Heyer Eileen, Cimadom Arno, Wappl Christian, Tebbich Sabine
Department of Behavioural Biology University of Vienna Althanstraße 14 1090 Vienna Austria.
Ibis (Lond 1859). 2021 Jan;163(1):137-149. doi: 10.1111/ibi.12845. Epub 2020 May 27.
The parental food compensation hypothesis suggests that parents may compensate for the negative effects of parasites on chicks by increased food provisioning. However, this ability differs widely among host species and may also depend on ecological factors such as adverse weather conditions and habitat quality. Although weed management can improve habitat quality, management measures can bring about a temporary decrease in food availability and thus may reduce parents' ability to provide their nestlings with enough energy. In our study we investigated the interaction of parasitism and weed management, and the influence of climate on feeding rates in a Darwin's tree finch species, which is negatively impacted by two invasive species. The larvae of the invasive parasitic fly ingest the blood and body tissues of tree finch nestlings, and the invasive Blackberry affects one of the main habitats of Darwin's tree finches. We compared parental food provisioning of the Small Tree Finch in parasitized and parasite-free nests in three different areas, which differed in invasive weed management (no management, short-term and long-term management). In a parasite reduction experiment, we investigated whether the Small Tree Finch increases food provisioning rates to nestlings when parasitized and whether this ability depends on weed management conditions and precipitation. Our results provide no evidence that Small Tree Finches can compensate with additional food provisioning when parasitized with . However, we found an increase in male effort in the short-term management area, which might indicate that males compensate for lower food quality with increased provisioning effort. Furthermore, parental food provisioning was lower during rainfall, which provides an explanation for the negative influence of rain on breeding success found in earlier studies. Like other Darwin's finches, the Small Tree Finch seems to lack the ability to compensate for the negative effects of parasitism, which is one explanation for why this invasive parasite has such a devastating effect on this host species.
亲代食物补偿假说认为，亲代可能会通过增加食物供应来弥补寄生虫对雏鸟的负面影响。然而，这种能力在宿主物种之间差异很大，也可能取决于生态因素，如恶劣天气条件和栖息地质量。虽然杂草管理可以改善栖息地质量，但管理措施可能会导致食物供应量暂时减少，从而可能降低亲代为雏鸟提供足够能量的能力。在我们的研究中，我们调查了寄生与杂草管理的相互作用，以及气候对达尔文树雀喂食率的影响，这种树雀受到两种入侵物种的负面影响。入侵寄生蝇的幼虫会摄取树雀雏鸟的血液和身体组织，而入侵的黑莓会影响达尔文树雀的主要栖息地之一。我们比较了三个不同区域中，受寄生虫感染的巢穴和未受寄生虫感染的巢穴中，小树雀亲代的食物供应情况，这三个区域的入侵杂草管理情况不同（无管理、短期管理和长期管理）。在一项减少寄生虫的实验中，我们研究了小树雀在受寄生虫感染时是否会提高对雏鸟的食物供应率，以及这种能力是否取决于杂草管理条件和降水量。我们的结果没有提供证据表明，小树雀在感染寄生虫时能够通过额外的食物供应来进行补偿。然而，我们发现短期管理区域内雄性的努力增加了，这可能表明雄性通过增加供应努力来弥补较低的食物质量。此外，降雨期间亲代的食物供应较低，这为早期研究中发现的降雨对繁殖成功率的负面影响提供了解释。和其他达尔文雀一样，小树雀似乎缺乏补偿寄生虫感染负面影响的能力，这也是为什么这种入侵寄生虫对这种宿主物种具有如此毁灭性影响的一个原因。
