Predation, parasitism, and drought counteract the benefits of patch-burn grazing for the reproductive success of grassland songbirds
Predation, parasitism, and drought counteract the benefits of patch-burn grazing for the reproductive success of grassland songbirds
复制标题
DOI：
10.1093/ornithapp/duab066
复制
发表时间：
2022-05-06
影响因子：
2.4
通讯作者：
Sandercock，Brett K.
中科院分区：
文献类型：
--
作者：
Verheijen，Bram H. F.;Erickson，Amy N.;Sandercock，Brett K.
畜牧业生产的集约化减少了管理的草原植被结构的异质性，这与整个北美草原鸣禽种群的普遍下降有关。斑烧放牧管理的目的是恢复植被结构的异质性，通过燃烧离散的牧场部分，使牛优先在最近被烧毁的地区吃草。虽然斑烧放牧可以增加草原鸣禽的繁殖成功率，我们知道的很少可能与区域变化的捕食者社区或育雏寄生虫丰度，或每年的气候条件变化的相互作用。利用美国堪萨斯东部两个高草草原试验点6年的数据，我们测试了斑烧放牧对三种常见草原鸣禽Dickcissels的育雏寄生率、窝卵数、巢存活率和雏鸟成功率的影响（Spiza americana），Eastern Meadowlark（Sturnella magna）和蚱蜢麻雀（Grasshopper Sparrows）（Ammodramus savannarum），其中牧场管理与补丁燃烧放牧与牧场，每年烧毁，放牧或未放牧。在每年焚烧和未放牧的牧场中，Dickcissel巢的寄生率较低（72.8 ± 4.6% SE vs. 89.1 ± 2.2%），东部草地百灵的巢存活率较高（63.2 ± 20.5% vs. 16.5 ± 3.5%）。然而，平均数量的主机雏鸟每次筑巢尝试没有不同的管理治疗的任何物种。气候条件的年变化对植被结构有很大的影响，但对繁殖成功率没有影响。育雏寄生的概率是一贯高（25.5 - 84.7%）和巢存活率是一贯低（9.9-16.9%）的所有物种汇集在治疗，网站，和年，表明捕食，寄生和干旱的综合影响可以抵消潜在的好处补丁烧放牧管理以前发现在高草草原。虽然管理治疗之间的生殖成功的差异是最小的，补丁燃烧放牧管理仍然有利于草原鸣禽的人口动态的地区，巢捕食者和育雏寄生虫是当地丰富的鸟类提供合适的筑巢栖息地，需要更大量的植被覆盖和凋落物，一般不存在于燃烧的牧场。
Intensification of livestock production has reduced heterogeneity in vegetative structure in managed grasslands, which has been linked to widespread declines in grassland songbird populations throughout North America. Patch-burn grazing management aims to restore some of that heterogeneity in vegetative structure by burning discrete pasture sections, so that cattle preferentially graze in recently burned areas. Although patch-burn grazing can increase reproductive success of grassland songbirds, we know little about possible interactions with regional variation in predator communities or brood parasite abundance, or annual variation in weather conditions. Using six years of data from two tallgrass prairie sites in eastern Kansas, USA, we tested effects of patch-burn grazing on the rates of brood parasitism, clutch size, nest survival, and fledging success of three common grassland songbirds, Dickcissels (Spiza americana), Eastern Meadowlarks (Sturnella magna), and Grasshopper Sparrows (Ammodramus savannarum), among pastures managed with patch-burn grazing versus pastures that were annually burned and either grazed or ungrazed. Dickcissel nests experienced lower parasitism (72.8 ± 4.6% SE vs. 89.1 ± 2.2%) and Eastern Meadowlarks had higher nest survival (63.2 ± 20.5% vs. 16.5 ± 3.5%) in annually burned and ungrazed pastures than pastures managed with patch-burn grazing. However, average number of host fledglings per nesting attempt did not differ among management treatments for any species. Annual variation in weather conditions had a large effect on vegetation structure, but not on reproductive success. Probability of brood parasitism was consistently high (25.5‒84.7%) and nest survival was consistently low (9.9–16.9%) for all species pooled across treatments, sites, and years, indicating that combined effects of predation, parasitism and drought can offset potential benefits of patch-burn grazing management previously found in tallgrass prairies. Although differences in reproductive success among management treatments were minimal, patch-burn grazing management could still benefit population dynamics of grassland songbirds in areas where nest predators and brood parasites are locally abundant by providing suitable nesting habitat for bird species that require greater amounts of vegetation cover and litter, generally not present in burned pastures.