Agri-environmental measures aim at mitigating the negative impacts of modern agriculture on farmland biodiversity. For example, soil management practices can positively influence the abundance and diversity of songbirds in olive groves by enhancing habitat and food availability. However, little is known about their potential implications on the breeding success of these species. We monitored nest density and breeding performance of tree-nesting birds in 17 olive groves of southern Spain under two contrasting soil management regimes (with and without herbaceous cover) over three years. We analyzed breeding success by examining the transitions between different stages of the breeding cycle for three common cardueline finches: Common Linnet (Linaria cannabina), European Greenfinch (Chloris chloris), and European Serin (Serinus serinus). Breeding success of songbirds was low (19% of 88 nests for L. cannabina, 16% of 196 nests for C. chloris, and 38% of 234 nests for S. serinus). Many nests were abandoned prior to egg laying and nesting failure was highest between egg laying and hatching. Nest predation (56.6%) was the main cause of nest loss. Although soil management regimes did not influence breeding success, the presence of herbaceous cover had opposing effects on nest densities of the three species: groves with herbaceous cover had higher nest densities for greenfinches, lower for serins, and this treatment had no effect on Common Linnet. Other factors, like disturbances due to management activities or interannual weather variation may have a larger impact on nesting success than soil management regimes, at least for some species and for specific stages of their breeding cycle. The fact that nest densities of some birds were negatively affected by soil treatments associated with agri-environmental actions aimed at benefiting biodiversity raises the question of the general applicability of these measures for conservation.

中文翻译：

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橄榄树的土壤管理对筑巢雀形目鸟类的巢穴密度和繁殖成功率有不同的影响

农业环境措施旨在减轻现代农业对农田生物多样性的负面影响。例如，土壤管理实践可以通过提高栖息地和食物供应量来积极影响橄榄树林中鸣禽的丰度和多样性。然而，人们对它们对这些物种繁殖成功的潜在影响知之甚少。我们在三年内监测了西班牙南部 17 个橄榄树林中在两种不同的土壤管理制度（有和没有草本覆盖）下筑巢鸟类的巢密度和繁殖性能。我们通过检查三种常见红雀（Linaria cannabina）、欧洲绿雀（Chloris chloris）和欧洲丝氨酸（Serinus serinus）的育种周期不同阶段之间的过渡来分析育种成功。鸣禽的繁殖成功率很低（L. cannabina 的 88 个巢穴中的 19%，C. chloris 的 196 个巢穴中的 16%，S. serinus 的 234 个巢穴中的 38%）。许多巢穴在产卵前被遗弃，产卵和孵化之间的筑巢失败率最高。巢穴捕食（56.6%）是巢穴丢失的主要原因。尽管土壤管理制度不影响繁殖成功，但草本覆盖的存在对三个物种的巢密度有相反的影响：有草本覆盖的树林中绿翅雀的巢密度较高，丝氨酸较低，这种处理对普通红雀没有影响. 其他因素，例如由于管理活动或年际天气变化引起的干扰，可能比土壤管理制度对筑巢成功的影响更大，至少对于某些物种及其繁殖周期的特定阶段而言。