Abstract:
A bird feeder, including a method for deterring animals, is comprised of two sections, an upper section attached to a support structure, and a lower section attached to the upper section through a spring loaded member, where the weight of a bird causes little deflection of the spring, but the weight of a rodent such as a squirrel will cause the spring to deform, moving the lower piece in relation to the upper piece, thereby activating a mechanism to distress the squirrel, causing it to leave.

Description:
FIELD OF THE INVENTION 
     The present invention relates to bird feeders in general. More specifically, it relates to a bird feeder that provides a signal to scare off any pests that may be attempting to feed. 
     BACKGROUND OF THE INVENTION 
     Bird feeders are known in the art. Typically a bird feeder consists of a hollow tube that is filled with bird feed. The type of feed varies with the type of bird the user would like to attract. There are feed holes in the side of the tube through which the bird may access the feed. There are also perch points such as pegs placed adjacent to the feed holes so that the bird may stand on the perch point while feeding. 
     This is an effective design to attract birds to the feeder so that the user may enjoy the sight of the birds. However, other animals also are attracted to the easily-acquired food such as squirrels. Squirrels, being large in comparison to most birds, eat great amounts of the feed and scare away the birds. Thus, the user is deprived of the enjoyment of watching the birds eat. It is advantageous, then, to have an apparatus which allows birds to access the food but keeps squirrels and other undesirable animals away. 
     Several designs have been proposed. It is known to put a constant voltage across various locations on the bird feeder, at such a distance that only a large animal, such as a squirrel, would be able to close the circuit, thereby sustaining a mild shock. However, this has the disadvantage of producing a constant voltage potential, and the inherent danger that it presents. Also, a desirable large bird might close the circuit and receive a shock, thereby being driven away. It is also known to use a weight-activated mechanism, taking advantage of the greater weight of the squirrel compared to a typical bird, to block access to the food itself when the squirrel alights on the feeder, or to activate a motor which gyrates the feeder until the squirrel is thrown off. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 illustrates a bird feeder constructed in accordance with an embodiment of the present invention. 
     FIG. 2 illustrates a bird feeder constructed in accordance with another embodiment of the present invention. 
     FIG. 3 illustrates a bird feeder constructed in accordance with a third embodiment of the present invention. 
     FIG. 4 illustrates a bird feeder constructed in accordance with a fourth embodiment of the present invention. 
     FIG. 5 illustrates the fourth embodiment of the invention in use. 
    
    
     DETAILED DESCRIPTION 
     Referring now to the drawings, bird feeder  10  is shown in an assembled condition. The feeder  10  is constructed of an upper section  11  and a lower section  12 . The upper section  11  can include a hollow portion, and can be used to house the bird feed  19 . It is also possible that the lower section  12  can be used to house the bird feed  19  (not shown). The upper section  11  can be of any cross sectional configuration, including circular, square, octagonal, etc. In the example shown in FIG. 1, the upper section  11  has a circular cross section. The upper section  11  has a bottom portion  20 . Feed access holes  13  adjoin the upper section  11 . These holes in the side of the upper section  11  are constructed large enough such that a bird will easily be able to access the feed inside. 
     The feeder  10  may be fastened to a support structure (not shown) using an adjustable ring or clasp  18 . The support structure may be a tree branch or a post, for example. The clasp  18  may be connected to an umbrella  9 . The umbrella  9  is releaseably attached to the upper section  11 . This can be accomplished by threading complementary sections of the umbrella  9  and the upper section  11 . The umbrella  9  serves as a cap to seal the interior of the upper section  11 . The umbrella  9  can further be made large enough, with a sloping angle, and out of a slippery substance such that a squirrel will not be able to hang upside down and feed simultaneously. 
     The lower section  12  also has a hollow portion. It, too, can be of any cross sectional shape. In the present embodiment, the upper section  11  and lower section  12  are sized such that the upper section  11  can easily slide up and down inside the lower section  12 . Adjoining the lower section  12  is a feed tray  17 . The bird stands upon the tray  17  while feeding. Although the tray  17  is shown as a plate, it should be clear to one skilled in the art that any surface upon which a bird may alight is also useful. The tray  17  may also be moved up or down relative to the lower piece  12  and the feed holes  13  to account for a particular size or species of bird. 
     In an example not shown in the drawings, the lower section  12  can be configured to contain feed  19  and include feed holes. 
     The upper section  11  and the lower section  12  are capable of relative motion to each other via, for example a spring loaded member  14 . In the present example, a coil spring is disclosed. The stiffness of the spring  14  is selected such that a bird, when alighting on the tray  17 , causes very little expansion of the spring. However, when a squirrel or similar rodent alights on the tray  17 , the spring  14  expands under the greater weight. 
     Attached to the bottom portion  20  of the upper section  11  is a signal generating device  15 . Attached to the inside of the lower section  12  is a signal activation member  16 . In FIG. 1, the signal activation member  16  is shown as a bar extending into and through the upper section  11  through slots  21 . Signal generating device  15  can be battery powered, and if applicable, may automatically rewind. It can be any device known in the art such as a micro cassette tape player, a digital recorder, a programmable MP3 player, or any other device capable of emitting a signal. 
     It should be noted that although it is shown that the signal generating device  15  is attached to the upper section  11 , and the signal activation member  16  is attached to the lower section  12 , the converse would also function as well. Specifically, the signal generating device  15  can be attached to the lower section  12 , and the signal activation member  16  can be attached to the upper section  11 . 
     When the squirrel comes to rest on the tray  17 , its greater weight causes the spring  14  to expand. The lower section  12  descends and brings the signal activation member  16  into contact with the signal generating device  15 . This causes the signal generating device  15  to activate and it emits a sound that is distressing or frightening to the squirrel. After the squirrel departs, the spring  14  contracts and returns the lower section  12  to its original position. The signal activation member  16  ceases to be in contact with the signal generating device  15 , and the distressing signal stops. 
     FIG. 2 shows another example of the present invention. In this example, upper section  23  is shown larger in diameter than lower section  24 . Again, upper section  23  and lower section  24  may be of any cross sectional shape, such as circular, square, octagonal, etc. Bird feed  19  is contained within the upper section  23 . Feed holes  22   a  and  22   b  exist in the upper section  23  for the bird to access the bird feed  19 . The spring mechanism  29  shown is a common pillow spring, although any similar structure could be used. The lower section  24  also includes a feed plate  27 . The feed plate  27  serves as a perch point for the birds, as well as a mounting location for an ultrasonic source  25 . Ultrasonic sources, known in the art to be another form of a signal generating device, repel rodents and/or insects, but do not affect birds or other household pets such as a dog. An example is PestContol PC 01 G from Lentek® which could easily be adapted for use in the present invention by those skilled in the art. The upper section  23  includes a peg  26 , and the feed plate  27  includes a complementary aperture  28  through which the peg travels. While the peg  26  maintains contact with the ultrasonic source  25 , the ultrasonic source  25  remains inactive. 
     A bird, with its relatively minimal weight, will not cause the spring  29  to expand. However, when a squirrel lands on the feed plate  27 , its weight causes the spring  29  to expand. Peg  26  is then released from the ultrasonic source  25 , causing it to emit a distressing signal, affecting only rodents and insects. In a further example, a peg may contact the ultrasonic source  25  to cause it to emit a distressing signal. When the squirrel departs, the spring returns the lower piece  24  to its original position, and peg  26  is returned to the ultrasonic source  25 , causing it to cease operating. 
     A further embodiment is shown in FIG.  3 . Here, an electrical device such as a battery  31  is fastened to the underside of an upper section  36 . The positive and negative terminals  34   a  and  34   b  are releasably connected to inlaid exposed wire on the feed plate  37 . There is a positively charged wire  32  and a negatively charged wire  33 . Again, when a bird alights on the feeder, no relative motion occurs between the upper section  36  and a lower section  38 ; the battery remains unconnected to the inlaid, exposed wires  32  and  33 . 
     Once the squirrel settles on the feed plate  37 , however, the springs  35   a ,  35   b , and  35   c  expand, and the battery terminals  34   a  and  34   b  are connected to the wires  32  and  33 . Although the wires  32  and  33  remain an open circuit, the squirrel standing on the feed plate  37  will likely complete the circuit with its body, thereby sustaining a mild shock. It is also possible to have one terminal permanently connected to minimize possibility of the connections missing, as shown in FIG.  3 . Although only one set of exposed wires is shown, it may be desirable to add more sets of exposed wires in parallel, thereby increasing the chances that the squirrel will close the circuit. 
     FIG. 4 discloses a fourth embodiment of the bird feeder  49 . An upper section  40  is connected to a lower section  41  via a coil spring  43 . Feed holes  47  are disposed in the upper section  40 . A signal generating device  44  is mounted on the bottom of the upper section  40 . Attached to the signal generating device  44  is an activation lever  45 . 
     Disposed on the bottom section  41  is an activation slot  46 . When the squirrel or other pest alights on the tray  42 , the coil spring expands under the weight, and the activation slot  46  descends until it is brought into contact with the activation lever  45 . The slot  46  then biases the lever  46 , activating the signal generating device  44 . Again, the signal generating device emits a sound that is frightening or distressing to a squirrel. 
     FIG. 5 depicts the bird feeder  49  being used in nature, with the clamp  48  fastening the feeder to a pole  50 . 
     The foregoing detailed description has been given for clearness of understanding only, and no unnecessary limitations should be understood therefrom, as modifications will be obvious to those skilled in the art.