Drought threatens California wildlife

Animals often found in wetlands like flooded fields have no alternative but to look elsewhere for food and water as their habitats dry up.

The waterfowl breeding population in California in 2013 was estimated at about 451,000 — a 15 percent reduction since 2012.

Nationwide, it's estimated that about half of wetlands have been drained. In California the figure is far more pronounced: Nearly 95 percent of wetlands are gone. Wetland areas are important to waterfowl not only for sustenance but also as molting and breeding grounds.

Waterfowl seeking out new viable areas often converge in larger groups. This creates short-term benefits for their predators and can lead to massive damage to the waterfowl population, since diseases like avian botulism and cholera can spread easily.

"Avian cholera is spread by secretions from birds," said Holly Heyser, editor of California Waterfowl magazine. "In wetlands the bacteria tend to concentrate on the surface, so takeoff, landing and other disturbances can aerosolize it. When you have intense crowding, then, you have a lot more activity that aerosolizes the bacteria."

If the drought conditions persist, the already shrunken community of waterfowl could diminish further as diseases ravage the waterfowl population, reducing them by the thousands.

California's deer population, which numbered over 2 million in the 1960s, has dropped to less than half a million in recent years, primarily because of habitat loss and predation, with hunting also playing a minor role. If the state's drought continues, drying streams and ponds could be a cause for more concern, especially as vegetation dwindles.

Mule deer typically forage for woody vegetation such as shrubs and leaves, eating grass to a lesser degree. Found all over California, they prefer hill terrain and keep close to sources of water. As the drought stretches on, water levels drop and vegetation shrivels, deer are converging on remaining water holes, facing similar perils as the waterfowl.

"Such activity during a severe drought can concentrate these animals and help spread parasites and disease," said Holley. "It can also attract predators, such as mountain lions."

As deer search for water, it could bring them — along with their natural predators, mountain lions — into closer contact with humans.

More than half of California is mountain lion habitat, with the animals numbering 4,000 to 5,000. Though territorial, mountain lions will follow food and water, even if that means being closer to civilization. Most likely, though, mountain lions will take advantage of concentrated populations of mule deer around ever scarcer watering holes.

"Lions and other predators may enjoy increased opportunities if the drought weakens prey populations," said Holley, who added that it would benefit them only in the short term, because ravaging prey populations could leaving predators without enough food in the long run.

The black bear population in California is estimated at 25,000 to 30,000. Most the black bears' diet is vegetation such as shoots, buds, fruits and nuts. They also consume insects like bees and ants. Though California sees active bears every winter, especially along the coast, people could find bears increasingly rummaging through their refuse and belongings if drought conditions don't improve as the bears expand their search for food because of dying vegetation.

"It's everyone's responsibility to help keep animals wild by removing attractants, and if the drought persists, it will be even more vital to do so," said Holley.

Poor snowpack — currently at only 12 percent of normal levels — and record low precipitation mean that reservoirs and rivers in California are leaving fish high and dry, particularly the salmon population.

The salmon industry provides tens of thousands of jobs to Californians and generates over $1 billion in economic activity per year. Though the state has already barred fishing for most salmon, with a few designated hatcheries excepted, low water levels could threaten a die-off if rain doesn't come soon.

Even those designated hatcheries may be at risk without more rain. As rivers that feed them dry up, some salmon get stranded in areas not conducive to spawning.

Without more precipitation, the endangered coho salmon faces potential extinction; already its migratory routes leading to the Pacific Ocean are clogged with sand. The coho, explained water program director Brian Stranko from the Nature Conservancy, has a strict three-year cycle — unlike most other salmon, which swim out to sea and return two to four years later.

"In some places, we're concerned that we're going to lose an entire year of salmon," he said. "It's very disturbing, and it's happening on multiple parts of the coast. Populations of multiple river systems could be on the brink of extinction."

Though the outlook seems bleak, some much-needed precipitation could still save many coho runs — if it comes soon. "We still have time to get some rain," said Stranko. "Either we get some rain or we may be looking at extinction."

Though all wildlife will experience problems related to a continuing or worsening drought, the hardest hit may be species that are already endangered or threatened, particularly amphibians like the tiger salamander and rodents like the giant kangaroo rat.

The giant kangaroo rat lives only in California's Central Valley. More than 95 percent of its original habitat has been destroyed. 

"The giant kangaroo rat is a prey species for the (endangered) San Joaquin kit fox, so you'll see a real ripple effect that could be real problematic," said Stranko.

He also pointed out the dire situation of the tiger salamander, a species dangerously low in numbers and now having to contend with drying habitats. "If the ponds and wetlands that they use dry up, they're at risk of local extinction. You could have populations disappear," said Stranko.

"The problem with threatened and endangered species is that they are also experiencing several other stressors, at generally lower population numbers," said Holley. "Therefore, threatened and endangered species will be less able to rebound from severe drought effects as easily as normal wildlife populations may."