Marzluff John M, DeLap Jack H, Oleyar M David, Whittaker Kara A, Gardner Beth
School of Environmental and Forest Sciences, University of Washington, Seattle, Washington, United States of America.
PLoS One. 2016 Dec 28;11(12):e0167829. doi: 10.1371/journal.pone.0167829. eCollection 2016.
Changes in land cover during urbanization profoundly affect the diversity of bird communities, but the demographic mechanisms affecting diversity are poorly known. We advance such understanding by documenting how urbanization influences breeding dispersal-the annual movement of territorial adults-of six songbird species in the Seattle, WA, USA metropolitan area. We color-banded adults and mapped the centers of their annual breeding activities from 2000-2010 to obtain 504 consecutive movements by 337 adults. By comparing movements, annual reproduction, and mate fidelity among 10 developed, 5 reserved, and 11 changing (areas cleared and developed during our study) landscapes, we determined that adaptive breeding dispersal of sensitive forest species (Swainson's Thrush and Pacific wren), which involves shifting territory and mate after reproductive failure, was constrained by development. In changing lands, sensitive forest specialists dispersed from active development to nearby forested areas, but in so doing suffered low annual reproduction. Species tolerant of suburban lands (song sparrow, spotted towhee, dark-eyed junco, and Bewick's wren) dispersed adaptively in changing landscapes. Site fidelity ranged from 0% (Pacific wren in changing landscape) to 83% (Bewick's wren in forest reserve). Mate fidelity ranged from 25% (dark-eyed junco) to 100% (Bewick's wren). Variation in fidelity to mate and territory was consistent with theories positing an influence of territory quality, asynchronous return from migration, prior productivity, and reproductive benefits of retaining a familiar territory. Costly breeding dispersal, as well as reduced reproductive success and lowered survival cause some birds to decline in the face of urbanization. In contrast, the ability of species that utilize edges and early successional habitats to breed successfully, disperse to improve reproductive success after failure, and survive throughout the urban ecosystem enables them to maintain or increase population size.
城市化过程中土地覆盖的变化深刻影响着鸟类群落的多样性，但影响多样性的人口统计学机制却鲜为人知。我们通过记录城市化如何影响美国华盛顿州西雅图市大都市区六种鸣禽的繁殖扩散（即领地成年鸟的年度移动），来推进这方面的认识。我们给成年鸟戴上彩色环志，并绘制它们在2000年至2010年期间年度繁殖活动的中心位置，以获取337只成年鸟的504次连续移动数据。通过比较10个已开发、5个保留和11个变化区域（在我们研究期间被清理和开发的区域）景观中的移动、年度繁殖和配偶忠诚度，我们确定敏感森林物种（斯温森氏夜鸫和太平洋鹪鹩）的适应性繁殖扩散，即在繁殖失败后转移领地和配偶，受到了开发的限制。在变化的土地上，敏感森林专家从活跃开发区扩散到附近的森林地区，但这样做的结果是年度繁殖率较低。适应郊区土地的物种（歌雀、斑点唧鹀、暗眼灯草鹀和比威克氏鹪鹩）在变化的景观中进行适应性扩散。地点忠诚度从0%（变化景观中的太平洋鹪鹩）到83%（森林保护区中的比威克氏鹪鹩）不等。配偶忠诚度从25%（暗眼灯草鹀）到100%（比威克氏鹪鹩）不等。对配偶和领地的忠诚度变化与一些理论相符，这些理论认为领地质量、迁徙异步返回、先前的生产力以及保留熟悉领地的繁殖益处会产生影响。代价高昂的繁殖扩散，以及繁殖成功率降低和存活率下降，导致一些鸟类在城市化面前数量减少。相比之下，利用边缘和早期演替栖息地成功繁殖、在繁殖失败后扩散以提高繁殖成功率并在整个城市生态系统中生存的物种，能够维持或增加种群数量。
