We are looking at guano deposition rates by tropical seabirds to anticipate the benefit of a seabird roosting habitat improvement project at Palmyra Atoll. Data on Booby guano deposition rates would be a huge help.
Hi, my supervisor used to study this species some years ago at Paracel Islands (xisha islands) in China. They estimated the dropping rate by long-time observation of what do whey eat, when do they excrete, and so on. If you focus on the short-period deposition rate, maybe you can try this. If you focus on the long-period deposition rate, maybe you can follow the methods described for penguins in the Antarctic, which is led by another professor in our school, Prof. Liguang Sun from University of Science and Technology of China. They collected soil cores from Antarctic, and analysed the deposition rate of penguin droppings using diverse methods, such as stable isotopes. Hope this be useful.
Hi Alexander, not sure if you have an answer for this yet?
To calculate seabird nitrogen excretion rates you can use the method of Wilson et al. (2004). Nitrogen excreted (Fe, g N bird-1day-1) can be calculated from the adult mass (M, g bird-1), nitrogen content of the food (FNc, g N g-1wet mass), energy content of the food (FEc, kJ g-1wet mass) and assimilation efficiency of ingested food (Aeff, kJ [energy obtained] kJ-1[energy in food]).
Fe = (9.2 x FNc x M^0.774)/(FEc x Aeff)
Typical values:
FNc= 0.036 g N g-1 (Furness, 1991; Wilson et al., 2004)
FEc, = 6.5 kJ g-1(Furness, 1991; Wilson et al., 2004; Blackall et al., 2007).
AEff= 0.8 (Furness, 1991; Wilson et al., 2004; Blackall et al., 2007).
Hope this helps,
Stuart
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