Cactus Wrens Need Cacti


charlene_W2_picThroughout history, advancements in technology and acquisition of knowledge have led to the expansion of human territory. People, whether they realize it or not, are invading the homes of not only animals but plants as well. There is only so much that these species can take until they themselves begin to decline in numbers along with their acreage of habitat. Colleen Wisinski, Senior Research Technician for the Applied Animal Ecology and Applied Plant Ecology Divisions at the San Diego Institute for Conservation Research, taught us about the devastating effects of human intrusion on local plants and animals.

Ms. Wisinski explained to us the rarity of certain ecosystems, specifically the coastal sage scrub ecosystem. Unfortunately due to the flat and coastal characteristics of this Mediterranean ecosystem, it makes it ideal for urbanization. It does not stop there however, coupled with urbanization is the introduction of non-native species to the environment, which leads to increased competition and interference between the invasive and indigenous species. The Coastal cactus wren (campylorhynchus brunneicapillus) for instance, is the subspecies of the cactus wrens found right here in San Diego. It has become a species of special concern due to habitat loss and urbanization. Recovering the cactus wren population has proven to be difficult, as Ms. Wisinski explained. Cactus wrens rely heavily on cacti for shelter as well as food. Making the restoration of cacti especially urgent.

However, it has been difficult to restore the number of cacti for the Coastal cactus wren. The wrens prefer to build their nests in cactus stands that are at least three feet tall, which takes approximately five years to grow. Devastating wildfires impacted much of this critically endangered habitat back in 2007 and many cactus wrens lost their homes. Unlike other bird species, cactus wrens are dispersal- limited, meaning that they do not move very far from their current habitat, making it harder to recover their population. In an effort to restore the wrens’ habitat, Ms. Wisinski, along with other conservationists, has experimented with the planting of cactus pads, planting them upright, flat, and horizontally at the biodiversity preserve located adjacent to the San Diego Zoo Safari Park. They also experimented with amount of water the cacti received. The most effective strategy that they discovered in growing the cacti seemed to be caging them. It protected the cacti from animals that nibble and nip at them, allowing the cacti to grow at a faster rate.

As an Ecologist, Ms. Wisinski has also had the responsibility of monitoring the number of Cactus coastal wrens in the area. She has surveyed the population of cactus wrens on the biodiversity preserve, placed bands on the nestlings to keep track of them, and set up camera traps in order to observe breeding behaviors. The efforts of restoring the wrens are laborious. The ecological research that is required to provide answers to the problems facing the wrens can take years.

We, as humans, must be considerate of other organisms that inhabit the planet. Our homes take homes, our intrusion destroys, and our existence imposes. Learning to live with other animals as well as learning to take care of the environment alone will have a great impact on how species survive. Awareness is key. If people are more knowledgeable about endangered species and environmental threats, then that initiates the driving force for action. Simply by getting involved in restoring a species’ habitat, for instance, could make all the difference.

Charlene, Conservation Team
Week Two, Winter Session 2013