Anthropogenic noise negatively affects wildlife in a wide range of taxonomic groups. Especially for birds, a substantial number of observational studies have now shown negative associations between... Show moreAnthropogenic noise negatively affects wildlife in a wide range of taxonomic groups. Especially for birds, a substantial number of observational studies have now shown negative associations between noise pollution and abundance and diversity along roadsides. Researchers investigating birds’ behavioural responses to high level noise to date have mostly focused on the immediate adjustment of vocal signalling behaviour. However, there is more than one mechanism by which birds might cope with increasing noise levels. They may show immediate behavioural reactions, such as spatial avoidance and/or vocal adjustment, but also more ontogenetic adjustments with long-term consequences like changes in sensory and personality traits. To test these potential effects of traffic noise on birds, I conducted a series of experiments using zebra finches. I have demonstrated that traffic noise per se can contribute to spatial avoidance in birds and cause variation in parental behaviour, and that there can be changes in noise avoidance behaviour in the course of a lifetime. These results provide new insights into the potential impacts of noise on birds. Show less
The aim of this thesis is to shed light on whether some capacities that are considered linked to, or characteristic for, language are shared between humans and nonhuman animals, which can help to... Show moreThe aim of this thesis is to shed light on whether some capacities that are considered linked to, or characteristic for, language are shared between humans and nonhuman animals, which can help to understand the basic cognitive abilities from which the evolution of human language may have arisen. The thesis starts with comparing human language with other communication systems. Then Chapter 2 addressed the question: what mechanisms are involved in learning a sequence of vocal items in zebra finches. Chapter 3 addressed whether zebra finches are able to discriminate between, and generalize, affixation patterns. Chapter 4 dealt with a controversial topic that is recently getting a lot of attention: whether animals show the ability to learn __algebraic__ rules that are relevant to syntax learning in humans. Chapter 5 examined the ability of zebra finch to learn nonadjacent dependency that is important for learning the hierarchical structure of languages. Altogether, this thesis provides positive evidence for similarities between humans and songbirds in using transitional information, generalizing surface transformations of human affixation patterns and detecting nonadjacent dependencies. Show less
Birdsong and human speech are both complex behaviours which show striking similarities mainly thought to be present in the area of development and learning. The most important parameters in human... Show moreBirdsong and human speech are both complex behaviours which show striking similarities mainly thought to be present in the area of development and learning. The most important parameters in human speech are vocal tract resonances, called formants. Different formant patterns characterize different vowels and are produced by moving articulators such as tongue and lips. However, not much is known about the production and perception of vocal tract resonances by birds. In this thesis I show that both songbirds and parrots use different articulators, comparable to humans, to modify the sound produced. While in songbirds beak gape and the expansion of the oropharyngeal-esophageal cavity are the most important articulators, parrots exhibit prominent tongue movements which also might explain their sophisticated ability to mimic human speech. Regarding formant perception I show that zebra finches can discriminate human words differing only in their vowels and categorize these words independent of speaker identity. To do so the birds employ, just like humans, a combination of intrinsic and extrinsic speaker normalization. Furthermore, when tested for a cue weighting bias both zebra finches and Dutch adults weight higher frequencies stronger. These results indicate that the mechanisms underlying vocal production and perception in birds and humans exhibit more similarities than realized before and studying birdsong will increase our knowledge about the emergence of these mechanisms and might even shed light on the evolution of human speech. Show less
