The first known Cassin’s auklet chick of the year hatched at Southeast Farallon Island last week, and it looks like this:
These seabirds create burrows underground to nest in. This prevents predators like Western gulls on the Farallon Islands from easily preying on the young. The burrows are excavated by the birds themselves, with both parents using the sharp claws on their webbed feet to excavate the soil. On the Farallones, they also make good use of the man made nest boxes which allows biologists to monitor their breeding success.
The female Cassin’s auklet lays a single white egg. It hatches after about 40 days, and out pops a fuzzy black ball. The parents leave the burrow and come back at night to feed the chick by regurgitating food they picked up in the ocean. 40 to 50 days after hatching, the young Cassin’s auklet fledges (flies out of the nest) and into the ocean where it is able to swim and dive right away.
As adults, both the female and male Cassin’s auklet are small and stocky, with round heads and short necks. They are dark gray in color with lighter bellies, and have blue feet. Their bills are short and thick with a pale white spot at the base of the lower mandible. The white crescents above their eyes make them look like they have angry eyebrows.
They feed by “flying” through the water. Cassin’s auklets use their wings to propel themselves to depths of 120 feet below the ocean’s surface where they feed on shrimp, amphipods, copepods and some small fish and squid.
In 2014, thousands of Cassin’s auklet carcasses were found along the coasts of the western United States. Necropsies revealed little food in their stomachs, leading scientists to believe starvation was the main cause of death. This might have been related to the warm ocean waters at the time which could have reduced their food supply.
On many islands, non-native rodents cause havoc on the local wildlife by killing animals that have not evolved a defense against them. But on the Farallon Islands, the effect of the introduced mice is not as direct.
Every fall burrowing owls stop by the Farallones during their fall migration where they find a plentiful food source in house mice that were brought to the island by humans. Seal hunters, commercial egg collectors, lighthouse keepers and the U.S. Navy and Coast Guard have all occupied the island in the past hundred plus years.
A recent sample estimated there could be up to 1300 mice per hectare during certain times of the year. It is among the highest mouse densities reported in science. This large amount of available food keeps the burrowing owls on the island long after they would normally depart for their winter ranges. In fact, there was still at least one burrowing owl on the island in the middle of April.
But every winter, the mouse population crashes during its annual cycle. The burrowing owls then turn to hunting rare ashy storm-petrels, which begin arriving in late winter in preparation for the spring breeding season.
Ashy storm-petrels only breed on islands and rocks off the coast of California and northern Baja California, including Southeast Farallon Island. It is estimated that there are only about 8000 of these birds breeding each year, half of which are on the Farallones. The U.S. Fish & Wildlife Service has identified the ashy storm-petrel as a Species of Management Concern and the California Department of Fish and Wildlife have listed them as a Bird Species of Special Concern. The ashy storm-petrel is also listed as Endangered by the International Union for the Conservation of Nature.
The US Fish and Wildlife Service and Point Blue Conservation Science are developing a plan to eradicate the mice from Southeast Farallon Island. It is their hope that eliminating the mice will prevent burrowing owls from overstaying into the winter and feeding on ashy storm-petrels. Additionally, removing mice would also help other species such as the Farallon arboreal salamander, invertebrates and plants that would benefit from less predation and consumption.
But El Niño looks to be ending and cooler ocean waters have been recorded lately around the Farallones. The gulls are also pooping pink from the krill they are eating, which is a good sign for the food web. Maybe the mothers who are still healthy and pregnant will be able to have better success weaning their pups later this summer.
A lot of people think that the ocean should have clear blue waters like the ones on tropical vacation photos. That’s not the case for California’s seabirds. They prefer the ocean to have a murkier green color as it signals a phytoplankton bloom that boosts the food web and provides more fish for them to eat.
From NOAA’s Green Seas Blue Seas website: “Through oceanographic surveys of the region’s chemical, physical and biological make up, scientists discovered a steady, long-lasting cycle of natural climate variability that alternates between warmer and cooler temperature regimes, often called the Pacific Decadal Oscillation. During the cooler regimes, increased phytoplankton productivity caused by nutrient-rich upwelling at the ocean’s surface causes the waters of the California Current to take on a greener hue. Warmer, less productive waters tend to have a deeper blue color.”
This does not mean blue waters are “bad.” It just means that some wildlife like green waters more than blue ones. In fact, a different set of marine animals thrives in blue sea conditions. Seabirds such as murrelets and albtrosses, northern anchovies, and salmon prefer colder green seas while Pacific mackarel, yellowfin tuna, sunfish and moon fish prefer warmer blue ones.
Although Southeast Farallon Island is almost 50 kilometers off the west coast of San Francisco, California, USA, sometimes it feels like it is hundreds of kilometers away from civilization. The towering skyscrapers are just dots on the horizon – and that’s on a rare clear day. Instead of a bustling metropolis of people, this chunk of granite that juts sharply out of the ocean is crammed with hundreds of thousands of seabirds and an abundance of seals and sea lions. A cacophony of shrieks, grunts and other calls resonate throughout the island around the clock. High winds blow from the northwest, causing waves to break heavily on jagged rocks. It’s one of the wildest places imaginable, and it’s just in San Francisco’s back yard.
Every day since the 1960’s, biologists from Point Blue Conservation Science (formerly Point Reyes Bird Observatory), in cooperation with the U.S. Fish and Wildlife Service, have lived on the island, studying its wildlife. This has given the organization something rarely seen in ecology: long term data sets of a variety of species. This has allowed them to document the changes in population numbers and species composition as ocean conditions change over the years, answering many questions about how environmental changes affect wildlife.
The Farallones are home to the largest seabird breeding colony in the USA outside of Alaska and Hawaii. A quarter of California’s breeding seabirds, 300,000 birds of 13 species, are arriving on the island now.
This is what large woody debris installation for estuary restoration looks like. It was just a straight channel of water just a few weeks ago – not much more than a large ditch. No, it is not exactly “natural conditions” as it is probably only a fraction of the wood that was originally there and the logs are cabled in place. But this does restore some structure and function to the estuary that has been missing for the past 100+ years. At high tide, when the woody debris is submerged, it will provide refuge habitat for fish and additional habitat complexity. A secondary side channel was also added.
Special thanks must go out to the crews led by the BCIT Rivers Institute that worked 2 weeks of long nights at Lynn Creek estuary in North Vancouver to bring back a little bit of nature to the city.
Phytoplankton is the foundation of the ocean food web. But it needs two things to grow: sunlight and nutrients. Sunlight is plentiful on the ocean surface where plankton float. Nutrients, not so much. Instead, they are at the bottom of the ocean where decaying organic matter sinks down to.
This is where upwelling kicks in. When strong winds blow across the surface of the ocean, it pushes water away. This water is then replaced by deeper water from beneath, bringing nutrients with it. These nutrients act as fertilizer for phytoplankton, increasing their growth, and subsequently the fish and other marine feeding activity across the food web.
One of the greatest places to experience upwelling is the California coast near San Francisco. Here, upwelling produces nutrient rich waters that provide a smorgasbord of good marine eating.
Just a couple of hundred of years ago, the estuaries around Metro Vancouver were filled with fallen trees and other large woody debris that had drifted down from upstream headwaters. Large woody debris gave young salmon adapting to salt water conditions cover from their predators and helped in the establishment of healthy intertidal vegetation. It also added structural complexity to the fish habitat: creating riffles, pools and crannies with different water conditions. Without this, their habitat becomes very uniform – just a straight flowing stream. Think of a neighborhood filled with only one bedroom apartments or a food court that only sold pizza. It doesn’t give young fish a lot of options.
But when humans started to develop these waterfront habitats for industrial and residential uses, we removed all this wood. It just got in our way. The estuaries were transformed into not much more than large ditches, seriously degrading fish habitat.
Now, humans are looking to restore these habitats by bringing back the wood. Large woody debris structures (kind of like small log jams) are installed into the estuary stream bed by securing them to boulders using cable and epoxy cements. Echo Ecological describes the process on their website. No, not exactly natural, but large logs can’t be allowed to drift around waterways that are used heavily for commercial shipping and recreational boating.
It could take a few years to see improvement, but with more work like this, we just might see more young salmon heading out to the open ocean from Vancouver’s estuaries and, even better, returning in larger numbers to spawn new generations.