foraging behaviour of monomorphic species, while highlighting the need to better understand underlying mechanisms driving foraging niche divergence and the consequences for fitness

Thermal niche predicts recent changes in range size for bird species

Species’ distributions are strongly affected by climate, and climate change is affecting species and populations. Thermal niches are widely used as proxies for estimating thermal sensitivity of species, and have been frequently related to community composition, population trends and latitudinal/elevational shifts in distribution. To our knowledge, no work has yet explored the relationship between thermal niche and change in range size (changes in the number of occupied spatial units over time) in birds. In this study, we related a 30 yr change in range size to species thermal index (STI: average temperature at occurrence sites) and to other factors (i.e. birds’ associated habitats, body mass, hunting status) potentially affecting bird populations/range size. We analysed trends of breeding bird range in Italy for a suite of poorly studied cold-adapted animals potentially sensitive to global warming, and for a related group of control species taxonomically similar and with comparable mass but mainly occurring at lower/warmer sites. We found a strong positive correlation between change in range size and STI, confirming that recent climatic warming has favoured species of warmer climates and adversely affected species occupying colder areas. A model including STI and birds’ associated habitats was not so strongly supported, with forest species performing better than alpine open habitat and agricultural ones. In line with previous works highlighting effects of recent climate change on community composition, species’ population trends and poleward/upward distributional shifts, we found STI to be the most important predictor of change in range size variation in breeding birds

Coping with unpredictable environments: fine-tune foraging microhabitat use in relation to prey availability in an alpine species

Microhabitat utilisation holds a pivotal role in shaping a species’ ecological dynamics and stands as a crucial concern for effective conservation strategies. Despite its critical importance, microhabitat use has frequently been addressed as static, centering on microhabitat preference. Yet, a dynamic microhabitat use that allows individuals to adjust to fine-scale spatio-temporal prey fluctuations, becomes imperative for species thriving in challenging environments. High-elevation ecosystems, marked by brief growing seasons and distinct abiotic processes like snowmelt, winds, and solar radiation, feature an ephemeral distribution of key resources. To better understand species’ strategies in coping with these rapidly changing environments, we delved into the foraging behaviour of the white-winged snowfinch Montifringilla nivalis, an emblematic high-elevation passerine. Through studying microhabitat preferences during breeding while assessing invertebrate prey availability, we unveiled a highly flexible microhabitat use process. Notably, snowfinches exhibited specific microhabitat preferences, favoring grass and melting snow margins, while also responding to local invertebrate availability. This behaviour was particularly evident in snow-associated microhabitats and less pronounced amid tall grass. Moreover, our investigation underscored snowfinches’ fidelity to foraging sites, with over half located within 10 m of previous spots. This consistent use prevailed in snow-associated microhabitats and high-prey-density zones. These findings provide the first evidence of dynamic microhabitat use in high-elevation ecosystems and offer further insights into the crucial role of microhabitats for climate-sensitive species. They call for multi-faceted conservation strategies that go beyond identifying and protecting optimal thermal buffering areas in the face of global warming to also encompass locations hosting high invertebrate densities