Data from: Effect of haemosporidian infections on host survival and recapture rate in the blue tit

Parasites are ubiquitous in the wild and by imposing fitness costs on their hosts they constitute an important selection factor. One of the most common parasites of wild birds are Plasmodium and Haemoproteus, protozoans inhabiting the blood, which cause avian malaria and malaria-like disease, respectively. Although they are expected to cause negative effects in infected individuals, in many cases studies in natural populations failed to detect such effect. Using data from seven breeding seasons (2008 - 2014), we applied a multistate capture – mark – recapture approach to study the effect of infection with malaria and malaria-like parasites, individual age and sex on the probability of survival and recapture rate in a small passerine, the blue tit (Cyanistes caeruleus), inhabiting the island of Gotland, Sweden. We found no effect of infection on survival prospects. However, the recapture rate of infected individuals was higher than that of uninfected ones. Thus, while our data do not support the presence of infection costs in terms of host survival, it suggests that parasites from the genera Plasmodium and Haemoproteus may affect some aspects of host behaviour, which translates into biased estimation of infection frequency at the population level.

寄生虫广泛分布于野外环境中，通过对宿主施加适合度代价，成为重要的选择压力因素。野生鸟类最常见的寄生虫之一为疟原虫属（Plasmodium）与血变虫属（Haemoproteus），二者均为寄生于血液的原生动物，分别引发禽疟疾与类疟疾疾病。尽管这类寄生虫被认为会对感染个体产生负面影响，但诸多针对自然种群的研究均未能检测到此类效应。本研究依托2008至2014年共7个繁殖季的调查数据，采用多状态捕获-标记-重捕法（multistate capture-mark-recapture），针对栖息于瑞典哥得兰岛的小型雀形目鸟类——蓝山雀（Cyanistes caeruleus），分析了疟疾及类疟疾寄生虫感染、个体年龄与性别对其存活概率与重捕率的影响。研究结果显示，寄生虫感染对蓝山雀的存活前景并无显著影响。但感染个体的重捕率显著高于未感染个体。因此，尽管本研究数据不支持“寄生虫感染会对宿主存活产生代价”这一结论，但结果表明，疟原虫属与血变虫属的寄生虫可能会影响宿主的部分行为特征，进而导致种群水平上的感染频率估算出现偏差。