Ecological interactions between native species are often disturbed by invasive species. However, to understand their impact on wild native animal populations on a country scale it is necessary to develop a predictive model. Therefore, I followed the species density distribution modelling approach to explore how feral domestic cats (Felis catus) along with environmental predictors determined densities of two bird species, the Yellowhammer (Emberiza citrinella) and the Yellow Wagtail (Motacilla flava) on the whole area of Poland. As a modelling method, I used the Generalised Additive Model to develop two models for each of the two bird species: The first with the feral cat density as an additional predictor, and the second without it. As a result, I demonstrated the negative impact of cat density on native bird populations, illustrated by reduced density of the two studied species in their preferred habitats, in which cats reached a high density. Although it cannot be explicitly asserted that cats lead to a local extinction of the two bird species, these predators should not be underestimated. In many locations feral populations are fed with new individuals, and they do not follow the same internal mechanisms regulating their population as the native bird fauna. Thus, on a large spatial scale species density distribution models of birds should include cats’ population size as an additional predictor when this predator's environmental preferences overlap with preferences of the studied target groups.

本地物种之间的生态相互作用经常受到入侵物种的干扰。然而，要了解它们在国家范围内对野生本地动物种群的影响，有必要开发一个预测模型。因此，我遵循物种密度分布建模方法来探索野生家猫 ( Felis catus ) 以及环境预测因子如何确定黄锤 ( Emberiza citrinella ) 和黄鹡鸰 ( Motacilla flava )两种鸟类的密度) 在整个波兰地区。作为一种建模方法，我使用广义加性模型为两种鸟类中的每一种开发了两个模型：第一个将野猫密度作为额外的预测因子，第二个没有它。结果，我证明了猫密度对本地鸟类种群的负面影响，这可以通过两个研究物种在其首选栖息地的密度降低来说明，其中猫达到了高密度。虽然不能明确断言猫会导致这两种鸟类在当地灭绝，但不应低估这些捕食者。在许多地方，野生种群以新个体为食，它们不遵循与本地鸟类动物群相同的内部机制来调节种群。因此，