Conservation of shore birds using smell as a misinformation tactic

by Hinal Kharva: The effect of misinformation can bring a lot of trouble for human society. All animals try to make better choices using accurate information. However, this new study from New Zealand in Science Advances provides a new perspective on using misinformation as a tactic in saving endangered bird species.

In New Zealand, the predation by invasive species like ferrets, cats, hedgehogs, and rats has been observed since the time these animals were introduced around 1800.  These predators search and hunt the shore birds by the odours released from feathers and eggs.  The shorebirds such as banded dotterel, plovers, wry bill and the South Island pied oystercatcher build camouflaged nests with pebbles available around riverbeds during their breeding season. Unfortunately, the camouflage fails to provide protection, as these invasive predators rely on the sense of smell.  Several control techniques such as baiting, trapping didn’t really help with conservation of native endangered species. There are also animal ethics problems in using lethal techniques.  The cost of these techniques is also really high.  In contrast, the new study provides a novel approach for the conservation of endangered shore birds.

The study was conducted at New Zealand’s South Island, an open braided river ecosystem of the Mackenzie basin in the south Canterbury region.  The scientists, Dr Norbury and his collaborators, have been studying this for almost ten years. To begin with, they extracted odours from the feathers and preen glands of three different bird species, Chicken, Japanese quil, and Kelp gull. They mixed the odours from different birds and created a generalized form, so the resultant odour was not species-specific.  To the human nose, it smells like you are visiting an aviary.  These odours were applied to rocks around the area covering 2000 hectare at the river sites, 5 weeks before and during nesting time of the shorebirds. They applied the odour every three days almost around three months. They also set up the camera traps at 40 different sites at a time to monitor the nest.

The given figure gives the idea about the study site, the native birds, predators, which are found at the site and the methods used by researchers to conduct the study.

Figure 1. The study area showing the study species (predators and native ground-nesting birds), the experimental design with treatments reversed at each of the four sites each year, and the scale of the deployment of the 300 to 400 odour points at each site. Photo credits (background images): Grant Norbury, Manaaki Whenua–Land care Research (Norbury et al 2021)

Let’s look at what they found.  In 2016, once the fake odour was applied, the predators were attracted by the smell for the first few days but soon they lost interest as they learned that these odours don’t help with finding food. Eventually they stopped searching for the prey at the odour treated sites.  Once the shore birds arrived for nesting, the results were surprising, as predators continued to avoid those odour-treated areas.  On the other hand, control sites (without odour treatment) exhibited predation of eggs as before.  During the course of this experiment, odour-treated nesting sites showed that nest destruction was nearly halved and chick production was almost 1.7 times higher compared to control sites. In 2017, they repeated this experiment by flipping the control site as a treatment and the similar result was observed.  They also used a model to identify the success of this fake-odour tactic, which suggests that the population of one of the shore bird species, plover populations, would increase around 75% over 25 years. On the contrary, without this tactic the population of these birds may decline more than 40%.

To conclude, manipulation of the sensory cues used by predators provided great benefits to the vulnerable prey species. This innovative method opens up new opportunities for conservation of native animal species without having any direct interaction with animals. It also rules out the ethical problem associated with the cost and lethal practices used for invasive predators.

Here is the link to watch this research work: https://youtu.be/PLOy-bdhSBg

Reference:

  1. Norbury G. L, Price C.J, Latham M. C, Brown S. J, Latham A.D.M, Gretchen E. Brownstein G. E, Ricardo H. C, McArthur N.J, and Banks P.B (2021) Misinformation tactics protect rare birds from problem predators, Science Advances 7:eabe4164 | doi:10.1126/sciadv.abe4164
  2. Price c. J, Banks P.B (2012), Exploiting olfactory learning in alien rats to protect birds’ eggs. Proc. Natl. Acad. Sci. U.S.A 109, 19304–19309. Doi:10.1073/pnas.1210981109
  3. Blog by Jason Junior Grrl Scintist, March 12 (2021) Using ‘Fake News’ To Protect Vulnerable Breeding Shorebirds
  4. Blog by Condervation.com, March 11 (2021) Scientists used ‘fake news’ to stop predators killing endangered birds — and the result was remarkable

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