By Josh Pike
In the fall, the Riverwalk Wetlands can appear barren and drab. Patches of still water, surrounded by dead brown stalks, sprawl across the wetland expanse while the leaves fall from the nearby trees. However, if you look carefully, the wetlands in the fall are replete with activity and interesting sights. This article gives a sensory tour of the changing wetlands, highlighting the ecology underlying the sights and smells.
Walking through the wetlands, the first thing that may strike you is the rich scent of decaying leaves that fills the air. The many trees and shrubs in the wetlands, from willows to chokecherries to cottonwood, all drop their leaves in the fall. By doing this, the trees free themselves from defending their vulnerable water-filled leaves from the winter chill, and enter a state of hibernation through the short days of winter.
Scanning the pond edges, you will notice the cattails and reeds turning brown. These plants also let their stalks and leaves die back, relieving the plant from having to protect them from the cold. However, unlike the leaves, which end up in loose piles on the ground, these stalks remain upright and rigid throughout the winter, creating extensive banks of dead vegetation where the living plants used to be.
Traversing the Riverwalk path through the wetlands, you might feel the biting winds that accompany the change of seasons. The wetland wildlife feel those same winds and the dead reed banks provide one of their primary defenses against them. In the curves of banks or inside the reeds, winter birds and mammals can find shelter from the wind chill and from the falling snow.
Across the wetlands are narrow trails cut through the vegetation, and trenches carved through the sediment. Many of these are left by muskrats, one of the most sophisticated users of the dead reeds. Besides eating reeds and cattails, the muskrats also use this plant material to build large wintertime shelters called push-ups. These shelters are up to three foot tall structures built of dead vegetation and mud. Muskrats spend much of the winter within these push-ups, leaving only to feed, and keeping the entrance closed at all other times.
While there may be ample shelter for birds and animals in the wetlands, the question still remains: what can these animals eat? The answer begins with the steam that rises off the wetland ponds in the crisp fall mornings. Because the wetlands are fed by hot geothermal water, their temperature does not dramatically drop during the winter and the water never freezes over completely like most other ponds in the area.
If you walk to the edge of one of the wetland ponds and look into the water, you will see the results of the wetland’s unique water source. Beneath the water, a wide variety of plants and invertebrates flourish, even once the surrounding vegetation has died off. These organisms provide a primary source of nutrition for the animals that spend the winter in the wetlands, helping sustain a variety of birds and mammals that swim, dabble or dive in these waters to harvest the food growing on the bottom.
Swimming on the wetland ponds are ducks, from green-winged teal to American widgeon, the most visible of the wetland’s fall and winter residents. These birds utilize the open water and the vegetation growing underneath to feed them during their winter stay in the wetlands. During this time, they will also form crucial mating pairs and social groups for their migrations northward in the coming spring.
The other main source of food in fall wetlands can be found in the bare branches and the dead stalks of vegetation that started our journey through the wetlands. For songbirds and rodents alike, the berries and seeds remaining on these stalks are the provisions that will sustain them through the cold months. The rich vegetation provides a particularly large amount of food, in addition to shelter. For this reason, many animals choose to make their winter homes in and near the wetlands.
A close look will reward you with many interesting sights during an autumn walk through the Riverwalk Wetlands. The key is to look beyond the drab exterior and find what is moving and changing in the wetlands. Even in their seemingly quiet and dead state, the Riverwalk Wetlands are constantly shifting, growing and living.
If you want to learn more about the Riverwalk Wetlands or get involved in protecting them, please contact Pagosa Wetland Partners at pagosawetlands@gmail.com.
Josh Pike writes on behalf of Pagosa Wetland Partners.