Wednesday, September 24, 2008

Understanding and using trade-off behaviors to help migrating birds

To determine stopover sites based on trade-offs between foraging opportunities and predation risks, the authors used Western Sandpipers (Calidris mauri) as their research species. These birds migrate between Peru and northern Oregon with stopovers at Georgia Basin (British Columbia, Canada) and Pugent Sound (Washington, USA). It is thought the birds use visual clues to determine quality foraging sites. The invertebrates the birds eat live in mud- and sand-flat environments that are easily spotted while flying. The birds follow the same route year after year and can change their stopovers depending on energy reserves and quality of site. Raptors are the main predator for this species. The raptors use tree and brush cover to surprise the unsuspecting migrants. Better quality sites would be those that are large open areas with minimal cover and abundant foraging opportunities. Poorer quality sites are those that are small open areas with lots of tree and brush cover providing hiding spots for raptors. Thinner birds have to endure poorer quality sites because they can not fly as far or compete for prime feeding areas with birds that are in better shape. By using feeding vs predation behaviors as factors in determining stopover sites the authors were able to predict which sites the birds would most likely choose on their migration to and from their breeding grounds in Oregon.

I thought this was interesting because scientists are using two key behaviors exhibited by these birds to determine which sites would be more worthwhile protecting as habitat encroachment and global warming take-their-toll. No one has enough money to save all sites so we are down to protecting the most profitable ones. By understanding behaviors we are able to provide the most beneficial assistance to this species.

Posted by Allan Eldridge (2)


At 9:41 AM, Anonymous Anonymous said...

This is a great way of protecting the species with the little bit of assistance that is out there. I have never heard of looking at the species' trade-offs in order to figure out which of the habitats would be best suitable for the species, and which ones do not "need" protecting. Even though all the areas should be protected, it is not possible in this day and age, so this is a very realistic and valuable tool. What do you think will happen if the poorer sites were not protected and ended up being turned into another kind of landscape? Do you think the weaker birds who have been using that landscape for foraging would be likely to adapt to the new terrain, since they are not able to make it to the prime habitat? Or do you feel that this would eventually result in he die-off of the weaker populations. And how do you think that would relate to the population as a whole?

Posted by: Katie Cole

At 5:20 PM, Blogger PWH said...

I found this to be a very interesting post from a personal experience perspective. I live in an area of wetlands, and there happens to be a rather well-sized swamp in the woods just behind my house. Up until about 3-4 years ago migrating ducks would use the swamp as a stopover on their migratory path. However, in recent years there as been an rather noticeably decline in the conditions of the swamp. Its water level rarely ever gets above a few inches anymore and the effects can be seen the general vegetation surrounding it. Since its conditions have deteriorated the ducks have not returned. This article gave me a wider sense of how habitats coincide with certain animal's behavior. Thanks for posting.

-Benjamin Spozio

At 3:51 PM, Anonymous Anonymous said...

I learned in intro ecology class that birds have different niches, thus different species live in different time periods of a day, and different places even in one tree; for example, owls (at night) vs. hawks (day time) or smaller birds in lower portion of a tree vs. larger birds in higher portion of the tree. It will be interesting to mention how weaker birds sometimes forage in the same place as stronger birds.

-Yi, Jeongsang

At 9:56 PM, Anonymous Anonymous said...

I think its great that scientists are really focusing on the areas that really need help. I was wondering what were the methods they used to determine their decisions? Do they tag or band any of the birds and record their migratory patterns? What are the specific sites that the researchers are focusing their time and energy on? Is it only the species listed in your post? Is research focused primary in Oregon? Do they give any statistics about their predictions versus their observed sites? Thank you for enlightening us.

Posted by: Amanda Sceusa

At 11:46 PM, Blogger PWH said...

Great article! It is survival of the fittest and an interesting fact that the larger more fit birds take over the better foraging locations and force the less fit smaller birds into poor foraging sites which makes these birds more vulnerable to predation. I would like to know more about what scientist are doing to conserve these special habitats and what methods they use to maintain these ecosystems.

Carlos A. Varela

At 11:17 PM, Anonymous Anonymous said...

this really makes me think of how mush global warming can affect not only our survival but that of almost everything living. very interesting -matthew sousa

At 6:37 PM, Anonymous Anonymous said...


Thanks for the comments. The weaker birds have to choose the poorer sites, this means greater chances of getting eaten themselves. For shore birds like these, there are only so many stopover sites along the entire route. The government sets aside a certain amount of wetlands every year and various organizations like the Nature Conservancy protect millions of acres of critical habitat annually. Research like this shows concerned groups where to invest their money and time.

posted by Allan Eldridge


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