Header photo: Black headed gulls in Kunming China (photo by: Charrine Liu Wikimedia commons).
Feng C, Liang W. 2020. Behavioral responses of black-headed gulls(Chroicocephalus ridibundus) to artificial provisioning in China. Glob Ecol Conserv. 21. doi:10.1016/j.gecco.2019.e00873
To feed or not to feed wildlife
Bird feeding can be an important cultural activity where we connect with wildlife. As a child I remember going to the town plaza and buying corn kernels to feed the pigeons. It was exhilarating to be surrounded by so many birds. I imagine many of us have had a similar introduction to wildlife. Additionally, many vulnerable birds species benefit from access to food, especially during the winter when natural food sources as scarce. However, scientists have been deliberating whether there could be long term negative effects associated with human feeding. A negative consequence of human feeding is an agglomeration of many individuals in small areas which could aid disease transmission. Also, as birds rely on the food we provide, they may abandon natural prey decreasing a birds’ fitness and potentially leading to cascading effects due to perturbations of the natural food web.
Black headed seagulls in China
Figure 1: (A) Black headed gull flocking around humans feeding directly from their hands. (B) Dr. Changzhang Feng seen here with a gull that perched on his head to beg for food. Black plumage in the head is typically seen in summer and not in the winter as shown here. (Images supplied by author as supplementary materials of the publication which is open access).
Because human feeding has become so prevalent, it is important to monitor its effect on wildlife to decide when and how these activities should be managed. The author of this study, Dr. Changzhang Feng (Hainan Normal University, expert in wildlife ecology and conservation biology) chose to study the black headed gull (Chroicocephalus ridibundus) along a rural-to urban gradient in southern China (figure 1). The black headed gull is the most commonly observed gull in southern China during winter. These birds started visiting Kunming city around 1985 and since then several thousand gulls visit parks every winter to eat human food. Natural populations of the gulls rely on insects, small fish, prawn, and mollusks for food. In the city some gulls have become dependent on human food
To explore whether human feeding influenced their foraging behaviors, the team measured the proximity of birds to humans when they ate (foraging distance) and the distance at which the bird fled from a slowly approaching observer (flight initiation distance). When birds are typically fed straight out of a human’s hand you would expect to find small foraging distances (follow link to video by Dr. Feng provided in the publication). Similarly, birds should have shorter flight initiation distances when they are tolerant of humans and initiate flight at greater distances when they are intolerant of humans.
Winter buffet in China
Dr. Feng and his team found that gulls in urban areas had very small feeding distances from humans (Figure 3). This is because most birds ate directly from the palm of humans. Park visitors at the urban sites had access to vendors specifically dedicated to selling treats to offer the many gulls that visit over the winter. Rural sites were less frequented by people and also had fewer or no instances of human feeding. At these sites, birds ate at greater distances away from humans. Similarly, the researchers found that birds were more tolerable to the approach of humans at urban sites (Figure 4). The findings suggest that urban birds are very tolerant of humans. This means either this behavior is evolving in urban sites or that only tolerant (bold) birds are able to exploit feeding opportunities in these sites.
Eating your way to domestication
The results of this study suggest that gulls in rural areas still view humans as potential threats and maintain wariness when exploring feeding opportunities. In contrast, urban birds are treating humans more like caretakers and rely heavily on food provided by them. In fact, the author reports that birds in Kunming city tend to beg for food. Researchers worry that this could be evidence of an unintentional domestication. This means that urban birds are eliminating behavioral characteristics associated with fear. For example, as birds become hypertolerant to humans they could become emboldened and erode their ability to be vigilant of predators. Gulls could also could break away from their natural migration patterns and become permanent residents at these parks. This could lead to birds becoming a nuisance or a pests as their numbers increase. A similar case happened in the United States with Canadian Geese (Branta canadensis) A potential solution is to shift to birds feeders to dissociate humans with food. The food quantity and feeding period should be closely managed so that these birds do not become permanent residents in these parks.
Should you feed wildlife?
Access to human provisioning can be an important conservation strategy for many animals that have a hard time finding food due to drastic habitat reduction, like urbanization or deforestation. However, you should always feed animals food that they would typically eat in the wild and never processed human food which could be too starchy for their digestive systems. Wild animals should not associate humans with food. If you choose to feed wild animals, always use feeders that animals can exploit at a healthy distance from any humans. This can help abate increased tolerance to humans and help maintain wariness typically seen in more natural sites.