Washed out: Where are the animals?

During times of storms and flooding people rarely think about animals. They too have been washed away, forced to relocate or had their homes flooded. It’s not something that makes the news but it is important for conservation purposes to understand what exactly goes on with wildlife during flooding.

Flooding usually leads to a polluted water supply, normally lead pollution and the release of toxic hydrogen sulphide fumes. This means that many animals, often farm animals living on nearby fields, consume the toxic water and are poisoned. The problem with this sort of issue is that it is impossible to quantify the effects. We often hear that “x” amount of sheep were found dead due to poisoned water but we don’t tend to hear about it when animals like deer, badgers and foxes are found dead.

Larger mammals such as foxes and badgers are also affected by the floodwater but can often escape as both are strong swimmers and climbers. That being said there have been occasions when humans have rescued these animals during floods and a charity warned that flooding had possibly damaged badger populations in Gloucestershire in 2014. A lack of monitoring though means that we have little idea of how serious the issue is.

Unsurprisingly, ground or water dwelling animals are suffering, notably hedgehogs, bees, water voles, earthworms and otters. Anything that can’t escape the floodwater will be washed away or forced into the open where they are predated upon. Water voles and hedgehogs in particular are a worry as their populations are suffering and a yearly “flood cull” is not doing them any favours. People are often surprised that water voles are threatened by flooding but they live in burrows in the riverbanks that become either eroded away or submerged in floodwater. That being said, water voles can sometimes benefit from floods if they survive. In 2013  it was found that water voles were much more widely distributed after the floods than before which appears to have benefited the population. It is unclear if the water voles deliberately used the fast flowing water to travel to new territories or if they were simply survivors who were deposited in new areas.

Are water voles helped or hindered by rising water levels?

Are water voles helped or hindered by rising water levels?

What about birds? Inland birds can suffer due to a lack of food but are less affected than many animals as they can often scavenge or feed on the insects flushed out by the floodwater. Some birds of prey can cope with scavenging but for others the rain proves difficult. Barn owls in particular don’t tend to hunt in the rain as wet plumage makes it difficult for them to fly.

Seabirds tend to be some of the worst affected birds. Around 600 seabirds were found dead on the coast of England during last years storms, with a further 11,000 washed up on the French coast due to the tides. Seabirds are affected due to strong winds blowing them off course and causing rough sea conditions which prevents hunting. This causes seabirds to suffer from dehydration as their water comes from their food and dehydration will affect most before hunger will.

Marine mammals such as seals are affected although most of this year’s seal pups will have moulted and gone to sea by the time the storms hit which should make them more likely to survive than if the storms had come a few weeks earlier. Even adult populations can be at risk though as 250 seals were found dead in the Southwest corner of England after last years storms. Most had drowned or died of exhaustion from fighting the strong tidal surges. This year the floods have, so far, been more to do with rainfall than with extended periods of high winds and so seal and seabird populations should fare better than in the past.

The effects of the flood are often felt the year afterwards. Species like salmon lay their eggs in rivers and if floods wash the eggs away then the number of hatching fish declines the following year. This then affects both the species that salmon eat and the species that eat them. Young fish are often a key link in aquatic food chains and their removal has a corresponding impact up the chain. Multi species interactions such as this are notoriously difficult to predict though the effects are likely to be negative and damaging to the environment in most cases.

There are some upsides of flooding though, floodwater often results in the dispersal of plants to higher areas and carries seeds to new places. This does however mean the spread of invasive species like Himalayan Balsam as well as natives. Several species of water snail also rely on flooding in order to move to new areas and so rely on flooding for their survival.

As floodwaters subside aquatic birds have a field day feasting in the new wetland areas that developed and are often seen probing the soft ground for insects. Many birds that will usually feed in rivers instead feed on the temporarily submerged floodplains (assuming we haven’t built on them) where shallow water makes for easy hunting. Most birds tend to drift towards flooded fields and temporary ponds where the water is not fast moving. These new habitats benefit them as it is far more difficult for foxes or other predators to sneak up on groups of birds here than on riverbanks.

 

Snipe don't seem to mind ther new hunting grounds

Snipe don’t seem to mind ther new hunting grounds

 

Flooding is generally negative to animals though many adapt quickly to it and use it to their advantage where possible. As always though if you see a stranded animal you should report it to your local wildlife agency who should be able to deal with it.

 

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Scott Thomson
Recent ecology and conservation graduate. My blog is here https://wildchatblog.wordpress.com/
Scott Thomson

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