@Monyer Al-Fatlawi Can you please give me exact article sir?

I can't understand your point.

The  Nitrogen content in faecal matter is a function of trophic position of an animal. Naturally N content increases as you step up from herbivores to predators. Along with feeding habit and food type, the type of bird, body size and weight also determine the total nitrogen content although the C:N ratio of fecal matter is phylogenetically fixed. 

@ Jayanta Biswas

Thank you sir. I was also thinning so

Can you give me any reference for it?

Dear Sagar,

the paper below has been accepted for publication in Ecology and should be available soon. According to the abstract: " The dataset includes 10,534 observations from freshwater and marine animals of N and/or P excretion rates. These observations represent 491 species, including most aquatic phyla." Sounds interesting.

Kind regards,

Michał Filipiak

http://onlinelibrary.wiley.com/doi/10.1002/ecy.1792/full

Article A global database of nitrogen and phosphorus excretion rates...

 Thank you very much Michal Filipiak sir. I will obviously go through this article.