for this song you only need these four chords:
-F 
-C 
-E 
-Am

The strumming pattrern changes throughout so just have a listen to the song and 
see what works for you :)

(accapella)
Well I didn't tell anyone but a bird flew by
saw what i'd done he set up a nest outside
and he sang about what i'd become

   F (133211@1)           CHe (x32010@1)sang so loud, sang so clear
E (022100@1)                  AmI (x02210@1)was afraid all the neighbours would hear
     F (133211@1)                    Cso (x32010@1)i invited him in just to reason with him
  E (022100@1)                 Ami (x02210@1)promised I wouldn't do it again

            FBut (133211@1)he sang louder and louder inside the house
    Cand (x32010@1)now i couldn't get him out
     Eso (022100@1)I trapped him under a cardboard box
    Amand (x02210@1)stood on him to make it stop
  FI (133211@1)picked up the bird and above the din i said
C(stop short)
that's the last song you'll ever sing
Fheld (133211@1)him down broke his neck
Ctaught (x32010@1)him a lesson he wouldnt forget

  E (022100@1)name="chord_x02210@1">Am
    
    F (133211@1)            CBut (x32010@1)in my dreams began to creep
     E (022100@1)          Amthat (x02210@1)old familiar tweet, tweet, tweet

  E (022100@1)    
I opened my mouth to scream and shout
  AmI (x02210@1)waved my arms and I flapped about 
      Ebut (022100@1)I couldn't scream and I couldn't shout
Amcouldn't (x02210@1)scream and couldn't shout
  FI (133211@1)opened my mouth to scream and shout
  AmI (x02210@1)waved my arms and I flapped about 
      Ebut (022100@1)I couldn't scream and I couldn't shout
    Am (x02210@1)                    F (133211@1)     Cthe (x32010@1)song was coming from my mouth
        E (022100@1) Amfrom (x02210@1)my mouth
        F (133211@1) C*from (x32010@1)my mouth
        E (022100@1) Amfrom (x02210@1)my mouth*

*Repeat 4 more times with same chords-you can put variations if you wish, like 
plucking instead of straight chords

(Am--->)F   C
from my mouth
        E (022100@1) Amfrom (x02210@1)my mouth
        F (133211@1) Cfrom (x32010@1)my mouth
        E (022100@1)      F (133211@1)    C (x32010@1)    E (022100@1)    Am (x02210@1)    F (133211@1)   C (x32010@1)   E (022100@1)    Amfrom (x02210@1)my mouth (held on)-------------------------------------------->

F to finish

hope you like it :)