As demand for food increases, a crucial question in conservation is how to limit the negative impacts of agriculture on biodiversity. ‘Land sparing’ has been proposed as a strategy to address this problem, with high-yield agriculture minimising the area of farmland so that other land can be spared for conservation. Research – mostly from tropical regions – suggests that most species would achieve larger populations under a land-sparing strategy than under a strategy in which lower-yielding wildlife-friendly farmland delivers food production over a larger total area. It has been argued, however, that wildlife-friendly farming might be more appropriate away from tropical deforestation ‘frontiers’. In the UK, for example, some species which depend on large areas of unmodified habitat have been lost. Instead, conservationists here are particularly concerned about declining farmland wildlife, which are probably unlikely to benefit from a land sparing strategy. An additional question relates to food demand: what might be the biodiversity consequences of reducing food waste, or making more efficient use of land by consuming fewer animal-derived foods? In a new study published in the Journal of Applied Ecology, scientists from the University of Cambridge, RSPB and BTO estimated UK food demand in 2050 under three scenarios: ‘waste’ (50% reduction in avoidable post-harvest waste), ‘diet’ (50% reduction in animal product consumption) and ‘reference’ (no change in waste or diet). They then designed contrasting land-use strategies which met these levels of demand by either maintaining the UK’s current farmed area and increasing yields just enough to meet demand (‘no-sparing’), or by increasing yields in line with technical upper-bounds, allowing the farmed area to shrink and the area of woodland and wetland habitat to grow. They then estimated the change in population size of 156 breeding bird species data from the Breeding Bird Survey. The study found that, on average, bird populations would decline under the no-sparing scenario but would increase under the sparing scenario. In other words, the benefits to bird populations of large-scale habitat restoration outweigh the costs of higher yields on farmland. Not all species showed the same pattern though: unsurprisingly, woodland and wetland birds did much better under the sparing strategy, whereas farmland birds did much worse. So, the overall benefits of land sparing should be considered in the context of this trade-off. Reducing food demand through changing diets or cutting food waste resulted in more positive bird population trends, but the sparing strategy still outperformed no-sparing when averaged across all species. The study raises questions about land-use policies in the UK and elsewhere, where current agri-environment policies tend to favour wildlife-friendly farming approaches. Land-sparing policies are not without challenge though, and the authors highlight two important caveats. First, land sparing is unlikely to occur without policies which explicitly link yield-growth in one place to habitat restoration in another. Second, the high-yields associated with land sparing must be sustainable in the long-term and minimise the degradation of natural capital such as soil and freshwater.

Global warming has advanced the timing of biological events, potentially leading to disruption across trophic levels. The potential importance of phenological change as a driver of population trends has been suggested. To fully understand possible impacts, there is a need to quantify the scale of these changes spatially and according to habitat type. We studied the relationship between phenological trends, space and habitat type between 1965 to 2012 using an extensive UK dataset comprising 269 aphid, bird, butterfly and moth species. We modelled phenologies using generalized additive mixed models that included covariates for geographical (latitude, longitude, altitude), temporal (year, season) and habitat terms (woodland, scrub, grassland). Model selection showed that a baseline model with geographical and temporal components explained the variation in phenologies better than either a model in which space and time interacted or a habitat model without spatial terms. This baseline model showed strongly that phenologies shifted progressively earlier over time, that increasing altitude produced later phenologies and that a strong spatial component determined phenological timings, particularly latitude. The seasonal timing of a phenological event, in terms of whether it fell in the first or second half of the year, did not result in substantially different trends for butterflies. For moths, early season phenologies advanced more rapidly than those recorded later. Whilst temporal trends across all habitats resulted in earlier phenologies over time, agricultural habitats produced significantly later phenologies than most other habitats studied, probably because of non‐climatic drivers. A model with a significant habitat‐time interaction was the best‐fitting model for birds, moths and butterflies, emphasising that the rates of phenological advance also differ among habitats for these groups. Our results suggest the presence of strong spatial gradients in mean seasonal timing, and non‐linear trends towards earlier seasonal timing that varies in form and rate among habitat types.

Newly published research by BTO has shed light on the differing fortunes of two small wading bird species breeding in the UK. Little Ringed Plover first bred in the UK in Hertfordshire in 1938. Breeding numbers have increased steadily since, accompanied by a range expansion to the north and west. The species is Green-listed in the UK Birds of Conservation Concern. The Ringed Plover, by contrast, is on the UK Birds of Conservation Concern Red list. Both species were surveyed in 1984, and again in 2007. The new study estimated that the number of Little Ringed Plover breeding in the UK had risen by 71% between 1984 and 2007, to 1,239 pairs. The species’ core range remained in England, although breeding pairs have spread further into Wales, northern England and south and east Scotland. Gravel and sand pits were the favoured habitat for Little Ringed Plover, but its relative importance had declined compared to 1984. The species’ use of shingle habitat had grown, following range expansion into northern and western regions. Over the same time period, the breeding population of Ringed Plover in the UK was estimated to have fallen by 37%, to 5,438 pairs. The greatest declines were reported in England and Scotland, with numbers more stable in Wales, Northern Ireland and the Isle of Man. Decreases were marked in both coastal and inland areas, including at sites where Little Ringed Plover numbers had increased. The two species have similar inland habitat preferences, so the reasons underlying the different trends are not clear. Potential factors contributing to the decline in Ringed Plover at coastal sites include disturbance from human recreational activities as well as habitat change elsewhere. Although the UK populations of both species appear have stabilised recently, greater conservation and protection efforts are required at coastal sites to ensure local breeding numbers are prevented from dropping further.