Variation in song characteristics and responses to anthropogenic noise of Lincoln’s Sparrow (Melospiza lincolnii) in the boreal forest
Creators: Sanchez Ulate, Natalie Viviana
Publisher: name: University of Alberta Library
Year: 2022

<p>The study of avian vocalizations intrigues humans in many ways, in part because song production has many similarities with human speech. Since the development of technologies to record and analyze songs, the study of avian vocalizations has provided insights into song learning and its function in animal communication. One of the initial observations was the geographic variation of songs within the same species, which led to the finding of song learning being mediated by social interactions. Past studies showed that songbirds are capable of adapting their songs both in evolutionary time and within their lifetimes. Natural conditions can also influence song features; for example, vegetation acts as a selective force shaping the acoustic features of songs. In recent years, there has been increasing awareness about the effect of anthropogenic noise on animals that rely on acoustic signals for communication. The general responses to noise described for birds in the field are a decrease of species richness close to the noise source, changes in avian assemblages, and behavioural changes in even tolerant species. The main objective of this thesis was to investigate what factors influence the persistence of a common sparrow species, the Lincoln’s Sparrow (Melospiza lincolnii), in environments modified by industrial activities, particularly with noise. The objectives of my thesis were to: 1) quantify the geographic variation of Lincoln’s Sparrow songs and the variation associated with vegetation structure; 2) determine if the occupancy of Lincoln’s Sparrow differs in areas with industrial noise compared to less disturbed, quiet areas; and 3) identify which vocal traits are associated with persistence of Lincoln’s Sparrow in noisy environments.<br>
To address the first objective, I studied the geographic variation of Lincoln’s Sparrow songs in natural conditions using recordings obtained with autonomous recorders units (ARUs) in Alberta, Canada. I created a song catalogue of 74 individuals, compared syllable sharing between individuals from different locations across Alberta using spectrograms, measured acoustic features of songs, and classified shared and unshared syllables. I described the relationship between acoustic features of songs and proportion of vegetation along a spatial distance of 795.2 km. I found that Lincoln’s Sparrow had songs with higher frequencies and wider bandwidths in areas with a higher proportion of open areas and deciduous forest. Unshared syllables were lower in frequency in areas with denser vegetation. <br>
To address the second objective, I estimated the occupancy of Lincoln’s Sparrow along a gradient of industrial noise created by the oil gas industry in Northern Alberta, Canada. Using ARUs, I detected the locations where the species was present. I also developed novel methods to obtain relative measurements of noise amplitude from sound files recorded by ARUs. Lincoln’s Sparrow occupancy slightly decreased in the gradient of noise. Individuals seem to tolerate certain levels noise and also are attracted to the open habitats that are associated with infrastructure created by the energy sector, which typically includes combinations of remnant forest and open areas with scattered shrubs. <br>
To address the third objective, I studied vocal responses to chronic industrial noise generated by compressor stations. I recorded 15 Lincoln’s Sparrow males close to compressor stations and 15 males in quiet areas, using two methods: manual recorder and ARUs deployed on their singing perch and on the nearest shrub to the singing perch. I obtained acoustic features of 400 songs (high frequency, low frequency, bandwidth, and peak frequency), song length, singing rate, and song relative amplitude. I found that singing rate and relative amplitude of songs were higher in noisy areas. I performed a song attenuation test of a Lincoln’s Sparrow song at different distances (0 - 50 m) and heights (1.5, 2.5, 3.5 m) in a noisy and a quiet area. I found increased attenuation as distance increased relative to the control, suggesting a new selection pressure for short distance communication in noisy areas. <br>
In conclusion, I showed for the first time high geographic variation in Lincoln’s Sparrow song associated with variation in vegetation structure in natural settings. In the oil sand industries, Lincoln’s Sparrow was detected in open areas that also have industrial noise, showing a tolerance to inhabit areas influenced by anthropogenic noise. This tolerance for anthropogenic noise may be facilitated by increasing the singing rate and the amplitude of their songs.</p>