URBAN NOISE PREDICTS SONG FREQUENCY IN NORTHERN CARDINALS AND AMERICAN ROBINS

ABSTRACT

We examined the extent to which acoustic noise in urban environments influences song characteristics and singing behaviour of Northern Cardinals Cardinalis cardinalis and American Robins Turdus migratorius. We predicted that, in response to loud noise, birds would improve signal transmission by (1) increasing singing rate and (2) adjusting song characteristics such as pitch and length. From May—July 2006, 42 cardinals and 53 robins were recorded in forests located within four acoustic environments in central Ohio: rural, residential, commercial, and highway. Following each recording, we measured ambient noise level and recorded information describing location, weather, habitat, and conspecific presence within 75 m. As predicted, frequency range was positively correlated with noise level for both species, but neither song length nor rate was related to noise level for either species. These data support the idea that anthropogenic noise influences avian singing behaviour and acts as a selective force in urban areas.     

The learning advantage: bird species that learn their song show a tighter adjustment of song to noisy environments than those that do not learn

Song learning has evolved within several avian groups. Although its evolutionary advantage is not clear, it has been proposed that song learning may be advantageous in allowing birds to adapt their songs to the local acoustic environment. To test this hypothesis, we analysed patterns of song adjustment to noisy environments and explored their possible link to song learning. Bird vocalizations can be masked by low‐frequency noise, and birds respond to this by singing higher‐pitched songs. Most reports of this strategy involve oscines, a group of birds with learning‐based song variability, and it is doubtful whether species that lack song learning (e.g. suboscines) can adjust their songs to noisy environments. We address this question by comparing the degree of song adjustment to noise in a large sample of oscines (17 populations, 14 species) and suboscines (11 populations, 7 species), recorded in Brazil (Manaus, Brasilia and Curitiba) and Mexico City. We found a significantly stronger association between minimum song frequency and noise levels (effect size) in oscines than in suboscines, suggesting a tighter match in oscines between song transmission capacity and ambient acoustics. Suboscines may be more vulnerable to acoustic pollution than oscines and thus less capable of colonizing cities or acoustically novel habitats. Additionally, we found that species whose song frequency was more divergent between populations showed tighter noise–song frequency associations. Our results suggest that song learning and/or song plasticity allows adaptation to new habitats and that this selective advantage may be linked to the evolution of song learning and plasticity.     

Urban noise and the cultural evolution of bird songs

In urban environments, anthropogenic noise can interfere with animal communication. Here we study the influence of urban noise on the cultural evolution of bird songs. We studied three adjacent dialects of white-crowned sparrow songs over a 30-year time span. Urban noise, which is louder at low frequencies, increased during our study period and therefore should have created a selection pressure for songs with higher frequencies. We found that the minimum frequency of songs increased both within and between dialects during the 30-year time span. For example, the dialect with the highest minimum frequency is in the process of replacing another dialect that has lower frequency songs. Songs with the highest minimum frequency were favoured in this environment and should have the most effective transmission properties. We suggest that one mechanism that influences how dialects, and cultural traits in general, are selected and transmitted from one generation to the next is the dialect''s ability to be effectively communicated in the local environment.     

Bird song and anthropogenic noise: vocal constraints may explain why birds sing higher-frequency songs in cities

When animals live in cities, they have to adjust their behaviour and life histories to novel environments. Noise pollution puts a severe constraint on vocal communication by interfering with the detection of acoustic signals. Recent studies show that city birds sing higher-frequency songs than their conspecifics in non-urban habitats. This has been interpreted as an adaptation to counteract masking by traffic noise. However, this notion is debated, for the observed frequency shifts seem to be less efficient at mitigating noise than singing louder, and it has been suggested that city birds might use particularly high-frequency song elements because they can be produced at higher amplitudes. Here, we present the first phonetogram for a songbird, which shows that frequency and amplitude are strongly positively correlated in the common blackbird (Turdus merula), a successful urban colonizer. Moreover, city blackbirds preferentially sang higher-frequency elements that can be produced at higher intensities and, at the same time, happen to be less masked in low-frequency traffic noise.     

鸟类鸣声地理变异的形成机制

鸣声在鸟类的通讯和性选择中具有重要的意义.鸣声地理变异广泛存在于鸟类中,对其研究有助于了解近缘种的分类和演化历史.鸣声地理变异格局的形成是一个复杂的过程,可能是某一因素起主导、多因素协同作用的结果.主要影响因素有奠基者效应、鸣声漂变、遗传差异、性选择、生境等.年际间鸣声的稳定性和种群内鸣声的变异性,是鸣声地理变异研究中应该重视的问题,通过鸣声学习和扩散机制来研究鸣声地理变异,可能是将来本领域的研究热点.     

Saisonaler Verlauf der Gesangsaktivit?t der Singdrossel(Turdus philomelos), mit Anmerkungen zum nachbrutzeitlichen Gesangsschub

Zusammenfassung Der Zürichbergwald ist eine 350 ha große, bewaldete Kuppe auf 480–680 m ü.M. am Rande der Stadt Zürich. Hier untersuchten wir von 1989 bis 1995 die jahreszeitliche Gesangsaktivität der Singdrossel mit zwei verschiedenen Ansätzen. 1989 und 1991–1995 zählte JH an 123 Tagen auf zwei festgelegten Strecken von 6,1 und 7,1 km die Sänger jeweils in der Stunde der abendlichen Dämmerung. Im gleichen Gebiet zählte RS 1990 an 46 Tagen auf einer 6,7 km langen Strecke am Morgen in der Stunde nach Sonnenaufgang. Ebenfalls 1990 sammelte RS Daten zur Brutbiologie.Die Gesangsaktivität definierten wir mit der Anzahl singender Männchen pro km. Im Jahresverlauf zeigen die Kurven der Morgen- und der Abendaktivität keinen Unterschied. Die Kurve ist deutlich dreiphasig: Ein erster Gesangsschub vom Eintreffen der Vögel bis zum 5. April, danach eine gesangsarme Zwischenzeit bis zum 15. Mai, gefolgt von einem zweiten Gesangsschub, welcher bis zum 5. Juli dauern kann. Allenfalls ist der erste Gesangsschub (stark zeitverschoben) mit dem Beginn der Erstbruten korreliert; die von vielen Singvögel bekannte, markante Gesangsaktivität unmittelbar vor der Eiablage gibt es nicht. Der zweite Gesangsschub ist in der Stärke mit dem ersten vergleichbar. Allerdings liegt er eindeutig am Ende der Brutzeit und kann nicht mit einem Brutparameter (Partnerfindung, Paarbindung, Balz, Brut-Stimulation) in Zusammenhang stehen. Die Funktion dieser nachbrutzeitlichen Gesangsaktivität scheint zukunftsbezogen zu sein. In Frage kommt gehäuftes Singen der Väter vor den Jungen zum Erlernen des Gesangs und des Dialekts, oder/und eine Revier-Voranzeige für die nänchste Brutsaison durch die als philopatrisch bekannten Männchen.

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Annual variation in singing activity of the Song Thrush(Turdus philomelos), with comments on high postbreeding song output

Summary This study was carried out at the Zürichbergwald, a forest east of Zurich (47°20N/08°30E). The study site is a wooded hill of 350 ha between 480 to 680 m asl, characterised by a BeechFagus silvatica forest with patches of SprucePicea abies on 25 % of its surface. The Zürichbergwald is a popular recreational area with moderate forestry exploitation. We did not differentiate acoustic registration from singing activity, and we considered the number of singing males per km to be a measure for singing activity. Two different approaches were applied: in 6 breeding seasons (1989 and 1991 to 1995) JH counted birds at sunset on a 6.1 or 7.1 km circuit (n=123). In 1990, the same was done by RS at dawn each morning on a zigzag track of 6.7 km (n=46). Also in 1990, RS sampled data on the breeding biology of the species.The annual cycle of morning and evening song activity was significantly correlated (Spearman's rank-test; p<0.001 comparing pentads, p=0.025 comparing half of months). Morning and evening revealed the same pattern: there was a first large peak of singing activity early in the year (earliest onset of singing 19 February 1989; latest 8 March 1993) until 5 April (phase I). A period of low song activity followed from 6 April to 15 May (phase II). The period from 16 May to (circa) 5 July was characterized by a second large peak (phase III). Each of the corresponding phases was comparable between morning and evening (Wilcoxon matching pairs; p>0.05). The analysis of evening data reveals that phase II differed from I and from III (p=0.05), but the last two did not differ significantly (Wilcoxon matching pairs; p>0.05).The day with the highest song activity fell in phase I twice (maximum 6.1 singing males/km, 2 April 1995) and 5 times in phase III (maximum 6.9 singing males/km, 23 May 1994).The date females first laid was determined for 53 out of 68 nests. The first brood started 25 March, the last 25 June 1990. Only 3 broods were initiated later than 5 June.The first peak of singing activity could be correlated with the (delayed) onset of breeding, but the second started at the end of the breeding season and persisted too long to be correlated with any breeding activity such as female attraction or stimulation, mate-guarding, etc. We postulate the high post-breeding song output to have several possible functions: Song instruction by father to offspring, or territory announcement for the next season.

     

Lateralization and motor stereotype of song production in the brown-headed cowbird

Song production in adult brown-headed cowbirds(Molothrus ater ater) is lateralized, with a slight right syringeal dominance. The left size of the syrinx produces low-frequency (200–2000 Hz) notes within the introductory note clusters, while the right side produces the higher-frequency (1500–6000 Hz) introductory notes, the interphrase unit (10–12 kHz), and the final high-frequency whistle (5–13 kHz). Cross-correlation analyses reveal that individual cowbirds produce each of their four to seven song types with a distinct stereotyped motor pattern–as judged by the patterns of syringeal airflow and subsyringeal pressure. The acoustic differences across song types are reflected in the differences in the bronchial airflow and air sac pressure patterns associated with song production. These motor differences are particularly striking within the second and third introductory note clusters where there is a rapid switching back and forth between the two sides of the syrinx in the production of notes. These motor skills may be especially important in producing behaviorally effective song. 1994 John Wiley & Sons, Inc.     

基于物种落差分析的公园鸟类多样性提升设计——以湖南常德螺湾湿地公园为例

随着城市化发展,许多公园鸟类栖息环境遭受破坏,导致当前的鸟类多样性与历史上的和周边的都存在较大差异,为此,我们从项目区域的当前-周边-历史三者间在鸟类物种及其栖息地上的落差分析入手,以此确定目标物种及其栖息地,并加以归类,从而有针对性地进行相关设计。2016年5月至2017年3月在湖南常德柳叶湖螺湾湿地公园开展的鸟类多样性提升设计中,通过实地调查并结合文献查阅,记录到项目区域16种,周边79种,历史上146种鸟类,运用三者间的物种落差分析法确定主要的21种可恢复目标物种和4种栖息地类型,结合项目区域及周边空间特点,将项目区域划分为4个区域,在各区域内设计并营建相应的栖息地,再配套采用多种鸟类招引措施。至2017年3月,项目区鸟类已可实地观察到39种,并于2017年12月吸引到超过2000只的野鸭群来此越冬。以上实际效果表明,设计有效地提升了湿地公园鸟类多样性且增加了景观要素,可充分发挥生物保护功能。     

城市公园特征对广西柳州繁殖鸟类多样性的影响

城市化是导致生物多样性波动的主要因素之一。为了探讨城市公园特征参数（如公园面积、林地面积和距市中心距离等）对城市鸟类物种多样性和功能多样性的影响,于2021-04—2021-08,采用样线法对广西柳州12个城市公园进行鸟类监测。利用多元回归和广义线性模型分析公园特征参数对鸟类物种多样性和功能多样性的影响。结果显示：城市公园面积与鸟类物种丰富度呈正相关,鸟类功能多样性RaoQ指数与距离市中心距离呈正相关,鸟类功能均匀度指数与林地面积和距离市中心距离呈负相关,这表明城市化程度对鸟类功能多样性有显著影响。柳州市繁殖鸟类功能性状呈聚集趋势,随机过程可能是群落组配的主要驱动力,标准化效应值（SES.MNTD.FD）与林地面积呈正相关性。强调了城市公园特征参数对鸟类多样性影响的多维性,研究结果为柳州市及其他类似中小型城市提供了鸟类多样性保护和城市公园规划的重要数据支持和实践指导。建议通过增加城市公园和林地面积,以及减缓城市化进程,有效保护和提升城市鸟类的物种多样性和功能多样性。     

Changes in Nothofagus pumilio forest biodiversity during the forest management cycle. 2. Birds

Human activities, such as logging, modify the forest structure and the microenvironments of the original Nothofagus forests. The aims of this work were to evaluate changes in the diversity and relative abundance of birds and to analyze their trophic relationships with insect and plant communities along the Nothofagus pumilio forest management cycle. Data was collected using a point sampling method along transects located in different forest structures during the summer season, by direct (sight) and indirect (hearing) recognition following sunrise. Bird diversity and abundance significantly varied along the forest management cycle. Seven new species appeared after harvest, but the total number did not vary by the end of the forest management cycle, and there was no significant loss of species. Bird abundance was directly related to the insect abundance and plant biomass. Relationship between groups (lower plants, monocotyledons and dicotyledonous) is also discussed. Major studies in bird ecology are necessary to develop new silvicultural alternatives based on the more sensitive species to harvest. Forest management strategies and mitigation alternatives must be incorporated into forest planning in order to maintain the original structure of bird communities and the equilibrium with other forest species.     

Summer bird population in the central part of the Prilenskoe plateau

Bird censuses were taken by routing in the central part of the Prilenskoe plateau, a region poorly explored by ornithologists. The summer population of birds in different habitats at watersheds, in valleys and along riverbanks has been characterized on the basis of the original data obtained.