Isla Santa Esteban
For many naturalists the most interesting aspect of any region is the unique interactions that take place between species. While exploring the desert environment of Isla San Esteban this morning, we had the opportunity to witness many of these fascinating relationships. The cardón cactus occur throughout Baja California and are often pollinated by bats, but today several different animals could be seen serving as pollinators including bees, hummingbirds and tarantula hawks (a large wasp). This type of ecological relationship is referred to as mutualism and both species benefit from the presence of the other. One of the hiking groups witnessed a small violet-green swallow nesting in a cavity of a large cardón which is a significant benefit to the bird, but does little harm to the plant. This is also a common relationship and is referred to as commensalism.
This image to the right we can see a very direct relationship between a beautiful spiny-tailed iguana and the large white flowers of the cardón cactus as the iguana feeds on the flowers. This large lizard is endemic to San Esteban and one other island on the Sea of Cortés and feeds on a variety of plant material but appears to prefer the flowers of the cardón. Each of these relationships offers testimony to the importance of the cardón cactus within the Baja ecosystem.
A final relationship seen today is much more disconcerting. Two individual rats were seen on the island today which are almost certainly an introduced species and had not been documented until today. This sighting is significant (and unfortunate) since the native species of San Esteban have evolved without such land predators and these rats pose a great threat to nesting birds and other small animals.
For many naturalists the most interesting aspect of any region is the unique interactions that take place between species. While exploring the desert environment of Isla San Esteban this morning, we had the opportunity to witness many of these fascinating relationships. The cardón cactus occur throughout Baja California and are often pollinated by bats, but today several different animals could be seen serving as pollinators including bees, hummingbirds and tarantula hawks (a large wasp). This type of ecological relationship is referred to as mutualism and both species benefit from the presence of the other. One of the hiking groups witnessed a small violet-green swallow nesting in a cavity of a large cardón which is a significant benefit to the bird, but does little harm to the plant. This is also a common relationship and is referred to as commensalism.
This image to the right we can see a very direct relationship between a beautiful spiny-tailed iguana and the large white flowers of the cardón cactus as the iguana feeds on the flowers. This large lizard is endemic to San Esteban and one other island on the Sea of Cortés and feeds on a variety of plant material but appears to prefer the flowers of the cardón. Each of these relationships offers testimony to the importance of the cardón cactus within the Baja ecosystem.
A final relationship seen today is much more disconcerting. Two individual rats were seen on the island today which are almost certainly an introduced species and had not been documented until today. This sighting is significant (and unfortunate) since the native species of San Esteban have evolved without such land predators and these rats pose a great threat to nesting birds and other small animals.
