By Enzo Rodriguez-Reyes
Supporting local initiatives of conservation, such as, predator control programs, reforestation in regional parks, planting native trees in your backyard and keeping your cat indoors can make a huge difference for our native birds.
Hiking or walking in your local regional park is one of the most effective ways to escape our busy day to day lifestyle. Spending time in nature is known to bring benefits to wellbeing. An experimental study at a nature park in Colorado1 used playback to simulate high bird richness and found that hikers experienced higher levels of psychological restorative effects when the speakers were on than when the speakers were off.
For an outsider who moved from the tropics and is used to the rainforest hubbub, the lush New Zealand Forest seems a bit quiet. This is not only due to the difference in birdsong richness and diversity between New Zealand and the Latin-American rainforest but is rather by the impact of invasive species on the endemic birds. But in fenced nature reserves or offshore islands in New Zealand offer a completely different world full of life and sounds that made me wonder how New Zealand was before introduced invasive predators.
New Zealand is not an isolated case. A recent study published in Nature Communications2 found that the soundscape (fancy world for birds’ song) has been decreasing during the last 25 years in North America and Europe. Researchers across the continents used a mix of scientific data and citizen science to create a temporal comparison. Researchers used recordings from a popular online bird song library (Xeno Canto) to build historical soundscapes of 200,000 sites on both continents. They identified that since 1990 the soundscape diversity has deteriorated and become more homogeneous and quieter. Soundscape quality decreasing in both continents is associated with the global loss of biodiversity, the increase of urbanized areas, and human-related noise pollution, which makes it difficult for our capacity to perceive natural songs. Fewer birds out there plus more traffic noises explains why many of us wake up with a fake bird’s chorus alarm on the phone instead of a real one.
Adding to the decrease of bird populations and the increase of urbanization, there is another factor that might be contributing to the decreasing birdsong soundscape: cultural evolution. If you are asking yourself, do birds have culture? The answer is yes. Birds and other animals have cultures that are learned behaviours and vocalisations socially transmitted from one generation to another. Bird culture is very changeable, and these changes in culture can happen in short time frames and in entire regions3. Cultural evolution can negatively impact fragmented and small populations because the small number of individuals may not learn the original repertoire of the species, creating new versions of songs or maladaptive behaviours.
A clear example of this phenomenon is the Regent Honeyeater in Australia. Populations of the Regent honeyeater are declining across their habitat range and the species density is low in the areas where they are present. Juvenile Regent Honeyeaters that need to learn their typical honeyeater song cannot find enough adult birds to tutor them. So, juveniles are incorporating the song of other species into their repertoire4. Unfortunately, speaking “another language” isn’t an attractive quality for female Regent Honeyeaters, leaving those “polyglot birds” with fewer probabilities of reproducing, which in the end contribute to the decreasing population of the species.
Sadly, despite all the conservation efforts, the tendency of biodiversity loss is expected to be observed during the next decades, especially in highly urbanized areas like North America, which has lost 2.9 billion birds since 19705. In places like New Zealand, we can still revert some of this pattern as our species are mostly affected by invasive predators rather than the strong effect of urbanization. So, supporting local initiatives of conservation, such as, predator control programs, reforestation in regional parks, planting native trees in your backyard and keeping your cat indoors can make a huge difference for our native birds and extend to our wellbeing. The results are only starting to appear, where the city centre of Auckland has heard the song of the korimako (New Zealand bellbird)6 for the first time in more than hundreds of years, thanks to the efforts of local communities in predator control. Maybe in some years the songs of korimako and kokako may be common soundscapes in regular bush adventures again.
1 Ferraro, D. M., Miller, Z. D., Ferguson, L. A., Taff, B. D., Barber, J. R., Newman, P., & Francis, C. D. (2020). The phantom chorus: Birdsong boosts human well-being in protected areas. Proceedings of the Royal Society B, 287(1941), 20201811.
2 Morrison, C. A., Auniņš, A., Benkő, Z., Brotons, L., Chodkiewicz, T., Chylarecki, P., … & Butler, S. J. (2021). Bird population declines and species turnover are changing the acoustic properties of spring soundscapes. Nature Communications, 12(1), 1-12.
3 Otter, K. A., Mckenna, A., LaZerte, S. E., & Ramsay, S. M. (2020). Continent-wide shifts in song dialects of white-throated sparrows. Current Biology, 30(16), 3231-3235.
4 Crates, R., Langmore, N., Ranjard, L., Stojanovic, D., Rayner, L., Ingwersen, D., & Heinsohn, R. (2021). Loss of vocal culture and fitness costs in a critically endangered songbird. Proceedings of the Royal Society B, 288(1947), 20210225.
5 Rosenberg, K. V., Dokter, A. M., Blancher, P. J., Sauer, J. R., Smith, A. C., Smith, P. A., … & Marra, P. P. (2019). Decline of the North American avifauna. Science, 366(6461), 120-124.
6 Stuff (2021). Korimako/bellbirds spotted in Auckland for the first time in a century. https://www.stuff.co.nz/environment/126920618/korimakobellbirds-spotted-in-auckland-for-the-first-time-in-a-century
Enzo Rodriguez-Reyes is a Doctoral Candidate in the School of Natural and Computational Sciences at Massey University.
Disclaimer: The ideas expressed in this article reflect the author’s views and not necessarily the views of The Big Q.
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