Drought affects wildlife on first day of spring

The sunny, warm weather may be a pleasure for humans, but it is showing signs of negatively impacting local wildlife, a Midpeninsula Open Space District biologist said.

The current drought, which is one of the most severe in California history, has left breeding ponds for amphibians dry and could upset the life cycles of animals from frogs to deer, Cindy Roessler said.

Rain from recent storms only began to fill a pond on district land in the Santa Cruz Mountains in Palo Alto, and although she observed newts and frogs clamoring to lay eggs, many native animals may not come out of their burrows, missing a year of reproduction, she said.

“Some amphibians won’t be able to reproduce. They need several months of water. There won’t be a pond to reproduce in if there is no more rain,” she said.

The effects are more than hypothetical. Newts that came out of their burrows after the second big rain emerged in late February, three months later than normal.

“For weeks they looked really skinny. You could see the vertebrae on their backs sticking up,” Roessler said.

Last week, while out checking ponds in the area, Roessler was pleased to see fat newts in reproduction mode. But amphibian eggs, including those of frogs that currently line the pond, must hatch into tadpoles. They are at risk of dying if the ponds dry up too soon, she said.

Some mammals also seem affected, she said. The black-tailed deer have unusually thin coats. The deer change their coats twice a year, from reddish in summer to bluish in fall and winter.

“In spring the change starts at one end of the body to the other end. But they look bare — even the yearlings. There’s not much on their hips,” Roessler said.

Roessler said she doesn’t know what is causing the change in the deer, but speculated it could be the warm temperatures or nutritional deficiencies. Perennial plants deer depend on might not be growing fast enough to produce adequate forage, she said. That could result in fewer births this spring.

“The biggest factor for fawns is the diet of does in winter, If they are not getting enough nutrition, more fawns will not survive to birth. But the true impact won’t be known until birthing season in April and May, she said.

The drought could have a silver lining when it comes to invasive species, she said. Native plants and animals are adapted to California’s drought cycles, but some other species that have taken over native niches are not. The drought could hurt reproduction in nonnative American bullfrogs, a voracious predator that can consume endangered and threatened small-animal species.

“Their tadpoles need two years to develop. If the drought continues, it could interfere with two reproductive years,” she said.

Invasive annual plant species, such as grasses, are being knocked back by the drought, which has been a boon to native grasses. The sprouting seeds of European grasses that usually cover many California hillsides — they are the ones that turn hillsides tawny in summer — dry up when there is scant soil moisture, and the survivors tend to produce less seed. Native perennial grasses have a better chance without the competition, she said.

“Last year the perennials took advantage,” she said, noting that bigger-seeded plants such as lupine and soap plant proliferated.

This spring could become a pretty good year for wildflowers due to the reduced competition. But there is a delicate balance between getting enough rain at the right time to allow the native flowers to grow. In drought, there may be flowers, but they could be stunted. But Roessler was hopeful.

“We’re starting to see high coverage of annual lupines. It’s a little early to tell. It’s all about competition out there,” she said.

The normal cycles are being altered due to the drought, however, she said. Grasses are making seeds earlier, and some migratory birds, such as swifts, are arriving earlier. And the newts are going through parts of their reproductive cycle much more rapidly than in the past.

“Last week I was out checking ponds. There were lots of fat newts. At night, after the second big rainstorm, we were seeing hundreds chasing down bugs and earthworms. But they went through that part of their cycle really fast. They are getting back to their summer homes sooner than usual,” she said.