Written by Katy Ellis. As an Ecology student, I am interested in how the planet’s organisms interact with one another and their environment. Understanding the ecology of something, be it bird, bush or beetle, is vital if we are to inspire people in the importance of protecting it.
Though marine and terrestrial ecosystems are intrinsically interdependent, there is little research dedicated to the coastal and intertidal habitats that form the intersection of these two environments. Curlews, like most waterbirds, spend different stages of their lives in different habitats, wintering on estuaries and mudflats but choosing to migrate to farmland, meadows and marshes to breed in summer. Despite the fact that wading birds are central to the maintenance and health of these ecosystems, they are often left out of wetland ecology research.
“Ecosystem services” is the collective term given to the varied ways in which humans benefit from nature and healthy ecosystems. They help us quantify their importance and therefore argue more effectively for their protection. As well as the biological roles of organisms, they also include their value to human society and culture.
Historically curlews provisioned people with down and meat thanks to their former abundance. It was this reliance on curlews that helped bolster the human reverence of waterbirds across Britain and the rest of Europe. Today Scotland still enjoys revenue from biophilic tourism born of the Vikings’ relationship with swans.
Curlews themselves hold importance as a flagship species in conservation education. Their soprano cry is an icon of the natural British soundscape and has inspired copious naturalists, authors and poets alike.
Culture aside, curlews provide many benefits from a biological perspective. They can be a form of low-cost monitoring as bioindicators as they are easy to spot and count. From a curlew population you can infer information on other species’ populations that are less visible; though more research needs to be done, curlews can be indicators of aquatic diversity in estuaries, invertebrate diversity, species richness of plants (ie how many different species of plants there are in an area), soil health and nutrient status. A low population of curlews in an otherwise seemingly suitable habitat for example may suggest a high population of predatory foxes or low populations of invertebrates upon which curlews feed. Analysis of their feathers can even be used to monitor levels of polluting chemicals in water supplies.
Curlews can also indicate diseases and help us monitor their spread. As potential carriers of several infections, curlew surveillance could help epidemiologists understand the geographic spread and infection dynamics of zoonotic diseases (diseases which can be passed from animals to humans). Waterbirds more generally can even control pests themselves as they are major predators of aquatic insect larvae, such as Chironomidae (lake flies) which can prove to be crop pests.
Moreover, when they dig around in soil and mud in search of small invertebrates to eat, they alter the distribution of sediments, a process known as bioturbation. This in turn broadens the diversity of plants, providing habitats for a diverse range of wildlife, and increases the ecological stability of mudflats. Mudflats are a vital natural defence as they help to dissipate energy from incoming waves and tides, protecting us from flooding and rising sea levels. These habitats not only look beautiful, but are critical for coastal communities who are at the forefront of effects of climate change.
When it comes to feeding our growing population, it is well known that seabird guano makes excellent agricultural fertilizer. The same can be said for wading birds including curlews, who move nutrients around as faeces. Their seasonal migration between wetlands and uplands mean they have important roles in balancing soil chemistry and nutrient cycles in different habitats across the country.
This biogeochemical cycling, or circulation of essential chemical nutrients, hugely increases the primary productivity of wetlands by supporting photosynthetic algal species such as charophytes. These algae supply oxygen to the atmosphere and ensure the continuation of human health, agriculture and economies.
As well as distributing chemical nutrients, curlews also disperse seeds, invertebrates and beneficial microbes which stick to their feathers, feet and bills. This dispersal of organisms maintains connectivity between ecological communities and ecosystems, preserving species and genetic diversity, which in turn safeguards wider biodiversity.
The World Economic Forum cites biodiversity, the variety of life on Earth, as essential to our physical and mental wellbeing, medical research, food security and global business. With critical habitat loss worldwide, migrating birds such as the curlew may be one of our best hopes in saving our planet, wild places and human society.
Katy Ellis is studying a BSc in Conservation Biology & Ecology at Exeter University.
As of 11th May, she’ll be walking 300 miles along the Essex, Suffolk and Norfolk coasts to engage coastal communities in marine science and conservation. As well as giving talks en route, she will be assessing the ecology of East Anglia’s coastline from the ground and finding out more about our marine wildlife such as curlews. Follow her adventure here: Language of Conservation: Walking England’s East Coast (facebook.com)