Abstract
Human settlements and activities alter the natural environment acoustically and visually. Traffic noise and street lights are two of the most prominent pollutants which may affect animal activity patterns. Birds in urban areas have been reported to sing nocturnally and to have an earlier dawn chorus compared to their rural counterparts. However, few studies have measured whether singing more at night or earlier in the morning means singing less during daytime. It is therefore unclear whether they shift or extend or overall increase their activities. Furthermore, few studies on anthropogenic noise related shifts in song activity replicated well at the habitat level. We recorded singing activity in urban and rural great tits (Parus major) for 24 hours and sampled eleven urban-rural pairs of territories, inside and outside eleven different cities across the Netherlands. We found that urban birds sing earlier during the day, have similar singing effort in the dawn chorus, but sing less than rural birds during the rest of the day. The shift in timing between urban and rural birds was 22 minutes on average and resulted in more songs for urban birds during a less noisy time of the day. The lower singing activity over the day made that urban birds sang less when it was more noisy compared to the natural rhythm of rural great tits. We currently lack insight into whether these differences yield any positive or negative fitness consequences, but it is a clear case of how anthropogenic effects on the natural environment influence fundamental aspects of daily life in the animal communities with which we share the urban habitat.
Highlights
Activity patterns are species-specific, typically driven by natural environmental and social cues (Aide et al, 2013; Frey et al, 2017), but can be affected by human disturbance (Barrueto et al, 2014; Lendrum et al, 2017; Gaynor et al, 2018)
Note that differences in dawn chorus start were more consistent than duration differences, the latter of which were more variable, for example ranging from 20 min until 160 min for urban birds (Figure 3B)
We were able to show that urban birds started earlier, but that this does not affected how much they sang in the same hour bins during the dawn chorus compared to rural birds
Summary
Activity patterns are species-specific, typically driven by natural environmental and social cues (Aide et al, 2013; Frey et al, 2017), but can be affected by human disturbance (Barrueto et al, 2014; Lendrum et al, 2017; Gaynor et al, 2018). Others nocturnal, and many have crepuscular peaks of activity around dawn or dusk These labels are typically based on activity biases in foraging, nest building, or moving around, but may apply to preference period for vocal activity. Many mammals are naturally most active at night (Frey et al, 2017; Ogurtsov et al, 2018), but there are reports on species that are diurnal in undisturbed areas and nocturnal where human are active or noisy during daytime (e.g., Martin et al, 2010; Marchand et al, 2014). The nature of this shift is still not well understood as few studies on avian vocal activity patterns replicated well at the level of the habitat and few studies collected detailed data across the 24 h of a full day
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