新疆阜康地区家麻雀的巢址选择

2013年7月和2014年5~7月,在新疆阜康地区对家麻雀(Passer domesticus)的巢址选择进行调查,以分析影响家麻雀巢址选择的生态因子。在研究区内共找到75个家麻雀的自然巢,筑巢生境为农田和防护林带,均在白杨(Populus adenopoda)林和胡杨(P.euphratica)林中的树上筑巢。其中,繁殖成功巢40个,繁殖失败巢20个,15个巢未记录到繁殖结果。在研究区内的居民房屋、墙洞等没有发现家麻雀的巢。采用逻辑斯蒂回归和主成分分析方法对筑巢地海拔(m)、筑巢树种、筑巢树高(m)、巢距路距离(m)、巢距地面高度(m)、巢上方盖度(%)、筑巢树胸径(m)、最近邻巢的距离(m)这些家麻雀的主要巢址参数进行分析,结果表明,影响新疆阜康地区家麻雀巢址利用的主要因素为巢距地面高度(m)、巢上方盖度(%)和巢距路距离(m)。对家麻雀繁殖成功巢(n=40)和繁殖失败巢(n=20)的巢址参数进行比较,两者差异不显著,因而推测,在研究区域的尺度内,家麻雀的巢址选择并不是影响其繁殖成效的主要因素。     

朱砂叶螨对甲氰菊酯、阿维菌素,哒螨灵及其混剂抗性遗传力的分析(英文)

采用域性状分析法 ,估算了朱砂叶螨对 5种杀螨剂 (3种单剂和 2种混剂 )的抗性现实遗传力 ,并对 5种药剂的抗性风险进行了评估。把采自重庆北碚田间的朱砂叶螨种群 ,在室内不施药情况下饲养 6 0余代 ,以此作为抗性筛选的敏感品系。分别单一连续汰选近 30代 ,朱砂叶螨对甲氰菊酯、阿维菌素、哒螨灵、哒螨 -阿维 (哒螨灵 :阿维菌素 =7 4 :0 1,m m)和甲氰 -阿维 (甲氰菊酯 :阿维菌素 =8 9:0 1,m m)的抗性分别达 6 5 5 5、5 82、1 2 3、5 2 0和 1 4 2 倍 ;抗性现实遗传力分别为 0 2 16 7、0 0 96 7、0 0 130、0 0 80 0和 0 0 172。在实验室选择条件下 ,预计抗性增长 10倍时 ,甲氰菊酯、阿维菌素、哒螨灵、哒螨 -阿维 (哒螨灵 :阿维菌素 =7 4 :0 1,m m)和甲氰 -阿维 (甲氰菊酯 :阿维菌素 =8 9:0 1,m m)分别需要 15、34、333、4 2和 2 0 0代。甲氰菊酯抗性风险较高 ,其次是阿维菌素、哒螨 -阿维 (哒螨灵 :阿维菌素 =7 4 :0 1,m m)、甲氰 阿维 (甲氰菊酯 :阿维菌素 =8 9:0 1,m m) ,哒螨灵抗性风险较低。混剂哒螨 阿维 (哒螨灵 :阿维菌素 =7 4 :0 1,m m)不能延缓朱砂叶螨对两单剂哒螨灵和阿维菌素的抗性发展 ,而混剂甲氰 阿维 (甲氰菊酯 :阿维菌素 =8 9:0 1,m m)却能有效延缓朱砂叶螨对两单剂     

荒漠伯劳巢址选择和繁殖成功

2011年5～7月对甘肃安西极旱荒漠国家级自然保护区(N40°21'～40°22',E96°13'～96°14',海拔1 306 m)荒漠伯劳(Lanius isabellinus)巢址选择和繁殖成功进行研究。调查了58巢的巢址因子,巢主要位于营巢树主枝上,巢距地面高度多为2.0～2.5 m。主成分分析结果表明,巢距地面高度、营巢树高度、营巢树胸径和营巢处树干直径是影响荒漠伯劳巢址选择的主要因素,这也是荒漠伯劳适应繁殖地大风天气的结果。既调查巢址数据又明确繁殖情况的49个巢中,红柳(Tamarix ramosissima)(5棵)上巢的繁殖成功率明显高于沙枣(Elaeagnus angusifolia)(43棵)和胡杨(Populus euphratica)(1棵)上的巢,原因可能是红柳郁闭度大。已知窝卵数和繁殖情况的30个巢中,窝卵数分别为2(1巢)、4(7巢)、5(18巢)、6(4巢)。卡方检验结果表明,窝卵数和繁殖成功率之间差异不显著(χ2=3.921,df=3,P0.05)。发现的63个巢中跟踪监测了54个巢(包括调查巢址数据的和未调查巢址数据的)的繁殖情况,54巢中37巢繁殖成功,成功率为68.52%。所有繁殖失败的巢均为产卵阶段或育雏早期阶段由于同类的破坏而导致繁殖失败,繁殖失败巢的数量随着相邻最近巢的距离的增加而减少,因而,繁殖失败可能与种群密度以及种内竞争有关。     

黑颈长尾雉的巢址选择

2004年至2005年,在广西百色岑王老山自然保护区对黑颈长尾雉(Syrmaticus humiae)的巢址选择进行了研究。野外工作中共发现5巢,其中3巢在针叶林中,2巢在灌草丛中。结果表明,黑颈长尾雉的巢都是选择在向阳的东南坡且位于坡的下位,靠近林缘、水源和林间小道。对巢址10 m×10 m和1 m×1 m植被样方不同层次盖度作统计发现,黑颈长尾雉巢址选择更多的依赖于灌木层和草本层的盖度。     

扎龙保护区人工林内中华攀雀巢址特征分析

作者2011年9 ～ 10月在黑龙江省扎龙国家级自然保护区对人工林内中华攀雀(Remiz consobrinus)的巢址特征进行了研究.研究期间共发现36巢,选取巢距地面距离、巢距主干距离、巢距挂枝末端距离、巢树胸径等9个巢址因子进行主成分分析.结果表明,巢下生境、巢距地面距离和巢距主干距离以及巢距挂枝末端距离在中华攀雀巢址选择中起主要作用;巢树胸径、巢向和巢挂枝年龄次之.中华攀雀巢距地面(5.59±1.44)m,距主干距离为(1.81±0.50)m,距挂枝末段距离为(0.10±0.04)m,巢树胸径(0.29±0.08)m.巢距地面高度(P =0.002 3)和巢距明水面距离(P =0.003 7)在芦苇沼泽与林地草甸2种生境类型之间差异显著,巢树胸径在林地草甸与房屋农田2种生境类型之间差异显著(P=0.003 4),不同生境类型之间巢距主干距离、巢距挂枝末端距离和巢挂枝年龄无显著差异.     

长尾缝叶莺和栗头缝叶莺的巢址选择比较

2013年3—6月、2014年3—6月,在广西弄岗地区对长尾缝叶莺(Orthotomus sutorius)和栗头缝叶莺(O.cuculatus)的巢址特征进行调查,以比较两者巢址选择的差异。野外共发现64个长尾缝叶莺和47个栗头缝叶莺的巢,其中长尾缝叶莺有60巢(93.7%)位于村庄林下,4巢(6.3%)位于山脚阔叶林;栗头缝叶莺有3巢(6.3%)位于村庄林下,44巢(93.6%)位于山脚阔叶林。主成分分析结果表明:影响长尾缝叶莺巢址选择的主要生态因子为筑巢植物的高度、距林缘距离和海拔;影响栗头缝叶莺巢址选择的主要因素为筑巢植物的高度、巢四周的隐蔽度和距山峰的距离。判别分析结果表明,距山峰的距离是区分2种缝叶莺巢址选择的最重要参数。     

陇东地区金翅雀的巢址选择

为探究金翅雀(Chloris sinica)营巢是否偏好某些树种以及偏好原因,于2017—2019年4—8月,在陇东学院校园内,开展了金翅雀巢址选择调查。180个金翅雀巢址分析显示:金翅雀营巢利用圆柏(Juniperus chinensis)、刺柏(Juniperus formosana)、侧柏(Platycladus orientalis)、日本晚樱(Cerasus serrulata)等17种乔木,其中圆柏(χ2=13.6,df=1,P=0.000)和刺柏(χ2=9.8,df=1,P=0.002)是金翅雀选择的主要树种;与其他巢址比较,圆柏和刺柏巢址的巢树树冠直径(DNTC)、巢-缘距(DEC)和巢树-最近树距离(DT)显著小于其他树种巢址的相应参数,而圆柏和刺柏巢址的巢树树冠高度(HNTC)、巢-冠底距离(DBC)、巢树-草地距离(DM)、可利用林木数量(NT)和隐蔽度(CC)都显著大于其他树种巢址的相应参数(T或Mann-Whiteny U检验,全部P0.05);差异显著的8个巢址参数(DNTC、DEC、DT、HNTC、DBC、DM、NT和CC)的因子分析表明,环境隐蔽性、巢位隐蔽性和巢位不易接近性是导致金翅雀偏好在圆柏和刺柏上营巢的主要因素。本研究结果可为城市环境绿化中如何保护鸟类提供参考。     

甘肃南部蓝马鸡的巢址选择

蓝马鸡(Crossoptilon auritum)是我国特有的雉类,仅分布在青海东部、东北部,甘肃西北部及南部,四川西北部以及宁夏西部。2007和2008年在甘肃南部林区对蓝马鸡巢址进行了研究。在发现的12个蓝马鸡巢中,4巢(33.3%)在乔木下,4巢(33.3%)在岩石上或者岩洞内,2巢(16.7%)在枯枝下,2巢(16.7%)在灌丛下。U检验和T检验表明,坡位、坡度、灌木高度、灌木数量、灌木盖度、0.5m植被盖度、1.0m植被盖度、2.0m植被盖度、干扰度等9个生态因子在巢址(n=12)与对照样方(n=24)中存在显著差异。对13个变量进行逐步判别分析,结果显示,高坡位、高林下植被盖度及低干扰度是蓝马鸡巢址优先选择的生态因子。     

盐城滨海海堤林中黑尾蜡嘴雀和黑卷尾的巢址选择与生态位

繁殖期鸟类的巢址选择受到很多因素的影响。许多雀形目鸟类选择在树上营巢,但开阔的沿海地区通常缺乏成片的自然林地,人工种植的廊道状海堤林则成为多种雀形目鸟类的营巢地。2018年4-8月在江苏省大丰麋鹿国家级自然保护区境内的海堤林中,对繁殖鸟类巢的分布及两种优势繁殖鸟类---黑尾蜡嘴雀(Eophona migratoria)和黑卷尾(Dicrurus macrocercus)的巢址选择进行了研究,分析了两种鸟类的生态位重叠情况。结果表明:海堤林生境中共发现10种繁殖鸟的127个巢,鸟巢多数位于5 m以上的空间;影响黑尾蜡嘴雀巢址选择的主要因素是巢树和灌木等,巢位置、乔木和安全等因素是次要因素(前5主分量累计贡献率为71.9%);影响黑卷尾巢址选择的主要是巢树因素和灌木因素,巢向、乔木因子是次要因素(前5主分量累计贡献率78.0%);在巢址生态位分化上:两种鸟类的巢向(Utest,Z=-3.013,P<0.01)、巢高(Utest,Z=-6.718,P<0.01)、巢位置(Utest,Z=-5.402,P<0.01)、隐蔽性(Utest,Z=-4.081,P<0.01)选择上存在极显著的差异,两者在这些因子存在生态位分化;两种鸟类在12个巢址因子选择上的生态位重叠值都较大(最小值为0.500,最大值为0.998),存在激烈的种间竞争;在滨海地区,海堤林是依赖树木筑巢繁殖鸟类的重要栖息地,需要加强保护与管理。     

角百灵和小云雀的巢址选择与竞争共存

于 2 0 0 0— 2 0 0 2年的鸟类繁殖期在中国科学院海北高寒草甸生态系统定位站 ,测定了 2 7窝角百灵(Eremophilaalpestris)和 4 3窝小云雀 (Alaudagulgula)的巢址特征 ,观察了两者在繁殖期巢数的季节变化 ,并运用稳定性同位素技术测定了育雏食物 ,对两种百灵的巢址特征和食物重叠度进行了比较。结果表明两者的巢址特征存在着显著的不同 :角百灵的巢开放度为 92 16 % ,小云雀的为 34 6 1% ,前者的巢开放度显著大于后者(P <0 0 1) ;角百灵距巢 10 0cm范围内遮蔽物的数量为 0 0 7± 0 2 6 ,小云雀的为 2 5 7± 1 19,前者显著少于后者 (P <0 0 1) ;角百灵巢址植被的高度和盖度也显著小于小云雀的 (P <0 0 1)。角百灵和小云雀均以小型昆虫育雏 ,育雏食物的资源重叠程度很高 ,为 0 895 7;而且两者的繁殖季节和繁殖强度也是相互重叠的。这两种百灵鸟类在巢址的选择上存在着一种代价和利益的权衡关系 ,巢址选择是捕食压和热条件共同作用的结果。二者共存的机制是巢址上的分化     

Nest‐site selection by golden plover: why do shorebirds avoid nesting on slopes?

It is widely known that many upland-breeding shorebirds tend to nest on plateaus but to date no studies have put forward explanations for this phenomenon. We examined the effect of slope and habitat on the distribution of ground-nesting golden plover Pluvialis apricaria at two study sites in County Durham, U.K. Golden plovers showed strong selection for nesting on flat ground. Habitat significantly affected nest-site location on one study site (heather burnt within the past 2 years was favoured and older stands of heather were avoided) but not on the other. Fifty-nine per cent of all nests failed. We attributed 95% of all losses to predation. Seventy-five per cent of nests, in which the predator was identified, were taken by ground predators, mainly stoats Mustela erminea . Nests on flat ground had significantly higher rates of survival than those on slopes. Nest survival did not vary significantly with habitat type nor with vegetation height or density around the nest. Neither habitat type, vegetation height nor vegetation density around nests differed between nests on slopes and on flat ground. In addition, individuals that nested on flat ground tended to have less black on their underparts (a suggested indicator of dominance). We suggest that birds nesting on slopes are less efficient at avoiding nest predation than those nesting on the flat. The nature or degree of a bird's response to a predator may be related to the efficiency of individual anti-predator responses and/or to visibility from the nest. This study cannot differentiate between these two explanations. We encourage further work to investigate differences in behaviour between individuals nesting on slopes and those on flat ground.     

Availability and selection of arboreal termitaria as nest-sites by Orange-fronted Parakeets Aratinga canicularis in conserved and modified landscapes in Mexico

Few studies have investigated the use of termitaria by nesting parrots, or how this may be affected by habitat transformation. We determined selection of termitaria by nesting Orange-fronted Parakeets Aratinga canicularis , and evaluated the effect of habitat transformation on the availability of termitaria nest-sites for Parakeets in the tropical dry forest of Western Mexico. Availability of termitaria was quantified in 24 survey plots in a factorial design of six 1-ha plots in each of conserved and modified, deciduous and semi-deciduous forest. Characteristics of termitaria were determined in survey plots, as well as 21 nest-termitaria used by Parakeets, and their nearest adjacent termitarium. There was an overall density of 1.6 termitaria/ha suitable for nesting by Parakeets, which did not differ between habitats, although only 8% of apparently suitable termitaria were occupied by nesting Parakeets. However, termitaria in conserved semi-deciduous forest were significantly higher above the ground, and termitaria in conserved deciduous forest were significantly smaller in volume. In the modified landscape, termitaria were significantly lower and their volume significantly larger than in conserved landscapes. Termitaria used by nesting parrots were at a significantly greater height above the ground than the nearest adjacent termitaria. Termitarium volume did not reliably predict the likelihood of nest-site selection, although Parakeets only used termitaria between 15 and 150 l. Parakeets nesting in modified habitats used termitaria at a significantly lower height than Parakeets nesting in conserved habitat. It is unclear whether this represents a decline in nest-site quality in modified habitats, which could affect reproductive success of Parakeet populations in fragmented landscapes.     

Plasticity of nest-site selection in the trumpeter finch: A comparison between two different habitats

In habitats with more predators, a species is expected to breed in safer sites and be less successful than in predator-impoverished habitats. We tested this hypothesis by studying nest-habitat selection and nest predation in two populations of Trumpeter finch (Bucanetes githagineus). One breeds in a predator-rich habitat (Tabernas, Iberian Peninsula), and the other is found on an island with fewer predators (La Oliva, Canary Islands). In both localities, we studied the features of nests in two different substrates, on the ground and in cliffs, including visibility and position in the cliff. We measured the habitat characteristics in a series of plots around the ground nests and compared them to random points. We also studied the influence of nest features and habitat selection on predation of both nest types. Trumpeter finches built more nests in cliffs in Tabernas, probably because there are more cliffs available there. In this locality, the patches selected for ground nesting had below-average vegetation cover, lower vegetation height, and were on steeper slopes. In La Oliva, they selected above-average vegetation height and steeper slopes. Cliff nests were less predated than ground nests in La Oliva, but not in Tabernas. The only variable that affected survival rates in Tabernas was the height of vegetation around ground nests, with nests in lower vegetation having higher survival rates. These results suggest that locality-related differences in habitat selection by vegetation height could be related to the different predator assemblages present in any given area, though we cannot rule out confounding influences of other differences between the two sites.     

Nesting Habitat of the Lilac-crowned Parrot in a Modified Landscape in Mexico

Parrot populations are being increasingly pressured to occupy modified or fragmented landscapes, yet little is known of the habitat requirements of most species, particularly with regard to the effects on breeding habitat. We evaluated nesting habitat of the lilac-crowned parrot Amazona finschi in the modified landscape of coastal Michoacan in Mexico. We located 90 parrot nests in 12 tree species in Michoacan, with lilac-crowned parrots presenting a narrow niche-breadth of tree species used for nesting. Considering an additional 82 nest trees recorded for lilac-crowned parrots in Jalisco, we determined a 51 percent similarity in cavity resource use by parrots in the two dry forest regions. Overall, the predominant nest tree species with 76 percent of nests were Astronium graveolens , Piranhea mexicana , Brosimum alicastrum , and Tabebuia spp., all characteristic of semi-deciduous forest. Only 8 percent of nests occurred in trees characteristic of deciduous forest. Parrots utilized large trees with canopy level cavities as nest sites, and preferred conserved semi-deciduous forest for nesting, with fewer nests than expected in deciduous forest and transformed agricultural land. Nest areas in semi-deciduous forest occurred on significantly steeper terrain, as remnant semi-deciduous forest is restricted to steep ridges and canyons. Those parrot nests in modified habitats and forest patches were located near to continuous forest, with nest trees in open agricultural land being significantly closer to continuous forest than nests in disturbed forest patches. These results demonstrate the importance of conserved semi-deciduous forest as breeding habitat for the threatened, endemic lilac-crowned parrot, making wild populations of the species vulnerable to the high rate of transformation and fragmentation of tropical dry forest.     

家燕营巢特征及其对城市环境的适应性

城市面积在全球范围内迅速扩张,一些鸟类种群通过改变营巢特征,在与自然生境截然不同的城市中筑巢繁殖。但目前城市环境对于鸟类营巢影响的研究较缺乏。为了解鸟类营巢对城市环境的适应,于2016、2019年在黑龙江哈尔滨的城市与乡村环境,分别测量家燕（Hirundo rustica）巢（如,大小及形状）及巢址特征等（如,距地面和屋顶距离）参数,以探究：（1）家燕巢特征在乡村及城市生境是否存在差异？（2）家燕巢特征在年际间是否存在变化？并为城市家燕种群的保护提供理论依据及合理建议。研究采用Kruskal-Wallis秩和检验以及Wilcoxon秩和检验比较分析所测量的巢特征参数在城乡之间、年际间的差异,并对组间参数进行线性判别分析（LDA,Linear Discriminant Analysis）。结果发现,城乡间具有显著差异：（1）与乡村相比,城市巢距离屋顶更远,距地相对更近（P<0.05）;（2）城市巢更浅（P<0.05）;（3）从2016到2019年,城市和乡村巢都变得更深,半径更大（P<0.05）。根据这些发现,推测城市楼房建筑的楼道为家燕繁殖提供了相对更为封闭、安全的环境,旧巢及较为丰富的支撑物为家燕提供了适宜的巢址,有可能节省亲鸟在营巢上的繁殖投入;但同时应当警惕门窗关闭、资源受限、人为干扰等不利因素可能造成的生态陷阱。     

Compounding effects of habitat fragmentation and predation on bird nests

Habitat fragmentation and invasive species are two of the greatest threats to species diversity worldwide. This is particularly relevant for oceanic islands with vulnerable endemics. Here, we examine how habitat fragmentation influences nest predation by Rattus spp. on cup‐nesting birds in Samoan forests. We determined models for predicting predation rates by Rattus on artificial nests at two scales: (i) the position of the bird's nest within the landscape (e.g. proximity to mixed crop plantations, distance to forest edge); and (ii) the microhabitat in the immediate vicinity of the nest (e.g. nest height, ground cover, slope). Nest cameras showed only one mammal predator, the black rat (Rattus rattus), predating artificial nests. The optimal model predicting nest predation rates by black rats included a landscape variable, proximity to plantations and a local nest site variable, the percentage of low (<15 cm) ground cover surrounding the nest tree. Predation rates were 22 ± 13% higher for nests in forest edges near mixed crop plantations than in edges without plantations. In contrast, predation rates did not vary significantly between edge habitat where the matrix did not contain plantations, and interior forest sites (>1 km from the edge). As ground cover reduced, nest predation rates increased. Waxtags containing either coconut or peanut butter were used as a second method for assessing nest predation. The rates at which these were chewed followed patterns similar to the predation of the artificial nests. Rural development in Samoa will increase the proportion of forest edge near plantations. Our results suggest that this will increase the proportion of forest birds that experience nest predation from black rats. Further research is required to determine if rat control is needed to maintain even interior forest sites populations of predator‐sensitive bird species on South Pacific islands.     

Nesting habitat characteristics of Marbled Murrelets occurring in near‐shore waters of the Olympic Peninsula,Washington

Marbled Murrelets (Brachyramphus marmoratus) are listed as threatened in the portion of their range extending from British Columbia to California due to loss of nesting habitat. Recovery of Marbled Murrelet populations requires a better understanding of the characteristics of their nesting habitat in this part of their range. Our objective, therefore, was to describe their nesting habitat in Washington State and Vancouver Island, British Columbia. We captured Marbled Murrelets from 2004 to 2008, fitted them with radio transmitters, and followed them to nests (N = 20). We used Cohen's unbiased d effect size to assess differences between forest plots surrounding nest sites and nearby control sites (N = 18). Nest sites had less canopy cover of the dominant conifers and fewer, but larger, trees than control sites. Nest sites also had greater percentages of trees with platforms >10 cm diameter and >15 cm diameter, and more platforms of these sizes than control sites. The mean diameter at breast height of nest trees was 136.5 cm (range = 84–248 cm) and all but one nest was in dominant or co‐dominant tree species. At the landscape scale, we used vegetation maps derived from remotely sensed data and found greater canopy cover, higher density of mature trees, more platforms >10 cm/ha, and more old‐growth habitat at nest sites than at random sites. Our findings suggest that, at the site scale, nesting Marbled Murrelets selected the most suitable features of forest structure across expansive potentially suitable habitat. Our landscape‐scale analysis showed that habitat features in nesting stands differed from those features in available stands in the murrelet's range in Washington. We also found that stands with nests were less fragmented than available forest across murrelet range. All nest sites of radio‐tagged birds in Washington were in protected areas in mostly undisturbed forest habitat. Conservation of these areas of inland nesting habitat will be critical to the recovery of Marbled Murrelet populations.     

Nesting failure in Finnish Northern Goshawks Accipiter gentilis: incidence and cause

Habitat composition is an important factor influencing nesting failure probability in birds. However, although various habitat effects such as fragmentation and edge density are known to have clear negative effects on the breeding success of passerines, the role that habitat composition plays in shaping nesting failure patterns among other avian groups is less well known. We studied nesting failure in a large forest raptor, the Northern Goshawk Accipiter gentilis , during the period 1999–2003 in Finland. Illegal human persecution was found to constitute a major cause of failure among nests where cause could be determined accurately (comprising c . 60% of all failed nesting attempts). Egg predation by corvids and nestling predation by Eagle Owls Bubo bubo were also common. However, the exact cause of nesting failure could not be inferred in every case. Overall, the degree of initial parental investment (clutch size and egg volume) was significantly smaller in nests that failed than in nesting attempts that were successful. This did not apply to nests that were destroyed by humans, in which investment was at a level equal to nests that were successful. Although the probability that a nesting attempt would fail was also related to small-scale nest concealment, nesting failure probability was not associated with main prey density or several measures describing territorial habitat composition at larger scales. Small initial parental investment, not habitat composition, is thus the major correlate of nesting failure in Goshawks.     

Nest-Building by Chimpanzees (Pan troglodytes verus) at Seringbara, Nimba Mountains: Antipredation, Thermoregulation, and Antivector Hypotheses

The construction of nests (or beds) for sleeping is a chimpanzee universal, yet little is known about the adaptive function of nest-building. We present an in-depth study of nest-building by unhabituated chimpanzees at the Seringbara study site in the Nimba Mountains, Guinea, West Africa. We recorded 1520 chimpanzee nests over 28 mo during three study periods between 2003 and 2008. We investigated where chimpanzees built their nests, both across the home range and in nest trees, and assessed how altitude and habitat type affected nest site selectivity. We examined whether or not chimpanzees were selective in nest tree choice regarding physical tree characteristics and tree species and assessed plant species preference for both tree- and ground-nesting. We tested three, nonmutually exclusive, hypotheses for the function of arboreal nest-building. We assessed whether selectivity for nest tree characteristics reflected an antipredator strategy, examined whether nesting patterns (both arboreal and terrestrial) and nesting height were influenced by variation in climatic conditions (temperature, humidity, wind), and measured mosquito densities at ground level and in trees at 10 m and related mosquito densities to nesting patterns. Chimpanzees preferred to nest above 1000 m and nested mainly in primary forest. They preferred relatively large trees with a low first branch, dense canopy, and small leaves and showed preference for particular tree species, which was stable across years, whereas plant choice for ground-nesting was largely based on plant availability. We found no support for the antipredation hypothesis, nor did mosquito densities explain arboreal nest-building. The thermoregulation hypothesis was supported, as both nesting patterns and nest-height variation across seasons reflected a humidity-avoidance strategy. Chimpanzees nested higher in trees and at higher altitudes in the wet season. In sum, chimpanzees were selective in their choice of nest sites, locations, and materials, and tree-nesting patterns at Seringbara were best explained by a thermoregulation strategy of humidity avoidance.     

Nest Selection by Cavity-nesting Birds in Subtropical Montane Forests of the Andes: Implications for Sustainable Forest Management

Development of sustainable forestry has been hampered in tropical countries by a scarcity of research on the ecological effects of logging. We focused on cavity-nesting birds, a group known to be sensitive to logging. Cavities used for nesting were not a random subset of all available suitable cavities. Birds selected cavities that were relatively high above the ground, had smaller entrances, and were excavated by woodpeckers. The use of tree species was also not random: Calycophyllum multiflorum , Blepharocalyx gigantea , and Podocarpus parlatorei were disproportionately important. Cavity nests were also more likely to be found in areas with trees with high mean diameter at breast height. This study emphasizes the need to maintain some unlogged forest patches within logging areas and retain certain species of trees. This study has implications for forest management in Argentina, where a new law mandates the sustainable use of forest resources and where many landowners are interested in forest certification.