During the Gulf Oil Spill off the Louisiana coastline, hundreds of birds were saved using these protocols. See the trailer and our blog post on the West Coast film opening. Found a Bird? How Oil Affects Birds.
Oil can be lethally harmful to seabirds — particularly to diving birds that spend a great deal of time on the surface of the water where the oil sits. Oiled wings can kill birds. Pelican from Gulf Oil Spill in Before and after cleaning Bird feathers are naturally waterproof, but to maintain this, each feather must be aligned properly so that water cannot seep through the microscopic barbs and barbules that are part of the vane of each feather.
Nonetheless, the researchers' field team—"quite intrepid field assistants," says Dr. Taylor—wake up early to comb the marshes for these nests in the heat of the summer when the sparrows are breeding.
Once they find a nest, they check to see whether the eggs have hatched and, if they have, how old the chicks are. The project isn't yet complete, but the researchers have published some preliminary results.
In and , several years after the spill, sparrows that built their nests on previously oiled marsh had far less luck in raising their young. In , about half of the parents who laid their nests in unoiled marshes successfully reared their nestlings to fledging, when they leave the nest—but only 5 percent of those laid in oiled marshes did the same.
There are several explanations for why chicks aren't surviving in previously oiled marshgrass. One is that the toxins from oil remain in the environment and are harming the young. Nestlings could eat oil-related toxins if the insects and other critters that their parents dig up from the mud are contaminated.
Another possibility is that there is less or different food in the oiled marsh areas because the insect community shifted after the spill.
The researchers are collaborating on projects to examine that question as well, including looking at adult sparrow diets and observing the food items being brought to the nests for the chicks. Another question the researchers have is whether the remaining oil is affecting the adult sparrows.
The main danger of the most toxic parts of oil, called PAHs for polycyclic aromatic hydrocarbons, is that they can cause cancer and liver disease, suppress the immune system and reproduction, or have developmental effects. For example, the precious energy used to process and eliminate the PAHs could leave them without enough to feed themselves or raise their young.
The researchers are looking for the activation of a gene called CYP1A, which begins the process of metabolizing PAHs, in adult seaside sparrows in order to know if they are still encountering fresh oil and toxic PAHs.
They are also looking at stress hormones in the birds' blood to see if detoxifying from the oil stresses them out, which could also affect their reproduction. Dr Perez continued: "We expected that the birds would have difficulties with flight and be slower in their arrival, but we did not expect such an obvious flight path difference. The study used crude oil collected from the Deepwater Horizon oil spill which was applied onto the wing and tail feathers of some of the homing pigeons with paintbrushes.
This pattern of oiling reflected that seen in wild birds from the spill. The pigeons were trained to repeatedly undertake flights of km between release points and their home loft, all the while carrying GPS data loggers.
After release, most of the oiled birds took different flight courses which were longer in duration and distance than those of un-oiled birds. These longer flights, more than double the length of the un-oiled birds, avoided crossing lakes and made use of the updrafts from mountains. They chose to minimise the risk of overwater crossings and may have been using their knowledge of the environment to make the journey easier.
Such options would be unavailable for migrant water birds that had become oiled on their first migration. Young birds, with their pre-programmed flight plans would have no idea of the environmental barriers, such as long overwater flights, that they would meet on their onward migration.
Historically, the focus has been on understanding the impact on heavily oiled seabirds, but study co-author and project leader Prof Chris Pritsos stressed the importance of such work to understand the impact on lightly-oiled birds, which he pointed out "were observed oiled but still alive and functioning" after the Deep Water Horizon spill.
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