Branoff Benjamin L, Campos-Cerqueira Marconi
Gulf Ecosystem Measurement and Modeling Division, Office of Research and Development, United States Environmental Protection Agency, Gulf Breeze, FL, United States.
Rainforest Connection, San Francisco, CA, United States.
Front Mar Sci. 2021 Jul 22;8. doi: 10.3389/fmars.2021.670288.
The mangroves of Puerto Rico occupy a gradient of urbanization that offers a chance to test hypotheses on urban faunal communities. These hypotheses state that urban avifaunal communities have greater representation by generalists and that certain mangrove specialists can utilize urban landscapes. Much of this is said to be driven by food resources, with frugivores and nectarivores benefiting from abundant residential flowers and fruits, while insectivores are driven away by low food resources. This study used passive acoustic monitoring to identify the audible anuran and avifaunal species in mangroves across an urban gradient of Puerto Rico. Five anurans and thirty-one avian species were detected across all sites, with twenty-three species found at the most species rich site, and eight at the least rich site. Analyses on urban effects were conducted at an island-wide scale as well as a local scale with different results between the two. Island wide, the most urban faunal communities were more similar to each other in species composition relative to the least urban communities, and there was a significant difference in the community composition between the two. However, there were no differences in avian or anuran species richness between the least and most urban sites. Minimum canopy height was the strongest predictor of overall avian richness and avian invertivore richness, while the extent of mixed forest cover was the strongest predictor for increasing anuran richness. Some urban metrics, such as street density and the percent of surrounding urban and developed open space were strong predictors of certain avian feeding guilds and distribution groups. At the local scale, sites of maximum urbanness held 2-3 more bird species on average than corresponding sites of minimum urbanness at the same location, although there was no difference in anuran species and no differences in avian or anuran community composition between the two. Further, avian richness did increase significantly from the minimum to maximum urbanness site at six of the nine locations. These findings highlight that higher mangrove canopies are the strongest predictor of higher avian richness, but depending on the scale of observations, urbanness also plays a limited role in shaping mangrove faunal communities.
波多黎各的红树林分布在一个城市化梯度带上，这为检验关于城市动物群落的假说提供了机会。这些假说指出，城市鸟类群落中泛化种的占比更大，并且某些红树林特化种能够利用城市景观。据说这很大程度上是由食物资源驱动的，食果动物和食蜜动物受益于丰富的居民区花卉和果实，而食虫动物则因食物资源匮乏而被驱赶。本研究使用被动声学监测来识别波多黎各城市梯度带上红树林中可听到的无尾目和鸟类物种。在所有地点共检测到5种无尾目动物和31种鸟类，物种最丰富的地点发现了23种，最不丰富的地点发现了8种。在全岛范围以及局部尺度上对城市影响进行了分析，两者结果不同。在全岛范围内，城市化程度最高的动物群落彼此之间在物种组成上比城市化程度最低的群落更为相似，且两者在群落组成上存在显著差异。然而，城市化程度最低和最高的地点之间，鸟类或无尾目物种丰富度没有差异。最低树冠高度是总体鸟类丰富度和鸟类食虫动物丰富度的最强预测因子，而混交林覆盖范围是增加无尾目丰富度的最强预测因子。一些城市指标，如街道密度以及周围城市和已开发开放空间的百分比，是某些鸟类觅食类群和分布群体的强预测因子。在局部尺度上，城市化程度最高的地点平均比同一位置城市化程度最低的相应地点多2 - 3种鸟类，尽管无尾目物种没有差异，且两者在鸟类或无尾目群落组成上也没有差异。此外，在九个地点中的六个地点，鸟类丰富度从城市化程度最低的地点到最高的地点确实显著增加。这些发现突出表明，较高的红树林树冠是较高鸟类丰富度的最强预测因子，但根据观测尺度的不同，城市化在塑造红树林动物群落方面也发挥着有限的作用。
