Measurements were taken of the local mean sea surface temperature (SST) of Johnston Atoll in order to find the effects of SST variation on pre-breeders choice to postpone breeding for a season or if it caused breeders to become skippers. They also measured survival rates for the different life stages that were studied and how at what age pre-breeders first begin to breed.
The data used to form models included measurements of the transition probabilities from Pre-Breeders to Breeders, from Breeders to Skippers, and finally from Skippers to Breeders again.
Their multi-state models found that El-Nino's climatic changes in SST did in fact impact Red-Footed Booby's and overall increased the skipping behavior of less fit Booby's for a years breeding season. It was also observed that first time breeders would actually begin breeding with the presence of increases SST levels. This meant that the breeding season's environment does not weigh on the cost of reproduction for the Red-Footed Booby's as much as competitive interactions do between they and their colonies experienced breeders.
Posted by "Shyla Morsbach"(5).
http://rsbl.royalsocietypublishing.org/content/early/2010/10/13/rsbl.2010.0778.full.pdf+html
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ReplyDeleteIt is interesting to think that because of the increased sea surface temperature (SST) that the "less fit" Booby's skip breeding, while the first-timers would increase. Because there is less competition for breeding, it would be an opportunity that first-timers would take. But how successful are these first-timers? Probably only the fittest are able to be successful, but what about those who failed then? Was it "wise" for the "less-fit" ones to skip a breeding season because the cost of that year would outweigh the benefit? There seems to be a relationship where the less-fit Booby's would increase the benefit or lower the cost of breeding season for the first-timers by skipping a season. So then how does the "less-fit" Booby's determine to skip? What do they do when they do skip?
ReplyDeletePosted by Leona Chan
They also studied the survival rates for the different life stages. Do you know how the offspring are affected based on whether they were conceived during higher or lower sea surface temperatures?
ReplyDeletePosted by Katie Kalutkiewicz
I am surprised any of the birds, especially males, would ever choose to skip a season. Is there some special danger, or cost to these brids if they fail in a season that would make it beneficial not to try at all? To try and fail, in most cases, is rarely all that detrimental. What makes it so costly to these birds, here?
ReplyDelete-Alice Trei
How successful are these first-timers? Probably only the fittest are able to be successful, but what about those who failed then?
ReplyDeleteThe article states that the annual survival of pre-breeders is “between 60 and 100 per cent and adult survival was 90 per cent” (2). However, it gives no numerical rate of first-timers reproductive success. I would assume that if 60-100% is surviving including young and adult pre-breeders, then the success rate for their first breeding is high. For those who do not succeed in their first breeding, the cost of their survival may be in limbo. If a year of high SST occurs post breeding season, they might die from expending too much energy in breeding in place of energy for foraging. In another case, if there is ample food available, the bird may not suffer at all but have had no offspring to increase the population. I think their survival success depends greatly on the SST and how much energy they are spending to carry out foraging and reproducing.
Was it "wise" for the "less-fit" ones to skip a breeding season because the cost of that year would outweigh the benefit?
I believe skipping is a wise adaptive behavior the “less-fit” Booby’s partake in because they’re physically at a disadvantage. El-Niño causes a need to spend an excess amount of time foraging for food because “an increase in the SST is generally associated with changes in productivity at lower trophic levels” (1). If sea waters are warmer, many natural foods will not be available. They will not have ample energy from their natural food sources to compete with other males, perform mating rituals, and, if a female, to produce offspring. It is like our conversation in class about not having enough fruit in the environment so the birds have to change their strategies to survive and produce. By waiting for food supplies to increase again with cooler SST’s, these Booby’s can gain enough energy to carry out reproduction the following year, rather than possibly dying from over-expenditure of its body’s energy during high SST.
How does the "less-fit" Booby's determine to skip? What do they do when they do skip?
I believe they skip when the energy needed for foraging is excessive and when competition with experienced breeders is high. They must be “able to process predictive information about the quality of the breeding season, they should be aware of a high probability of reproductive failure in some years and preserve their own survival by delaying first breeding or skipping reproduction for breeders” (1). The article states “they generally do not attend breeding” when they skip so I assume they attempt to find better feeding grounds (1).
Do you know how the offspring are affected based on whether they were conceived during higher or lower sea surface temperatures? The article does not state what affects the SST has on the offspring but says that there are studies that “reported low
numbers of breeding pairs and/or nest counts related with El-Niño events in tropical and Antarctic species” (3).
Is there some special danger, or cost to these birds if they fail in a season that would make it beneficial not to try at all? To try and fail, in most cases, is rarely all that detrimental. What makes it so costly to these birds, here?
I think in this article the cost has more to do with extreme environmental conditions for these “less-fit” birds. If they are already expending a large amount of energy to find a scarce amount of food, due to the warmer waters from El-Niño, then the cost of reproductive behaviors and copulation itself might be too taxing on a less-fit animal (especially if it were all for an unsuccessful breeding).
Posted by Shyla Morsbach