although certain preferred embodiments of the present invention will be shown and described in detail , it should be understood that various changes and modifications may be made without departing from the scope of the appended claims . the scope of the present invention will in no way be limited to the number of constituting components , the materials thereof , the shapes thereof , the relative arrangement thereof , etc ., and are disclosed simply as an example of the preferred embodiment . the features and advantages of the present invention are illustrated in detail in the accompanying drawings , wherein like reference numerals refer to like elements throughout the drawings . referring to fig1 there is illustrated a perspective view of the bird feeder 10 in accordance with the present invention . the bird feeder 10 includes a housing 12 , a support shaft 14 , a support element 16 , a support element 18 , and a feed tray 20 . the housing 12 is free to rotate greater than 360 degrees about the support shaft 14 . the feed tray 20 is rigidly attached to the support shaft 14 . the bird feeder 10 is attached to an external support system 51 . the external support system 51 can preferably include an essentially horizontal branch 50 . the support elements 16 and 18 are attached to the branch 50 of a tree 110 by a flexible connector 52 and a flexible connector 54 . the flexible connectors 52 and 54 are preferably formed of rope , however , it should be appreciated that many other materials such as wire or twine can be used . the housing 12 includes a side wall 22 , a side wall 24 , a top plate 26 and a bottom plate 27 . the side walls 22 and 24 are preferably formed from a transparent material such as plastic or glass to allow a person to see through the side walls 22 and 24 and observe a bird ( not shown ) inside the housing 12 . the top plate 26 and the bottom plate 27 are attached to the side walls 22 and 24 by suitable means such as by screws , glue , or the like . the top plate 26 and the bottom plate 27 are formed from a hard smooth surfaced material such as aluminum or plastic to prevent an animal 40 from gripping the surface with its claws . as illustrated in fig3 the bottom plate 27 includes a counterweight 56 so that after spinning , the housing 12 will always return to the same at rest orientation with the counterweight 56 located at the bottom of the bird feeder 10 . the counterweight 56 is rigidly attached to a lower portion of the bottom plate 27 . as illustrated in fig1 and 2 , the side walls 22 and 24 included in the housing 12 are rotatably attached to the support shaft 14 by a bearing assembly 100 and a bearing assembly 102 . the bearing assemblies 100 and 102 allow rotation of the housing 12 about the support shaft 14 while preventing movement of the housing 12 in an axial direction along the axis of the support shaft 14 . the top plate 26 includes a circular surface 32 , a protruding portion 28 , and a protruding portion 30 . the protruding portions 28 and 30 extend upward at an angle from the circular surface 32 ( fig3 ). the bottom plate 27 includes a circular surface 34 , a protruding portion 36 , and a protruding portion 38 . as illustrated in fig3 the protruding portions 36 and 38 extend downward at an angle from the circular surface 34 . the protruding portions 28 , 30 , 36 , and 38 cause the housing 12 to rotate when an animal 40 such as a squirrel contacts one of the protruding portions 28 , 30 , 36 , or 38 . the protruding portions 28 , 30 , 36 , and 38 are preferably flat , however , many other shapes such as curved , concave or convex shapes can be used . in the preferred embodiment of the present invention , a cylindrical portion 29 of the housing 12 is formed by the circular surface 32 of the top plate 26 in combination with the side walls 22 and 24 and the circular surface 34 of the bottom plate 27 . preferably in the present invention , the cylindrical portion 29 of the housing 12 is about 12 inches in diameter , and the protruding portions 28 , 30 , 36 , and 38 extend about 4 inches from the cylindrical portion 29 . as illustrated in fig1 and 3 , the housing 12 has an opening 60 and an opening 62 . the opening 60 is formed by the upwardly protruding portion 28 , the side walls 22 and 24 , and the downwardly protruding portion 38 . the opening 62 is formed by the upwardly protruding portion 30 , the side walls 22 and 24 , and the downwardly protruding portion 36 . preferably the openings 60 and 62 are about 8 inches high and about 14 inches wide . a bird ( not shown ) can fly through either opening 60 and 62 and can land directly on the feed tray 20 . the feed tray 20 includes a plurality of side walls 70 , 72 , 74 and 76 and a base 78 . the combination of the side walls 70 , 72 , 74 , 76 , and the base 78 , form a region 80 for containing bird feed 81 ( fig1 ). in addition , the feed tray 20 includes a flat upper surface 82 that provides a perch on which a bird can land and stand on for feeding . the flat upper surface 82 is formed by the upper surfaces of the side walls 70 , 72 , 74 , 76 , and extends around the entire upper periphery of the feed tray 20 . to exit the bird feeder 10 , the bird flies directly from the feed tray 20 and out through one of the openings 60 or 62 . in addition , the feed tray 20 includes a lower counterweight 84 to help maintain the feed tray 20 in an upright position when strong winds blow against the feed tray 20 . thus , bird feed 81 is prevented from spilling because the feed tray 20 always remains in an upright position . the lower counterweight 84 is attached to the base 78 by the support elements 86 and 88 ( fig1 , and 3 ). as illustrated in fig1 and 2 , the feed tray 20 is rigidly attached to the support shaft 14 by a bracket 90 and a bracket 92 . thus , the lower counterweight 84 maintains the feed tray 20 in a upright position , while the counterweight 56 attached to the bottom plate 27 returns the rotatable housing 12 to a horizontal orientation . filling the feed tray 20 with feed such as bird seed is accomplished by rotating the housing 12 until the opening 60 or the opening 62 is in an upward location . next , bird feed 81 can be easily poured into the feed tray 20 . the transparent side walls 22 and 24 enable a person to easily see how much feed is in the feed tray 20 . as illustrated in fig1 through 4 , the bird feeder 10 can be mounted from the branch 50 of a tree 110 . preferably the branch 50 is essentially horizontal in orientation . a first end 110 of the support element 16 is rigidly attached to the support shaft 14 and a second end 112 of the support element 16 is formed into a loop 114 . a first end 116 of the support element 18 is rigidly attached to the support shaft 14 and a second end 118 of the support element 18 is formed into a loop 120 . a flexible connector 52 connects the loop 114 of the support element 16 with the branch 50 of the tree 110 . a flexible connector 54 connects the loop 120 of the support element 18 with the branch 50 of the tree 110 . the flexible connectors 52 and 54 are spaced at a distance &# 34 ; w &# 34 ; of greater than about 18 inches ( fig2 ). this distance &# 34 ; w &# 34 ; prevents the rotating housing 12 from contacting the flexible connectors 52 and 54 . the flexible connectors 52 and 54 are preferably made from rope , however , it should be appreciated that many other materials can be used . for example the flexible connectors 52 and 54 can comprise wire or twine . the flexible connectors 52 and 54 are attached by crimping , twisting , or by tying knots . fig2 illustrates an end view of the bird feeder 10 . preferably the bird feeder 10 is mounted at least a distance &# 34 ; d &# 34 ; of about 4 feet away from the nearest vertical element such as a tree trunk 130 . this distance &# 34 ; d &# 34 ; prevents the animal 40 from leaping directly from the tree trunk 130 to the feed tray 20 without touching and causing a rotation of the rotatable housing 12 . in addition , the bird feeder 10 is preferably mounted from a horizontal member such as a branch 50 that is at least a height &# 34 ; h &# 34 ; of about six feet above a ground surface 132 . this distance &# 34 ; h &# 34 ; above the ground surface 132 ensures that the animal 40 will not leap from the ground surface 132 into the bird feeder 10 . the support shaft 14 is preferably mounted at least about 25 inches from the branch 50 . this distance from the branch 50 allows the housing 12 to rotate freely beyond 360 degrees . the distance &# 34 ; a &# 34 ; between the support shaft 14 and the opening 60 in the housing 12 is at least about 9 inches ( fig3 ). this distance &# 34 ; a &# 34 ; prevents animals such as a squirrel 40 from being able to crawl from the support element 16 , to the support shaft 14 , and into the opening 60 of the housing 12 . in a similar manner , the distance of at least about 9 inches between the support shaft 14 and the opening 62 , likewise prevents the animal 40 from entering the opening 62 . fig5 is an end view of another embodiment of a feed tray 150 with a support cable 152 , and a support cable 154 . the feed tray 150 includes a plurality of side walls 156 , 158 , 160 , 162 , and a base 164 . the combination of the side walls 156 , 158 , 160 , 162 , and the base 164 , form a region 168 that contains bird feed 81 . in addition , the feed tray 20 includes a flat upper surface 170 that provides a perch on which the bird can land and stand on for feeding . side walls 156 and 160 include projecting elements 172 and 174 that receive and rigidly attach the support shaft 14 to the feed tray 150 . in addition , side walls 156 and 160 include projecting elements 180 and 182 to receive and rigidly attach the lower counterweight 84 to the feed tray 150 . the counterweight 84 helps maintain the feed tray 150 in an upright position when strong winds attempt to tip the feed tray 150 . thus , bird feed 81 is prevented from spilling because the feed tray 150 remains in an upright position . the side walls 22 and 24 of the housing 12 are rotatably attached to the support shaft 14 by the bearing assemblies 100 and 102 . a first end of the support cable 152 is rigidly attached to the support shaft 14 by a clamp 188 . a second end of the support cable 152 is formed into a loop 192 by rigidly attaching the cable 152 back onto itself by tightening a clamp 194 . in a similar manner , a first end of the support cable 154 is rigidly attached to the support shaft 14 by a clamp 196 . a second end of the support cable 154 is formed into a loop 198 by rigidly attaching the cable 154 back onto itself by tightening a clamp 200 . the flexible connectors 52 and 54 can be used to connect the loops 192 and 198 to the branch 50 . the distance &# 34 ; l &# 34 ; of the support cables 152 and 154 is at least about 25 inches as illustrated in fig5 . this distance &# 34 ; l &# 34 ; allows the housing 12 to rotate freely beyond 360 degrees . in the preferred embodiment of the present invention , the sides 22 and 24 of the housing 12 are transparent allowing people to clearly see a bird flying into the bird feeder 10 , feeding , and flying out of the bird feeder 10 ( fig1 ). also , it can be very entertaining for a person to watch an animal such as a squirrel 40 trying to reach the bird feed 81 . often a squirrel 40 will climb the trunk 130 of the tree 110 , run out on the branch 50 supporting the bird feeder 10 , climb down the flexible connector 52 or 54 and support element 16 or 18 toward the bird feeder 10 , and jump onto the rotatable housing 12 . as illustrated in fig3 as soon as the squirrel 40 contacts any one of the protruding portions 28 , 30 , 36 , or 38 , the housing 12 will rotate . in addition , the protruding portions 28 , 30 , 36 , and 38 are made from a hard surfaced slippery material , so that the squirrel 40 is not able to grip the protruding portions 28 , 30 , 36 , and 38 with its claws . as illustrated in fig4 the spinning housing 12 causes the squirrel 40 to fall to the ground surface 132 . thus , the squirrel 40 never reaches the bird feed 81 in the feed tray 20 . a squirrel 40 will often climb the trunk 130 of the tree 110 and will repeat the process over and over providing entertainment for the person watching . in the present invention , the housing 12 is free to rotate at least 360 degrees . when the housing 12 stops spinning , the counterweight 56 attached to the bottom plate 27 causes the housing 12 to always return to the same at rest orientation . the foregoing description of the present invention has been presented for purposes of illustration and description . it is not intended to be exhaustive or to limit the invention to the precise form disclosed , and many modifications and variations are possible in light of the above teaching . for example , the support elements 16 and 18 may be directly attached to the external support system 51 . the housing 12 may have at least one opening 60 , and the feed tray 20 may be in a shape other than rectangular . for example , the feed tray 20 may be circular or square in shape . the entire housing 12 may be made from a transparent material , and the housing 12 may be made from suitable materials such as injection molded plastic , steel , aluminum , wood , etc . such modifications and variations that may be apparent to a person skilled in the art are intended to be included within the scope of this invention as defined by the accompanying claims .
a bird feeder that prevents animals such as squirrels , chipmunks , and rodents from gaining access to feed in the bird feeder . the bird feeder protects the feed from wind , rain , and snow . the bird feeder includes a housing that is rotatably attached to a support shaft allowing at least 360 degrees of rotation . the housing includes a plurality of angled plates that cause the housing to spin when the animal contacts one of the plates . a feed tray is rigidly attached to the support shaft and remains upright and stationary within the housing while the housing rotates about the support shaft . a bird can fly through an opening directly to the feed tray . transparent sides of the housing allows a person to watch the bird .