Alright im certain youre not aware, but Summoning Technique is a Space-time ninjutsu and one of the definite laws of Space-time is that the chakra consumption is directly proportional to the mass of of the object summoned/teleported. Since there are ranks even among summons, the amount of chakra taxed is an indicator of the animal summoned since we've seen often that the summoner doesn't realize the animal he has summoned until it appears, the most latest example is when naruto summoned gamakichi. Summoning Bosses like Bunta or Manda requires massive chakra reserves so keep in mind that summoning technique can be exhausting. Try summoning a tadpole first...I take the scroll from my sensei and write my name in Kanji on it. But before that, I nick my thumb so there si a small but steady stream of blood that I must use to sign the contract. I start writing on the scroll with my thumb, signing:
" シャンクス " or " Shanks "