This blog post is provided by Bar-Ziv Michael, Sofer Aran, Gorovoy Adel and Spiegel Orr and tells the #StoryBehindthePaper for the paper “Beyond simple habituation: Anthropogenic habitats influence the escape behavior of spur-winged lapwings in response to both human and non-human threats“, which was recently published in Journal of Animal Ecology. In their paper they use a unique “Jack-Truck” to simulate a jackal predator, and explore how lapwings respond to novel predators and humans.
לחצו כאן בשביל הבלוג בשפה העברית
Spur-winged lapwings (Vanellus spinosus) are monogamous birds that tend to stay with their partner all year round. During the breeding season they guard their nest and chicks with intimidating calls, attacking everything that get close with sharp spurs located on their wings. This species is considered to be one of the most common waders in Israel, and can be found in a variety of habitats, including natural habitats, as well as dense cities. This fact is quite surprising, considering that wader populations are declining worldwide due to the fact that they nest on the ground. Natural habitats across the world are being destroyed to make way for human needs, which in turn negatively affect a large number of species that cannot cope with the changes. Lapwings, on the other hand, not only represent a growing population, but they are also found to be able to nest and raise their chicks into adulthood in parks and even next to highways.
While some lapwings prefer to live next to human settlements, not all of them do. Most of the lapwings stay in more natural areas with fewer encounters with humans. Wild animals that live in proximity to humans usually present a bolder set of behaviors, which differ from populations of the same species that live in a more natural habitat. Those bolder responses can be a result of fear reduction toward humans (in other words, habituation to an urban environments), or alternatively present a larger effect that the urban environment creates (for example individuals with bolder personality reside in more urban settings).
A simple and well-known method to test boldness in field conditions is testing the animal’s flight initiation distance behaviour (or FID). Generally, animals that escape too early from an approaching threat will not be able to fully exploit their environment, while on the other hand those that are escaping too late might be at risk of getting caught by a predator. The behaviours animals present after their initial escapes are important as well, because more lethal predators may require a faster reaction, fleeing further away and finding a place to hide. Different predators also require different escape strategies, and while with one type of threat it is worthwhile escaping fast and far, in others it can be a burden. Those strategies can also differ between habitat types, for example, in urban settings individuals that are too scared and will flee from every person passing by, won’t be able to exploit this habitat properly and might prefer to forage in other areas.
In a recent paper in the Journal of Animal Ecology, we tested the escape behaviour of spur-winged lapwings. More specifically, we first looked at their flight initiation distance, their mode of escaping (by foot or flight), and finally what distance they fled. We tested those behaviors between three habitat types (human-dominated, water ponds, and fields), and compared them to two kinds of approaching predators (a human and a jackal). While humans are abundant in urban settings, jackals tend to be found in natural environments. Jackals also prey on lapwing nests, chicks, and potentially also on the adults. To mimic an approaching jackal, we used a taxidermy of a young jackal mounted on top of a camouflaged, off-road remotely controlled vehicle (named “Jack-Truck”). To find lapwings in the different environments, we searched for them while driving. We choose this strategy because lapwings tend to be less alert to driving vehicles, which made it easy to notice them without disturbing them. Once a lapwing was spotted, they were approached by a human, or a jackal and the escape sequences mentioned above were recorded.
The purpose of this experiment was to understand 1) if individuals found in urban setting show a general bolder response to approaching threats when compared to other habitats? And 2) if so, does this bolder response derive from simple habituation to humans, or does it represent a larger phenomenon (such as human settlements attracting generally bolder individuals)? If lapwings showed a stronger reaction to the jackal compared to a human in human-dominated environments it might hint towards habituation, because they were more afraid of a novel predator. On the other hand, having the same reaction to both predator types might suggest a deeper effect those habitats have over these animals.
Examining our first question, we found that lapwings from human-dominated habitats were bolder in most of the sequences of the escaping behavior. First, as expected, they presented a shorter FID when approached. Secondly, even after escaping they still presented bolder behaviors by fleeing to a shorter distance and more likely to escape by running (rather than flying). Interestingly, when considering our second question, we found that lapwings tested in human-dominant habitats presented a bolder respond to both a human as well as a jackal approaching. Those results show that lapwings not only present a bolder behavior in human settlements, but more importantly, it shows that habituation to humans cannot be the only explanation for the bolder response.
Those results can give us a hint of the effects human disturbance have on animals. Our paper shows that some individuals can become accustomed to human settlements, but it has a cost. To do so, they will need to reduce their fear response. This can be a dangerous strategy, because while most people will not try to harm them, once a more lethal predator approaches them, it could be more difficult for them to avoid this situation. In a fast-changing world that is becoming more urbanized, findings like these are essential for understanding the impact human-development has on wildlife populations and communities, even in species that at a first glance appear more resilient to those changes.
Read the paper
Read the full paper here: Bar-Ziv, M., Sofer, A., Gorovoy, A., & Spiegel, O. (2022). Beyond simple habituation: Anthropogenic habitats influence the escape behaviour of spur-winged lapwings in response to both human and non-human threats. Journal of Animal Ecology, 00, 1– 13. https://doi.org/10.1111/1365-2656.13858