Human Expansion And Its Effects On Wildlife
Whether driving along the highway or hurrying back home through dark alleyways, we all have undoubtedly seen how wild animals interact with our human-made structures and systems. From curious deer poking at separation fences to raccoons and foxes rummaging through our garbage, the effect is clear – as we humans expand our infrastructure, wildlife are increasingly finding themselves in adapt-or-perish situations.
Via urbanization, more and more animals encounter our presence and often end up altering their behaviors to accommodate for the invasion of space or time. In this blog post, we consider some of the more obvious effects on wildlife ethology and the way they organize themselves socially, and discuss what should and can be done to alleviate our negative impact on nature.
Just last year, a group of scientists characterized the way we affect wildlife as oncogenic, meaning that it causes or generates cancer. In fact, there are several human-made impacts that seemingly increase cancer prevalence in wild animals.
Of course, human activity causing cancer is nothing new. According to the WHO, cancer is the second leading cause of death among humans themselves. It’s something nearly every person has been affected by, whether directly or indirectly, and many of us can relate to its horrible effects on health and societal well-being.
Meanwhile, the paper mentioned above links habitat pollution, loss of genetic diversity and inbreeding, light pollution, and human-sourced food as potentially leading to increased incidence of cancer in wildlife. These findings illustrate the breadth of humans’ impacts. Habitat pollution is the most straightforward – our litter and whatever else ends up in nature may contain chemical compounds that are directly toxic and carcinogenic. Just last year, a group of scientists found that all tested marine turtles had ingested microplastics. The other three factors, however, are a bit less straightforward and deserve some extra exploration.
One of the first things that comes to mind when thinking about how urbanization influences wildlife populations is movement restriction. Our widespread infrastructure of cities, highways, motorways, railways, and pathways divide and fragment nature into a mosaic of sorts. Often, when enforced by safety fencing, this subdivision leads to splitting of animal herds, packs, and groups.
Many researchers have looked at this phenomenon; in one study, a large cohort of scientists led a project aiming to show that the human footprint in natural ecosystems reduces wild mammal movements. They found that the effect is not subtle: individual mobility of animals living in highly impacted areas showed a threefold reduction. The researchers attributed the effects to habitat change and fragmentation via physical movement barriers, and food and water availability via human sources.
This impact of ours is especially worrying because it’s one that cannot be reversed or eliminated. Our infrastructure has been growing steadily and shows no signs of slowing down. Will our continuous demand for growth and expanse push wildlife further and further to the margins? Animal advocates are surely inclined to find effective measures to combat negative effects wild animals face in the anthropocene.
One recent review looked at how wild mammals are starting to avoid us temporally, too. Apparently, in places of human-wildlife co-habitation, where finding spatial refuge from us might be tricky, mammals start to change their behaviors in terms of time – their nocturnal activity is on the rise. Although little is known about the long-term influence of human disturbance on wildlife nocturnality, the mere fact that animals are changing their temporal habits to avoid us gives some merit to the idea that they’re afraid, and we should try to reduce this fear that we instill.
Yet another field of study that has recently benefited from quality research is the impact of human-made noises in marine environments. Three studies from our library can help to illustrate the scope of this issue:
- A group of scientists showed that oysters do react to sounds and are indeed sensitive to sound frequencies which emanate from shipping boats and other crafts. Since it is believed that bivalves regulate their spawning events when triggered by aural cues, our noise making in the seas may affect the reproductive cycles of these animals directly.
- Scientists investigated the effect of boat noise on the embryonic development and survival of mollusks, finding that such noises increased the likelihood of suffering at the embryonic stage and mortality at the early free-swimming stage. This suggests that our presence in the sea may have detrimental fitness consequences early in life for species playing crucial roles in coral-algae dynamics.
- Researchers warn about ever-increasing anthropogenic noise levels in marine ecosystems and highlight that there is a pressing need to better understand the role anthropogenic sound plays in the disruption of acoustic communication within marine environments. Their work showed that marine fishes have troubles communicating effectively and essentially end up “shouting” into empty space in attempts to find others.
Be it through our daily hustle and bustle, or excessive traffic from noisy boats, we change wildlife behavior. Now, animals have to adapt to our presence and everything that comes along with it. Although yet unknown, the effect our invasions into the natural have may be dramatic in the long run.
Changes In Dietary Preferences
As more of a specific type of altered behavior, many species of wildlife undergo dietary changes as a direct consequence of urbanization. A group of scientists studied finches in the Galapagos islands to show that human presence changes their diets and human-oriented behaviors – the birds approached people much more readily in highly populated and visited areas. The birds were found to develop a preference for processed human foods once exposed to it, too! The researchers suggest that this ethological change may have dire consequences for both the well-being of the individuals and the fate of the species due to negative health and physiological effects from highly processed foods, and suppressed ecological and evolutionary processes which promote species and phenotypic diversification.
Although the researchers did conclude that this impact is driven by human behavior and is not an inevitability, it’s still hard to imagine that we would be able to eliminate both intentional and inadvertent feeding of wildlife – the driving force behind such changes.
What Can We Do?
It certainly does seem that Earth will play host to our urban expansion for many years to come. Where does that leave wildlife, though? With our numerous alterations of nature and interactions with the animals themselves, they are obviously struggling to keep away as much as they may want to. Scientists estimate that we’ve already modified 50-70% of the planet’s land surface. Continuous expansion and its unavoidable effects on nature and wildlife will likely reduce the amount of existing wild animals. How many can possibly survive in the ever-shrinking wilderness, after all?
Researchers are united – we need more knowledge on the long-term effects of our expansion. Should we learn that our disturbances do indeed threaten species survival, serious action will have to be taken in order to conserve biodiversity and reduce wildlife suffering. Recommendations already range from ensuring landscape permeability in terms of sustaining animal mobility and establishing temporal (time) regulations in protected areas to halt species’ shifts towards higher nocturnality.
Whatever the strategy, animals would surely benefit from an active combination of observational studies, their findings, and computer modeling – a powerful technique enabling researchers to run large numbers of simulations to reveal the best potential conservation methods. Furthermore, who knows what benefits employing artificial intelligence neural networks could reap.
On the flip side, we have already given protected area (PA) status to many regions around the world. It is essential that these PAs are sustained and used as positive models for including more and more areas under the conservation umbrella. Researchers show that PA management, although quite expensive, is an economically significant activity, generating $600 billion USD a year in direct in-country expenditure alone, and attracting 8 billion visitors worldwide a year. The net positive economics of PAs surely generate incentives on governmental levels.
Striving for more PAs while there is still wilderness to create them in, can help ensure more human-free zones, providing wild animals with spatial and temporal buffers and safe havens. However, several years ago, a group of scientists found that improvements are necessary specifically in marine PA design and regulation enforcement to result in high conservation efficacy. In other words, just having a lot of marine PAs cannot be regarded as an indicator of success alone.
Animal advocates might feel slightly disappointed to learn that there is often little that can be done to help wild animals who do not attain protected status. For those who want to actively contribute to the growing pool of knowledge, becoming citizen scientists may well be the way to go! Citizen science encompasses projects which engage both scientists and non-specialists in the processes of gathering, evaluating or computing scientific data. Several successful examples of such collaboration have already been outlined in a blog post elsewhere on Faunalytics. Otherwise, our best bet at protecting wildlife from some of the unavoidable consequences of urbanization may well be advocating for PA expansion, improvement and creation.
Where does this leave wildlife currently struggling in the anthropocene? Now might actually be the time and place for wildlife veterinary sciences to accelerate. Raising concerns about wild animal well-being issues that we cause might be a clever approach advocates can use to help motivate more people to specialize in this rather overlooked field, and allocate funds towards alleviating human-made impacts.