Migratory species urgently need Humans’ help
Instead of doing what we can to protect dwindling populations of migratory birds, fish, sea mammals And wildlife that should be roaming far and wide, our activities are what is harming them the most. By
The first United Nations State of the World’s Migratory Species report states that some migratory species are improving, but nearly half (44%) are showing population declines, mainly attributed to human activities – overexploitation, habitat loss and anthropogenic climate change.
The report was launched on 12 February by the Convention on the Conservation of Migratory Species (CMS) of Wild Animals – a UN biodiversity treaty to which South Africa has been party since 1991.
“Migratory species rely on a variety of specific habitats at different times in their life cycles. They regularly travel, sometimes thousands of miles, to reach these places. They face enormous challenges and threats along the way as well as at their destinations where they breed or feed,” said CMS executive secretary Amy Fraenkel.
“When species cross national borders, their survival depends on the efforts of all countries in which they are found.”
Fraenkel said the landmark report will help to underpin much-needed policy actions to ensure the survival of migratory species, which provide vital benefits to humans by pollinating plants, transporting key nutrients, preying on pests and helping to store carbon.
The report shows the extent to which the decline in migratory species is being caused by human activities. Their two greatest threats are overexploitation (which includes unsustainable hunting, overfishing and the capture of non-target animals such as in
fisheries), and habitat loss, degradation and fragmentation (from activities such as agriculture and the expansion of transport and energy infrastructure).
But because humans are driving this looming crisis, they have the power to turn things around. Susan Lieberman, the Wildlife Conservation Society’s vice-president of international policy, said if the 133 governments party to the treaty did everything they had committed to do, the next report would have some good news.
Fish in danger
The most worrying finding from the report is that nearly all Cms-listed species of fish – including migratory sharks, rays and sturgeons – are facing a high risk of extinction, with their populations declining by 90% since the 1970s.
When species cross national borders, their survival depends on the efforts of all countries in
which they are found
Dr Ryan Daly, a marine scientist from the Oceanographic Research Institute in Durban, said because many sharks and rays live long, breed late and have few young, they cannot cope with the increasing pressure facing them from fishing, habitat loss, nursery loss (estuary degradation) and changes in food availability.
He added that many more migratory species along South Africa’s coast have become classified as endangered in our lifetime, such as the scalloped hammerhead, dusky shark and ragged-tooth shark. The sawfish has become extinct.
Fewer birds
More than three-quarters (78%) of the Cms-listed birds are categorised as being of least concern. However, the report says it’s important to note that there are large numbers of birds (134 species, or 14%) that are globally threatened.
Birdlife SA’S Flyway and Migrants Project manager, Jessica Wilmot, said South Africa’s migratory waders (waterbirds) are facing unprecedented threats, particularly along the west coast. Based on biannual waterbird counts, Birdlife SA has found that species such as the sanderling, ruddy turnstone, Cape cormorant and curlew sandpiper have dwindled in number.
Wilmot said studies have shown that many populations of long-distance migratory bird species have declined over the past 50 years, and their decline has been greater than that of resident species or short-distance migrants.
She said there are numerous general threats found on their migratory route and at their overwintering sites. These include destruction (loss of wetlands or suitable habitat), prey-based depletion, persecution (shooting, trapping, poisoning), unintentional poisoning, electrocution or collision with energy infrastructure, and killing for food and belief-based uses.
Whales recovering
Many whale species have seen increases in their populations since the introduction of protections from commercial whaling.
For example, the report states that the humpback whale has been increasing at a global level. The species is now categorised as being of least concern with an estimated global population of more than 80,000 mature individuals.
Dr Els Vermeulen, research manager of the Mammal Research Institute Whale Unit at the University of Pretoria, said the largest threat to migratory baleen whales (species
that migrate close to shore, such as southern right whales and humpback whales) around southern Africa relates to shipping and underwater noise pollution. Climate change is also impacting their food availability in the Southern Ocean.
Habitat loss and climate change
The two greatest threats to Cms-listed and all migratory species are overexploitation and habitat loss because of human activity, the report states. Climate change, pollution and invasive species are also having profound impacts on migratory species.
Wilmot said habitat loss and overexploitation are intensifying, exacerbated by climate change. “The most important factor is retaining suitable habitat throughout the migration route,” she said.
“Recent tracking studies have revealed that several species wintering in southern Africa pass through western Africa on their spring migration route. This emphasises the importance of ensuring areas within western Africa are protected to support these species by providing resources, whether that’s food or a place to rest.”
Closer to home, the shark nets in Kwazulu-natal are adding to the pressure from commercial fishing. The loss of function in some key nursery areas like St Lucia also adds to it.
Vermeulen said toothed migratory cetacean species such as killer whales, beaked whales and sperm whales are affected by anthropogenic pressures related to fishing pressure, as well as noise, chemical pollution and shipping lanes.
In terms of climate change, the report states that increasing temperatures will result in “changes in precipitation, extreme weather, sea level rise and ocean acidification, all of which have the potential to dramatically change habitats and their species composition”.
Daly said climate change may cause intense heatwaves followed by upwelling events where the temperature drops suddenly, which can result in migratory sharks being stranded in water too cold to survive.
Vermeulen said effects on sea ice are being seen, which has “detrimental effects on the recruitment of Antarctic krill, the key species of the Antarctic food web. This in turn has effects on baleen whale foraging abilities and therefore reproduction.”
Ecological corridors
Wildlife or ecological corridors connect wildlife populations that would be disconnected by human structures or activity.
Rhian Berning, CEO at the Eden to Addo Corridor Initiative, which aims to link ecologically important areas, said: “Here in South Africa we have a legacy of fortress conservation where protected areas are heavily fenced off, creating barriers to natural movement and migration.
“Just for a moment, cast your mind back to imagine the phenomenal migrations that must have coursed through our country – elephant, springbok, zebra, all moving in their thousands.
“And while we can’t necessarily restore those major migrations, we can enable connectivity again between protected areas and areas of ecological significance – nature corridors that allow these essential life-giving processes to flow again as birds, mammals and reptiles move with the seasons, especially in the face of a changing climate.”
What should the government do?
The report is a clear wake-up call and provides a set of priority recommendations for action. These include:
Strengthen and expand efforts to tackle the illegal and unsustainable taking of migratory species, as well as incidental capture of non-target species;
Increase actions to identify, protect, connect and effectively manage important sites for migratory species;
Urgently address those species in most danger of extinction, including nearly all the Cms-listed fish species; and
Scale up efforts to tackle climate change as well as light, noise, chemical and plastic pollution.
Inger Andersen, executive director of the UN Environment Programme, said the report “clearly shows us that unsustainable human activities are jeopardising the future of migratory species”.
“We cannot afford to delay and must work together to make the recommendations a reality,” she said.