Habitat suitability models (HSM) based on remotely sensed data are useful tools in conservation work. However, they typically use species occurrence data rather than robust demographic variables, and their predictive power is rarely evaluated. These shortcomings can result in misleading guidance for conservation. Here, we develop and evaluate a HSM based on correlates of long term breeding success of an open nest building boreal forest bird, the Siberian jay. In our study site in northern Sweden, nest failure of this permanent resident species is driven mainly by visually hunting corvids that are associated with human settlements. Parents rely on understory nesting cover as protection against these predators. Accordingly, our HSM includes a light detection and ranging (LiDAR) based metric of understory density around the nest and the distance of the nest to the closest settlement to predict breeding success. It reveals that a high understory density 15-80 m around nests is associated with increased breeding success in territories close to settlements (<1.5 km). Farther away from human settlements breeding success is highest at nest sites with a more open understory providing a favourable warmer microclimate. We validated this HSM by comparing the predicted breeding success with landscape-wide census data on Siberian jay occurrence. The correlation between breeding success and occurrence was strong up to 40 km around the study site. However, the HSM appears to overestimate breeding success in regions with a milder climate, and therefore higher corvid numbers. Our findings suggest that maintaining patches of small diameter trees may provide a cost-effective way to restore the breeding habitat for Siberian jays up to 1.5 km from human settlements. This distance is expected to increase in the warmer, southern, and coastal range of the Siberian jay where the presence of other corvids is to a lesser extent restricted to settlements.

Foraging strategies of birds can influence trophic plant-insect networks with impacts on primary plant production. Recent experiments show that some forest insectivorous birds can use herbivore induced plant volatiles (HIPVs) to locate herbivore-infested trees, but it is unclear how birds combine or prioritise visual and olfactory information when making foraging decisions. Here we investigated attraction of ground-foraging birds to HIPVs and visible prey in short vegetation on farmland in a series of foraging choice experiments. Birds showed an initial preference for HIPVs when visual information was the same for all choice options (i.e. one experimental setup had all options with visible prey, another setup with hidden prey). However, if the alternatives within an experimental setup included visible prey (without HIPV) in competition with HIPV-only, then birds preferred the visual option over HIPVs. Our results show that olfactory cues can play an important role in birds’ foraging choices when visual information contains little variation; however, visual cues are preferred when variation is present. This suggests certain aspects of bird foraging decisions in agricultural habitats are mediated by olfactory interaction mechanisms between birds and plants. We also found that birds from variety of dietary food guilds were attracted to HIPVs; hence, the ability of birds to use plant cues is probably more general than previously thought, and may influence the biological pest control potential of birds on farmland.

1. In Europe, agri-environmental schemes (AES) have been unsuccessful in halting biodiversity declines to any great extent. Two particular shortcomings of AES include the low farm uptake and the modest efficacy of many AES options. Partly in response to these shortcomings, initiatives encouraging farmers to take an active role in biodiversity conservation have gained in popularity. However, almost no evaluations of such initiatives exist. 2. We evaluated uptake of conservation advice on farms in the Swedish Volunteer & Farmer Alliance, a BirdLife Sweden-coordinated project aimed at farmland bird conservation, and the response of farmland birds to those actions using farm-level survey data, in a before-after implementation assessment. 3. Uptake was higher for unsubsidised (i.e. non-AES) measures than for AES options, and depended on farmers’ interest in nature, farm size (higher uptake on larger farms) and production type (higher on organic farms). 4. In general, abundances of non-crop nesting and field-nesting bird species declined between inventory years (median interval 3 years). Decreases were more marked in agriculturally marginal regions than in more arable-dominated regions, and declines were stronger on organic than conventional farms. 5. Negative abundance trends among non-crop nesting species were reduced by an increasing number of conservation measures at the farm, but only in the more arable-dominated landscapes. Changes in other non-crop species and in field-nesting species did not significantly relate to implemented measures, but the power to detect such effects was generally small due to the small sample size of high-uptake farms as well as high inter-farm variability. 6. Implications: Our results suggest that Volunteer Farmer Alliances and the addition of unsubsidised measures may be successful in changing the local number of non-crop nesting farmland birds at the farm level, and especially so in intensively managed agricultural landscapes. Thus, unsubsidised measures can be a useful addition to the set of agri-environment tools, although their effects on breeding bird numbers are (as with AES) dependent on landscape context, as well as on ensuring high on-farm uptake of different interventions.

Crop diversification has been introduced as an environmental strategy in the ‘Greening’ of the EU Common Agricultural Policy (CAP) for 2015–2020. The primary target of crop diversification is soil and ecosystem resilience, but claims for potential benefits for farmland biodiversity are also common. However, understanding of relationships between the number (compositional heterogeneity) and spatial arrangement (configurational heterogeneity) of crop fields and biodiversity is generally poor, making such claims relatively unfounded. In this study, we monitored crop and farmland bird diversity on 178 farms across Sweden's main agricultural areas. From a pre-implementation assessment, we show that >97% of the assessed farms would not be required to change their management under the CAP crop diversification measure (minimum of three crops for farms with 30+ ha), suggesting that this measure has generated little change on Swedish farms. While accounting for non-crop elements and farming system (conventional or organic), we show that crop structural diversity (i.e. the management and vegetation structure of crops) rather than crop diversity senso lato positively affected richness of non-crop breeding bird species with stronger effects in arable, compared with forest-dominated landscapes. No such effects were observed among field-nesting farmland bird species. Organic farming had little influence on farmland birds with positive effects only in the most arable-dominated landscapes and for field-nesting species only. In forest-dominated landscapes, organic farms even held lower field-nester densities compared with conventional farms, possibly due to the dominance of grasslands on organic farms that in these landscapes support lower densities of field-nesting species compared with cereals. Policy implications. Our study illustrates the importance of a consideration of structural instead of species diversity of crops for biodiversity, in this case farmland birds. We also underline the absence of such a distinction in current EU Common Agricultural Policy Greening, while simultaneously setting levels on crop diversification too low resulting in little to no change in landscape-scale crop diversity on Swedish farmland. We recommend that future efforts to manage farmland biodiversity should include ways of increasing the structural diversity of crops at the scale of farms and landscapes.

Adverse weather conditions during parental care may have direct consequences for offspring production, but longer-term effects on juvenile and parental survival are less well known. We used long-term data on reproductive output, recruitment, and parental survival in northern wheatears (Oenanthe oenanthe) to investigate the effects of rainfall during parental care on fledging success, recruitment success (juvenile survival), and parental survival, and how these effects related to nestling age, breeding time, habitat quality, and parental nest visitation rates. While accounting for effects of temperature, fledging success was negatively related to rainfall (days > 10 mm) in the second half of the nestling period, with the magnitude of this effect being greater for breeding attempts early in the season. Recruitment success was, however, more sensitive to the number of rain days in the first half of the nestling period. Rainfall effects on parental survival differed between the sexes; males were more sensitive to rain during the nestling period than females. We demonstrate a probable mechanism driving the rainfall effects on reproductive output: Parental nest visitation rates decline with increasing amounts of daily rainfall, with this effect becoming stronger after consecutive rain days. Our study shows that rain during the nestling stage not only relates to fledging success but also has longer-term effects on recruitment and subsequent parental survival. Thus, if we want to understand or predict population responses to future climate change, we need to consider the potential impacts of changing rainfall patterns in addition to temperature, and how these will affect target species' vital rates.