Population survival inside a dynamic forest

breed [forest one-forest] ; forest patches
breed [birds bird]        ; living birds

globals [ total-patches   ; Measure the total number of patches
          cumul-birds-list   ; List to calculate the average of bird proportion
          gr-forest
          gr-birds
        ]

to setup-ini
  clear-all
  set total-patches count patches
  set-default-shape birds "circle"
  set-default-shape forest "circle"
  set cumul-birds-list []
end 

to setup
  setup-ini

  ask n-of initial-population patches [
    sprout-forest 1 [set color green set size 1]
    sprout-birds 1 [ set color white set size .7]
  ]
  reset-ticks
end 

to setup-full
  setup-ini
  ask patches[
      sprout-forest 1 [set color green set size 1]
      sprout-birds 1 [ set color white set size .7]
  ]
  reset-ticks
end 

to setup-center
  setup-ini
  ask patches with [(abs pycor < 6) and (abs pxcor < 6)]
  [
    sprout-forest 1 [set color green set size 1]
    sprout-birds 1 [ set color white set size .7]
  ]
  reset-ticks
end 

to go
  ;; updates the probabilities of growth
  set gr-forest birth-rate-forest /( death-rate-forest + birth-rate-forest )
  set gr-birds birth-rate-birds /( death-rate-birds + birth-rate-birds )

  ask forest [ grow-forest ]
  (ifelse
    birds-behavior = "NoSelection" [
      ask birds [ grow-birds-no-selection ]
    ]
    birds-behavior = "BirthSelection" [
      ask birds [ grow-birds ]
    ]
    birds-behavior = "AdultSelection" [
      ask birds [ grow-birds-adult-selection ]
    ]

  )
  ;calc-birds-mean

  tick
  if habitat-proportion = 0 [stop]
  if (check-birds-extinction = true) and (birds-proportion = 0) [stop]
end 

to grow-forest
  ifelse random-float 1 > gr-forest
  [
    ;show "1 forest died"
    die
  ]
  [
    ask one-of neighbors4 [
      if not any? forest-here [
         sprout-forest 1 [set color green set size 1]

      ]
    ]
  ]
end 

;;
;; birds procedure: if newborns select a suitable patch if exist
;;

to grow-birds
  ifelse random-float 1 > gr-birds
    [ die ]
    [
      if any? forest-here [

          let target one-of neighbors4 with [any? forest-here  and not any? birds-here]
          if target != nobody [
            hatch-birds 1 [ move-to target ]
          ]
      ]
    ]
end 

;;
;; Birds procedure: birds select at random a patch to newborns
;;

to grow-birds-no-selection
  ifelse random-float 1 > gr-birds
    [ die ]
    [
      if any? forest-here [

        let target one-of neighbors4
        if (any? forest-on target and not any? birds-on target) [
          hatch-birds 1 [ move-to target ]
        ]

      ]
    ]
end 

;;
;; Birds select a suitable patch for newborns and if the forest dies they select a new forest patch
;;

to grow-birds-adult-selection
  ifelse random-float 1 > gr-birds
    [ die ]
    [
      ifelse any? forest-here [

        let target one-of neighbors4 with [any? forest-here  and not any? birds-here]
        if target != nobody [
          hatch-birds 1 [ move-to target ]
        ]
      ]
      [
        ;;show (word "Se va a mover" pxcor pycor)
        let target one-of neighbors4 with [any? forest-here and not any? birds-here]
          if target != nobody [
            move-to target
            ;; show (word "se movio!!!!!!!!"  pxcor pycor)
          ]
      ]
    ]
end 

to-report habitat-proportion
  report count forest / total-patches
end 

to-report birds-proportion
  ;print "Calculate birds proportion"
  report count birds / total-patches
end 

to calc-birds-mean
  ;if empty? cumul-birds-list
  ;; drop the first member of the list, but not until there are at least 100 items in the list
  if (length cumul-birds-list > 200) [ set cumul-birds-list but-first cumul-birds-list ]

  ;; add the number of birds-proportion in last tick to the end of the list
  set cumul-birds-list lput birds-proportion cumul-birds-list
end 

to-report check-birds-steady-state
  if ticks > 500 [

    let up-birds mean cumul-birds-list + (  standard-deviation cumul-birds-list )
    let down-birds mean cumul-birds-list - ( standard-deviation cumul-birds-list )

    if birds-proportion > down-birds and birds-proportion < up-birds
    [ report true ]
  ]
  report false
end