森林-草原交错带夏季鸟类群落多样性特征

2004～2006年夏季利用样线法研究了内蒙古高原东南缘森林-草原交错带鸟类群落多样性特征及变化规律.共记录鸟类73种,隶属于13目28科56属,鸟类区系具有明显的古北界特征.鸟类群落物种数和密度年间差异不显著,α多样性随森林-草原交错带环境梯度变化而发生显著变化:在不同植被地带之间,物种数、密度、Shannon-Wiener指数和Pielou指数差异极显著、但科-属多样性差异不显著,鸟类群落α多样性各项指数表现为森林带＜交错带森林草甸区＞交错带草甸草原区＞草原带的特征与变化趋势(DG-F为交错带草甸草原区＞森林带);其中,森林草甸区是鸟类物种多样性的显著增长区,具有最高的物种数和密度,明显体现了交错区的边缘效应,草甸草原区是鸟类向草原过渡的显著变化区域、物种多样性开始显著减少.β多样性随不同植被地带逐级发生显著变化,环境差异最大的森林带-森林草甸区和草甸草原区-草原带具有最高的β多样性,物种替代速率最大;鸟类物种替代速率与环境梯度"陡度"有密切关系.鸟类优势种在各植被地带之间存在较大变化.鸟类群落的物种数、密度和物种多样性(H')与森林斑块数呈显著的正相关性,在大尺度空间上森林斑块数是影响鸟类群落多样性的最主要因素.     

澳门城市栖息地斑块中鸟类群落功能和谱系多样性

了解群落构建过程是生态学的核心和基本问题,这对于解释物种共存和物种多样性的维持,完善生物多样性保护政策至关重要。与传统的物种多样性相比,功能和谱系多样性能够提供更多的信息,特别是在群落构建过程方面提供深刻见解。2014年5月—2017年1月,采用样线法对澳门地区5个城市栖息地斑块中(生态一区、鹭鸟林、赛马场滩涂、关闸口岸滩涂和莲花桥侧红树林)的鸟类进行繁殖季和越冬季的调查,共调查14次。利用鸟类丰富度和多度来表征群落的物种多样性,其中多度以最大值保留法计;功能和谱系多样性分别采用功能丰富度(functional richness:FRic)和Faith'PD。同时,利用基于多度加权的平均成对功能距离(mean pairwise functional distance,MFD)和平均成对谱系距离(mean pairwise phylogenetic distance,MPD)来表征群落的功能和谱系结构。结果表明:共记录98种鸟类,隶属于14目32科,目、科、种中数量最多的依次为,雀形目鸟类最多为47种,鹭科物种数为11种,白鹭多度为849只;鸟类物种丰富度(68种)和PD在生态一区最高,多度在莲花桥侧红树林最高为2940只,MFD和FRic在赛马场滩涂最高,MPD在生态一区最高;斑块面积在鸟类丰富度、多度、FRic和PD中具有普遍重要性,植被面积和滩涂面积则分别强烈影响着MFD和MPD;关闸口岸滩涂和莲花桥侧红树林的鸟类群落SES.MFD显著低于随机值(P 0. 05),鹭鸟林和赛马场滩涂的鸟类群落SES. MPD显著低于随机值(P0.05),表明关闸口岸滩涂和莲花桥侧红树林鸟类群落功能聚集(functional clustering),可能与生境过滤驱动群落构建有关。栖息地斑块的特征差异导致了鸟类群落构建机制的不同,这是仅仅考虑物种多样性难以提供的信息,说明了研究群落构建机制时考虑多维度多样性的必要性。     

广西弄岗国家级自然保护区喀斯特森林鸟类群落结构与多样性分析

弄岗国家级自然保护区森林是典型的喀斯特森林。2010年2月—2013年2月对其中的鸟类群落进行了研究。利用样线法、样点法和数理统计等方法对弄岗森林鸟类群落结构、多样性等进行了调查和数据分析。结果如下:(1)共记录到鸟类222种,隶属13目42科。其中留鸟148种,夏候鸟31种,冬候鸟39种,旅鸟4种。弄岗喀斯特森林鸟类群落的特点为留鸟所占比例远大于候鸟,雀形目构成鸟类群落的主要组成成分。弄岗喀斯特森林鸟类区系组成在华中、华南、西南这三区广泛分布的种类最多,鸟类的区系组成具有一定的华南、华中、西南三区区系特征,但总体上以华南区区系特征为主。(2)对弄岗喀斯特森林林缘、弃耕地、森林内部3种生境进行多样性研究。3种生境的夏季和冬季鸟类多样性指数、均匀性指数和优势度指数均较高。鸟类群落结构组成在夏冬两季的波动并不明显,总体上较为稳定。     

澳门生态一区和二区水鸟谱系多样性的季节变化

季节变化是鸟类群落的重要特征之一,其引起的环境变化决定着鸟类群落构建过程中不同驱动因子的作用力。因此,了解鸟类群落结构的季节变化,对于全面认识生物群落结构具有重要意义,尤其利用谱系多样性来探讨鸟类的季节性变化和推断群落聚集规律越来越受到关注。2018年1—12月,采用样线法对澳门生态一区和二区2块湿地进行逐月调查,记录水鸟的物种丰富度和多度,并分析水鸟谱系多样性的季节动态。结果显示,1)共记录水鸟37种,隶属于6目9科,目、科、种中数量最多的依次为:鸻形目Charadriiformes物种数为15种,鹭科Ardeidae物种数为11种,白鹭Egretta garzetta多度为540只。2)生态一区和二区水鸟的物种丰富度在冬季最高,其次为秋季;生态一区和二区的物种多度分别在秋季和冬季最高;谱系多样性和平均成对谱系距离的季节变化规律与物种丰富度的相似。3)生态一区和二区的鸟类群落分别在春、秋、冬季和秋季趋向于谱系发散,而在其他时间大多呈现出谱系聚集。谱系发散可能表明了种间竞争在群落构建中作用更大,而谱系聚集则表明了环境过滤对繁殖季水鸟群落构建具有重要作用。结果表明,湿地水鸟群落的驱动因子...     

澳门城市栖息地斑块中鸟类群落功能和谱系多样性

了解群落构建过程是生态学的核心和基本问题,这对于解释物种共存和物种多样性的维持,完善生物多样性保护政策至关重要。与传统的物种多样性相比,功能和谱系多样性能够提供更多的信息,特别是在群落构建过程方面提供深刻见解。2014年5月—2017年1月,采用样线法对澳门地区5个城市栖息地斑块中(生态一区、鹭鸟林、赛马场滩涂、关闸口岸滩涂和莲花桥侧红树林)的鸟类进行繁殖季和越冬季的调查,共调查14次。利用鸟类丰富度和多度来表征群落的物种多样性,其中多度以最大值保留法计;功能和谱系多样性分别采用功能丰富度(functional richness:FRic)和Faith’PD。同时,利用基于多度加权的平均成对功能距离(mean pairwise functional distance,MFD)和平均成对谱系距离(mean pairwise phylogenetic distance,MPD)来表征群落的功能和谱系结构。结果表明:共记录98种鸟类,隶属于14目32科,目、科、种中数量最多的依次为,雀形目鸟类最多为47种,鹭科物种数为11种,白鹭多度为849只;鸟类物种丰富度(68种)和PD在生态一区最高,...     

繁殖期荒漠鸟类群落与自然植被的相关格局

为探讨植被结构和物种组成对鸟类群落多度分布的影响,于2010年5～8月,在阜康地区所涵盖的显域植被梯度带(梭梭、琵琶柴及蒿属荒漠)内分别布设3～4条样线,调查繁殖鸟类群落多度分布及植被参数.借助平均高度和盖度反映植被结构,平均物种数目反映植物组成.从鸟类群落中抽取显著正相关鸟种组合及狭分布鸟种组合,将不同的鸟类组合与植...     

火后恢复时间影响大兴安岭寒温带森林内部与边缘鸟类多样性

中重度火干扰通常会显著改变森林结构与功能,甚至引发森林演替,严重影响鸟类群落组成与多样性。大兴安岭是我国林火高发热点地区之一,但林火对鸟类多样性影响的研究较少,特别是对功能多样性的影响尚不清楚。本研究于2021年7–8月在大兴安岭地区的黑龙江南瓮河国家级自然保护区,采用样点法对森林鸟类展开调查,量化不同林火干扰时间下森林内部和边缘鸟类功能多样性的差异。同时,通过系统性文献检索,进一步比较了大兴安岭地区不同林分组成与鸟类功能多样性的关系。结果发现:(1)不同林火事件后,森林内部鸟类群落的组成差异较小,但边缘鸟类组成差异较大;(2)森林内部的鸟类功能丰富度和均匀度随火后恢复时间增加逐渐升高,并且在火后早期阶段森林边缘的功能丰富度更高;(3)随着火后恢复时间的增加,森林边缘的留鸟比例增加,夏候鸟比例减少;(4)在大兴安岭地区,针阔混交林中的鸟类功能丰富度显著高于兴安落叶松(Larix gmelinii)林。本研究建议在大兴安岭寒温带森林中,保持森林内部结构稳定性,同时提升火后早期阶段森林边缘的植被多样性,这有利于维持鸟类较高的功能丰富度和功能均匀度。     

人为干扰对武汉市城市绿地鸟类群落结构的影响

城市绿地生态系统是城市景观的重要组成部分,具有重要的生态与文化价值。鸟类是城市绿地生态系统的指示类群,研究人类活动对鸟类资源的影响能够为城市生态景观的建设与维护提供重要理论依据。本研究于2021年10月至2022年5月,采用样线法对武汉市不同干扰强度的城市绿地内林鸟群落进行调查。共记录到鸟类11目34科100种,其中国家二级重点保护鸟类9种,在物种组成上以雀形目为主(76种,占调查到总鸟种数的76%),在居留型上以留鸟为主(42种,42%),在区系上主要属于东洋界(45种,45%)。繁殖季鸟类物种数高于非繁殖季,主要是由于夏候鸟和旅鸟的增加导致。在不同干扰强度中,重度干扰斑块的平均鸟类个体数最多,轻度干扰斑块的鸟类物种丰富度、多样性指数和均匀度指数最高,而中度干扰斑块的鸟类个体数、物种丰富度、多样性指数和均匀度指数均为最低,且繁殖季和非繁殖季鸟类群落结构在不同人为干扰强度中的格局未发生变化。综上所述,武汉市城市绿地的鸟类多样性较为丰富,随着干扰强度增加,鸟类多样性出现非线性差异,揭示了人为干扰与自然干扰对生态影响的差异;在面积狭小、破碎化严重的斑块中,人为干扰可能有利于城市绿地鸟类多样性的维持。     

北京西山静福寺地区鸟类多度分布格局

物种多度格局分析对理解群落结构具有重要意义。采用分割线段模型对北京西山静福寺地区鸟类群落物种数量关系进行拟合研究,并运用秩相关性分析对模型进行相关系数检验,结果表明:(1)该地区鸟类群落多度格局模型与分割线段模型显著相关,利用分割线段模型可以良好的拟合该地区鸟类群落多度格局;(2)鸟类多度分布格局具有时间和空间的双重属性;(3)月尺度上,1月与其他月份差异显著,森林群落间差异不显著;(4)季尺度上,冬季与春、秋两季差异显著,落叶阔叶林与针阔混交林差异显著,针叶林与落叶阔叶林、针阔混交林差异都不显著;(5)年尺度上,年变化差异不显著。     

广西山地农业化背景下鸟类多样性比较

随着农业用地需求增加, 生物多样性受到严重威胁并急剧下降。为探讨农业化对鸟类多样性的影响, 本文在2020年10月至2021年10月期间, 对广西大瑶山、大明山、十万大山3个国家级自然保护区以及周边农田区域内鸟类进行了调查。研究选取森林、近地农田(距离森林较近的农田)、远地农田(距离森林较远的农田) 3种生境, 布设样点共计180个, 并在不同季节(春、夏、秋、冬)对鸟类多样性进行了调查。结果如下: (1) 3种生境物种累积曲线呈先快速上升, 后变为渐近线或增速放缓趋势, 各生境实际调查鸟类物种数与预测值比例均大于60%, 表明鸟类调查充分; (2)共记录到鸟类196种, 隶属于14目54科, 其中雀形目鸟类占比最高(71.4%)。不同生境记录到鸟类种数从多到少依次为: 森林(103)、近地(101)、远地(94); (3)相似性分析结果表明, 森林与近地农田和远地农田间鸟类相似性差异都较大, 近地与远地间鸟类群落更为相似; (4) 3种生境鸟类群落Shannon-Wiener多样性指数在不同季节里均表现为: 远地 > 近地 > 森林; (5)广义线性混合模型结果显示, 两种农田生境鸟类多样性显著高于森林, 而近地和远地农田生境间鸟类多样性无显著差异。研究结果表明, 虽然森林鸟类多样性较低, 但对其特有种具有较高的保护作用; 尽管鸟类对农田生境表现出更高的喜好, 但农田内人为干扰较为频繁, 缺乏相关的保护措施, 应加强对农田鸟类的保护。     

Dung beetle assemblages in primary forest and disturbed habitats in a tropical dry forest landscape in western Mexico

Dung beetles (Scarabaeinae) are conspicuous components in most terrestrial ecosystems, performing important ecological functions and services. Being sensitive to several types of disturbance, they have been successfully used as indicators of habitat change. Dung beetle communities in tropical rainforests have been well studied, but considerably less information is available for tropical dry forests. In this study I sampled dung beetles in two undisturbed habitats, deciduous forest and semideciduous forest, and two disturbed habitats, secondary forest and open area habitat, in the Chamela-Cuixmala region of western Mexico. Dung beetle species with high indicator value for each habitat were identified. Beetle abundance, observed species richness and estimated species richness were similar in the three forest habitats, but significantly lower in the open area habitat. A more detailed analysis of species-specific abundances in the three forest habitats revealed some differences. Transects of one of the undisturbed habitats, the deciduous forest, were more similar to the non-adjacent transects of disturbed secondary forest, than to the adjacent undisturbed semideciduous forest transects. Unlike studies in other tropical sites that have found a decrease in equitability in Scarabaeinae assemblages between undisturbed forest and disturbed habitat (particularly open habitats), in the Chamela-Cuixmala region all four habitats showed similar low equitability in community structure, with two or three very dominant species.     

Forest edges have high conservation value for bird communities in mosaic landscapes

A major conservation challenge in mosaic landscapes is to understand how trait‐specific responses to habitat edges affect bird communities, including potential cascading effects on bird functions providing ecosystem services to forests, such as pest control. Here, we examined how bird species richness, abundance and community composition varied from interior forest habitats and their edges into adjacent open habitats, within a multi‐regional sampling scheme. We further analyzed variations in Conservation Value Index (CVI), Community Specialization Index (CSI) and functional traits across the forest‐edge‐open habitat gradient. Bird species richness, total abundance and CVI were significantly higher at forest edges while CSI peaked at interior open habitats, i.e., furthest from forest edge. In addition, there were important variations in trait‐ and species‐specific responses to forest edges among bird communities. Positive responses to forest edges were found for several forest bird species with unfavorable conservation status. These species were in general insectivores, understorey gleaners, cavity nesters and long‐distance migrants, all traits that displayed higher abundance at forest edges than in forest interiors or adjacent open habitats. Furthermore, consistently with predictions, negative edge effects were recorded in some forest specialist birds and in most open‐habitat birds, showing increasing densities from edges to interior habitats. We thus suggest that increasing landscape‐scale habitat complexity would be beneficial to declining species living in mosaic landscapes combining small woodlands and open habitats. Edge effects between forests and adjacent open habitats may also favor bird functional guilds providing valuable ecosystem services to forests in longstanding fragmented landscapes.     

Acridids as indicators of disturbance in dry deciduous forest of West Bengal in India

Acridid communities are sensitive to anthropogenic disturbance and the community structure of acridids plays vital role in functioning the forest ecosystem. They are potentially useful bioindicators for conservation planning and habitat disturbances. Acridid assemblages of three different habitat types based on degree of disturbance as follows five natural sites, five moderately disturbed sites and five highly disturbed sites in Chaupahari forest, West Bengal, India were studied. Diversity, abundance, equitability and species richness of acridid were observed in respect to undisturbed and disturbed habitats. The species richness and diversity of the sites tracked the intensity of disturbance, the greatest value being associated with the natural site followed by the moderately disturbed site and highly disturbed site. The highest species richness and diversity index indicate the suitable habitat for acridid population. Statistical analysis infers that different species show different behavior and the sites are also different in relation to different habitat types.     

Effects of anthropogenic habitat disturbance on local pollinator diversity and species turnover across a precipitation gradient

Anthropogenic habitat disturbance can have profound effects on multiple components of forest biotas including pollinator assemblages. We assessed the effect of small-scale disturbance on local richness, abundance, diversity and evenness of insect pollinator fauna; and how habitat disturbance affected species turnover across the landscape and overall diversity along a precipitation gradient in NW Patagonia (Argentina). We evaluated the effect of disturbance on overall pollinator fauna and then separately for bees (i.e. Apoidea) and non-bee pollinators. Locally, disturbed habitats had significantly higher pollinator species richness and abundances than undisturbed habitats for the whole pollinator assemblage, but not for bees or non-bees separately. However, significant differences in species richness between habitats vanished after accounting for differences in abundance between habitat types. At a local scale Shannon–Weaver diversity and evenness did not vary with disturbance. A β diversity index indicated that, across forest types, species turnover was lower between disturbed habitats than between undisturbed habitats. In addition, rarefaction curves showed that disturbed habitats as a whole accumulated fewer species than undisturbed habitats at equivalent sample sizes. We concluded that small patches of disturbed habitat have a negligible effect on local pollinator diversity; however, habitat disturbance reduced β diversity through a homogenization of the pollinator fauna (in particular of bees) across the landscape.     

Local‐ and landscape‐level effects of land use change on bird diversity in Abiata‐Shalla Lakes National Park,Ethiopia

Understanding the effects of anthropogenic disturbances on biodiversity is important for conservation prioritization. This study examined the effects of vegetation degradation on bird diversity in Abiata‐Shalla Lakes National Park, Ethiopia. We surveyed birds and vegetation structure between January and March 2015 in disturbed (impacted by settlement and agriculture) and undisturbed (not impacted) transects of two vegetation types (savannah woodland and gallery forest). We compared between disturbed and undisturbed transects at local (within vegetation types) and landscape (across vegetation types) levels: (a) avian species richness of the entire assemblage and feeding guilds and (b) species assemblage composition. We found significantly greater mean and total bird species richness of the entire assemblage and insectivore and granivore feeding guilds in the undisturbed transects, while the nectarivore guild was totally absent in the disturbed transects. We also found significant differences in bird species assemblage composition between the disturbed and undisturbed transects both within and across the vegetation types, and bird species assemblage composition at the landscape level was positively correlated with tree abundance and understorey vegetation height. In conclusion, our results demonstrate and add to the increasing body of evidence concerning the adverse effects of human‐induced vegetation change on bird diversity.     

Bird community responses to disturbance in a forestry concession in lowland Bolivia

Bird community characteristics of three sites with different levels of disturbance were studied using transect surveys during the dry season in a subtropical humid forest in Bolivia. One area had been unintentionally burned 4 years prior and selectively harvested (DIS) 1 year prior to sampling. A second area had been selectively harvested 1 year prior to sampling and had no recent history of fire (HAR). Species richness, as assessed by species–time curves and rarefaction, was higher in both altered areas than in undisturbed forest (INT). In general, frugivores and omnivores were more abundant in both altered areas compared to intact forest. Canopy frugivores, understory omnivores and multiple-strata omnivores were most abundant in HAR. Canopy frugivores, near-ground insectivores, understory and multiple-strata omnivores were least abundant in INT, although INT had the highest abundances of canopy insectivores and near-ground omnivores. Richness and abundance of widespread species with low habitat specificity was higher in both areas that experienced disturbance compared to intact forest. Differences in bird community structure between disturbed and intact forest at this site are attributed primarily to the addition of widespread species with less narrow habitat requirements, and possibly to changes in the distribution of different food types.     

Birds in Anthropogenic Landscapes: The Responses of Ecological Groups to Forest Loss in the Brazilian Atlantic Forest

Habitat loss is the dominant threat to biodiversity and ecosystem functioning in terrestrial environments. In this study, we used an a priori classification of bird species based on their dependence on native forest habitats (forest-specialist and habitat generalists) and specific food resources (frugivores and insectivores) to evaluate their responses to forest cover reduction in landscapes in the Brazilian Atlantic Forest. From the patch-landscapes approach, we delimited 40 forest sites, and quantified the percentage of native forest within a 2 km radius around the center of each site (from 6 - 85%). At each site, we sampled birds using the point-count method. We used a null model, a generalized linear model and a four-parameter logistic model to evaluate the relationship between richness and abundance of the bird groups and the native forest amount. A piecewise model was then used to determine the threshold value for bird groups that showed nonlinear responses. The richness and abundance of the bird community as a whole were not affected by changes in forest cover in this region. However, a decrease in forest cover had a negative effect on diversity of forest-specialist, frugivorous and insectivorous birds, and a positive effect on generalist birds. The species richness and abundance of all ecological groups were nonlinearly related to forest reduction and showed similar threshold values, i.e., there were abrupt changes in individuals and species numbers when forest amount was less than approximately 50%. Forest sites within landscapes with forest cover that was less than 50% contained a different bird species composition than more extensively forested sites and had fewer forest-specialist species and higher beta-diversity. Our study demonstrated the pervasive effect of forest reduction on bird communities in one of the most important hotspots for bird conservation and shows that many vulnerable species require extensive forest cover to persist.     

Bird communities in rainforest fragments: guild responses to habitat variables in Tabasco,Mexico

The effects of habitat loss and fragmentation in tropical forests are difficult to separate, as they usually occur concurrently. In the state park La Sierra, in Tabasco, Mexico, the rainforest is being cleared for pasture, and fragments are being used by local inhabitants. This study examined the response of bird feeding guilds to habitat characteristics, including human disturbance, in five fragments of different sizes (1 ∼ 4,500 ha, 2 ∼ 150 ha, and 2 ∼ 80 ha). Using point count observations, 125 species were recorded and were grouped into 11 feeding guilds. As expected, the largest fragment had higher species richness and abundances than the smaller fragments. However, five habitat features differed significantly among fragment sizes, including tree density, the number of tree stumps and the number of trails. Thus the larger fragment was also less disturbed. Fragment size alone was significant only for scavenger species richness, and for the abundance of bark gleaning insectivores and insectivore/nectarivores. Raptors were more diverse and abundant in the large fragment and less disturbed sites. Arboreal frugivores and bark or foliage gleaning insectivores, depended on higher trees and less disturbed sites. A better understanding of the mechanisms that affect persistence is essential for the planning of conservation actions.     

Terrestrial wildlife responses to logging and fire in a Bolivian tropical humid forest

Logging and wildfire are significant anthropogenic disturbance agents in tropical forests. We compared the abundance and species richness of selected terrestrial wildlife taxa including small mammals, amphibians, reptiles, and terrestrial invertebrates in areas burned by wildfire and then logged and in adjacent undisturbed areas of a tropical humid forest in Bolivia. Disturbed areas had 24% less canopy cover than undisturbed areas but had 2.6 times the cover of large woody debris. Understory cover did not differ between disturbed and undisturbed areas. Small mammal abundance and species richness in disturbed areas were 43 and 70% higher, respectively, than in adjacent undisturbed areas. Herpetofaunal abundance did not differ significantly among disturbed and undisturbed areas, but trends for higher abundance were observed for both reptiles and amphibians in disturbed areas. Herpetofaunal species richness was significantly higher in disturbed compared to undisturbed areas. Total terrestrial invertebrate abundance, as estimated by pitfall traps, was significantly higher in undisturbed compared to disturbed areas mostly due to higher abundances of Formicidae and Blattidae. However, two invertebrate groups, Orthoptera and Lepidoptera (larvae) were more abundant in disturbed areas. Wildlife conservation strategies for areas where logging or wildfire occur should take into account species- or guild-specific responses to these disturbance agents.     

Bird richness and composition along an agricultural gradient in New Guinea: The influence of land use,habitat heterogeneity and proximity to intact forest

Abstract We examined variation in bird species richness, abundance and guild composition along an agricultural gradient in New Guinea, and looked for any additive influence of habitat heterogeneity on these variables. The study was based on a grid of survey plots, six plots wide and 24 plots long with the long axis running from a settlement 2.4 km through active and abandoned agricultural plots towards a large area of forest. Each circular survey plot (25 m radius) was assigned to a broad habitat type, ten habitat measures taken, and birds counted for 1 h in each plot. Principal component analysis (PCA) habitat axis 1 described an axis of decreasing forest alteration (larger trees, greater tree densities, fuller canopy) that was positively correlated with distance from the settlement. Bird richness and abundance were highest at intermediate disturbance levels (plots with mid‐range axis 1 scores). Proportions of insectivores and frugivores increased with decreasing forest alteration, while proportions of nectarivores decreased. We calculated three measures of habitat heterogeneity by comparing each plot's PCA score to those of eight neighbouring plots (50–110 m away). These measures reflected how different the plot was to its neighbours, how variable the habitat was around the plot, and the degree to which the plot bordered less disturbed forest. We related these measures to plot bird variable scores independently, and to residuals following regressions of bird scores against PCA scores. Heterogeneity measures had no significant influence on abundance or richness measures, but there were greater proportions of frugivores in plots showing a given degree of habitat alteration if they bordered more pristine habitat. While we readily identified differences in bird communities along the agricultural gradient, the influences of habitat heterogeneity were not striking for birds at this fine scale.