Corra Joseph, Sullivan S Mažeika P
Office of Research and Development, U.S. Environmental Protection Agency, 26 Martin Luther King Dr., Cincinnati, OH 45268, USA.
School of Environment and Natural Resources, The Ohio State University, 125 Heffner Bldg 352 W. Dodridge St., Columbus, OH 43202, USA.
Conserv Physiol. 2021 Oct 25;9(1):coab084. doi: 10.1093/conphys/coab084. eCollection 2021.
Aerial insectivorous bird populations have declined precipitously in both North America and Europe. We assessed the effects of insect prey availability, climate and shifts in water quality associated with urbanization on haematocrit, haemoglobin concentration and heterophil-lymphocyte (H/L) ratios among ~13-day-old tree swallow () nestlings in the Columbus, Ohio area. Higher mean temperature and increased frequency of extreme heat days during the early breeding period (May-June) were linked to reduced nestling physiological condition as evidenced by lower concentrations of haemoglobin and haematocrit, potentially due to increased heat stress, shifts in insect prey availability or altered parental provisioning efforts. Urbanization and the size and density of emergent aquatic insects were associated with elevated physiological stress, whereas higher mean temperatures and terrestrial insect size were related to lower stress as measured by H/L ratios. Overall, these findings highlight the complex environmental conditions driving nestling health, which may be indicative of post-fledging survival and, consequently, population growth. Our results underscore the need for conservation approaches that adequately address the interrelated effects of changes in climate, land use and food resources on aerial insectivorous birds.
在北美和欧洲，食虫鸟类的数量都急剧下降。我们评估了昆虫猎物可获得性、气候以及与城市化相关的水质变化对俄亥俄州哥伦布市地区约13日龄树燕（）雏鸟的血细胞比容、血红蛋白浓度和异嗜性粒细胞与淋巴细胞（H/L）比率的影响。繁殖初期（5月至6月）较高的平均温度和极端炎热天数的增加与雏鸟生理状况下降有关，表现为血红蛋白和血细胞比容浓度较低，这可能是由于热应激增加、昆虫猎物可获得性的变化或亲代育雏努力的改变。城市化以及水生昆虫的大小和密度与生理应激升高有关，而较高的平均温度和陆生昆虫大小与较低的应激有关（通过H/L比率衡量）。总体而言，这些发现突出了驱动雏鸟健康的复杂环境条件，这可能预示着出飞后的存活率，进而影响种群增长。我们的结果强调了采取保护措施的必要性，这些措施要充分应对气候、土地利用和食物资源变化对食虫鸟类的相互关联影响。
