For the mathematical minded:

x=number of days since you been in the studio
y=number of days it’s rained since you’ve been in the studio
z=number of shredded tissues found in the lower floor
b=whether it’s sunny outside or not (yes=(-20), no=(+5))
c=whether you left food in studio (yes=(+20), no=(-5))
a=the likeliness of an animal awaiting you in the studio (percentage)

a=xy(z+1)+b+c

Today I came into shed…

It’s been 1w1d since studio visit.
     Therefore, let x=8.
It has rained 4 times.
     Therefore, let y=4.
There is one tissue down stairs.
     Therefore, let z=1.
It is sunny outside.
     Therefore, let b=(-20).
I left no food in the studio.
     Therefore, let c=(-5).
The likeliness of animal visit is:

a=8*4*(1+1)+(-20)+(-5)
a=8*4*2-20-5
a=39%

As the percentage indicates, there is no animal in the studio today.