Patent Publication Number: US-7219621-B2

Title: Anti-squirrel bird feeder

Description:
PRIOR HISTORY 
   This application is a continuation-in-part patent application claiming priority to pending U.S. patent application Ser. No. 10/840,963, filed in the U.S. Patent and Trademark Office on May 7, 2004 now U.S. Pat. No. 6,918,353. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention generally relates to a bird feeder apparatus. More particularly, the present invention relates to a bird feeder apparatus designed to provide a readily available source of feed to birds, while further functioning to prevent other small animals, such as squirrels and raccoons, from gaining access to the bird feed. 
   2. Description of the Prior Art 
   The study of birds is formally referred to as ornithology and within the broad compass of ornithologists is found a remarkable array of bird enthusiasts. They range from the person who notices which bird species visit the garden birdbath to the computer buff trying to mathematically describe the fate of some host population subject to the parasitic attentions of cowbirds or cuckoos. To be sure, bird enthusiasts are well-numbered and these numbers continue to grow. Accordingly, markets continue to develop in an effort to cater to the growing needs and desires of the bird enthusiast population. In this last regard, it is noted that there are two avenues by which the typical bird lover or ornithologist pursues his or her study of birds. Either the bird enthusiast will travel to the ecosystem in which the various bird species live or the bird enthusiast will attempt to lure or attract various bird species to the “ecosystem” in which the bird enthusiast lives. It is with this latter trend in mind that the present invention is proposed. In other words, a growing desire among bird enthusiasts or bird watchers is to attract various species of birds to the vicinity of the residential abode or similar other setting in which the watcher spends a considerable amount of time. 
   The most successful way of attracting birds and increasing their number in a given setting is to satisfy their most basic needs—good food, nesting sites and water. In this regard, the bird feeder is useful in any attempt to attract birds to a given setting. Providing a source of food, however, has a tendency to attract not only birds, but other wildlife, such as squirrels and raccoons. Given the uncanny ability for squirrels and the like to deplete stores of bird food from bird feeders, a number of attempts have been made to develop an effective anti-squirrel or squirrel proof bird feeder. Thus, anti-squirrel bird feeders are known in the prior art, some of which are described hereinafter. 
   U.S. Pat. No. 5,163,382 (&#39;382 Patent), which issued to Morrison, discloses a Bird Feeder Apparatus. The &#39;382 Patent teaches a bird feeder arranged to discourage squirrels from access to food within the feeder comprising a first housing reciprocatingly receiving an second housing, with the first housing including side wall openings and the second housing including side wall openings aligned in a first position and displaced in a second position when a squirrel alights upon a top wall of the first housing projecting the second housing within the first housing preventing access of the squirrel to food components within the second housing. 
   U.S. Pat. No. 5,195,459 (&#39;459 Patent), which issued to Ancketill, discloses a Bird Feeder. The &#39;459 Patent teaches a bird feeder comprising a food holder and shroud which is biased in an open position by a spring. When an animal such as a squirrel not intended to feed from the bird feeder lands on the shroud or a roof portion of the shroud, the weight of the animal causes the shroud to descend against the biasing action of the spring. The shroud closes the food holder thereby preventing the animal from gaining access to the food. 
   U.S. Pat. No. 5,720,238 (&#39;238 Patent), which issued to Drakos, discloses a Spring Operated Squirrel Proof Bird Feeder. The &#39;238 Patent teaches a squirrel proof bird feeder comprising an inner and outer housing with the inner housing fixed vertically and with the outer housing telescopically received thereabout and moveable between upper and lower positions. The housings have openings which are aligned and which provide through openings serving as feed ports in the upper position of the outer housing. In the lower position of the outer housing, the openings are misaligned and close the feed ports. The outer housing is also provided with springs biasing the same toward the upper position but allowing the housing to move downwardly to the lower position under the weight of the squirrel. 
   U.S. Pat. No. 5,964,183 (&#39;183 Patent), which issued to Czipri, discloses a Bird Feeder. The &#39;183 Patent teaches a bird feeder having an inner feed containing tube with a removable top, fixed bottom and feed access openings therein, an outer tube shrouding the inner tube and having feed access openings therein and an upper and lower position. In the upper position the feed access openings in the inner and outer tubes are aligned and when the outer tube moves downwardly relative to the outer tube the access openings are closed. A lever is pivotally connected to the fixed bottom and operatively connected to the outer tube. A biasing element urges the lever to pivot in a direction to move the outer member to its upper position. 
   U.S. Pat. No. 6,119,627 (&#39;627 Patent), which issued to Banyas et al., discloses a Rodent Repelling Bird Feeder. The &#39;627 Patent teaches a cylindrical rodent repelling bird feeder having an annular perch around the feeder and an electric motor geared to the perch. The perch is coupled to the electric motor and the electric motor is reciprocatively mounted in the bird feeder so that when a rodent of excessive weight alights upon the perch the motor is pulled against a resistance spring and a switch is caused to close, thereby engaging the motor which rotates the perch to dislodge the rodent therefrom. 
   U.S. Pat. No. 6,543,384 (&#39;384 Patent), which issued to Cote, discloses a Bird Feeder Having Lower Movable Shroud. The &#39;384 Patent teaches a squirrel proof bird feeder wherein there is provided a lower movable shroud which extends about a lower portion of the feed container having feed access openings therein, a spring member biasing the shroud to a position wherein feed container access openings and shroud access openings are substantially aligned while permitting the shroud access opening to move out of alignment with the feed container access opening when a predetermined weight is placed on the shroud. 
   From a review of these prior art disclosures and from a general consideration of other well known prior art teachings, it will be seen that most prior art anti-squirrel bird feeder designs incorporate either a linear closure mechanism based on a linear spring or a nonlinear closure mechanism based on a teeter-totter, mass balance. It will be seen that none of the prior art disclosures teach a non-linear, four-bar closure mechanism, which four-bar closure is of critical importance to the present invention and described in more detail hereinafter. 
   Generally, nonlinear closure mechanisms are preferable to linear closure mechanisms for anti-squirrel bird feeder applications. A linear mechanism closes linearly with load, i.e., closure is proportional to load; therefore, a linear closure mechanism is usually set heavy, i.e., set to reach full closure at a load equal to the weight of an adult squirrel, for example. The reason for a heavy setting is that a light setting can result in significant closure when only a few birds are feeding, restricting access to seed, thereby diminishing the utility of the feeder. The unsatisfactory consequence of a heavy setting, however, is that an immature or lightweight squirrel could defeat the closure mechanism. These properties of the linear mechanism are not present in nonlinear mechanisms making nonlinear mechanisms more desirable. 
   A nonlinear closure mechanism usually closes minimally until a critical point is reached when subsequently its closure occurs immediately and fully; therefore, it is far more desirable than a linear closure mechanism. The four-bar mechanism of the present invention is superior to a teeter-totter, mass balance type mechanism in that its action is less susceptible to adverse frictional effects that inhibit/prevent immediate and full closure; therefore, a four-bar mechanism is more robust as explained in the following paragraphs. 
   The four-bar mechanism&#39;s stability is based in geometry rather than mass balance. The unequilibrated moment about the pivot pin of a teeter-totter, mass balance mechanism is a function of the small difference between the squirrel&#39;s mass and the set mass; therefore a small amount of pivot pin friction could defeat the teeter-totter, mass balance mechanism by precluding closure. Noteworthy is that at least one teeter-totter design judged “undefeatable” has indeed been defeated by squirrels. Video taped documentation evidences two squirrels working in unison to defeat the teeter-totter type design. The reader should reference: “Daylight Robbery II”, which aired in the United States on the Discovery Channel on Nov. 26, 1995, having been produced by the British Broadcasting Corporation Worldwide Limited in 1995 as presented by Dr. Jessica Holm. One squirrel was observed to counterbalance the other preventing closure of the gate to the feeder&#39;s seed. Subsequently, one or the other of the two consumed the feeder&#39;s seed. Such cooperative action cannot defeat the four-bar mechanism of the present invention. The frictional moment about a pivot pin of the four-bar mechanism is acted upon by a function of structure&#39;s dead load plus its live load; therefore a four-bar mechanism can accommodate much larger pivot pin friction without significant adverse effects. Recovery of the four-bar mechanism is also more robust than the teeter-totter, mass balance mechanism because it is less affected by friction. Recovery at closure is based in geometry not mass balance, as the following specifications will clarify. Another advantage of the four-bar mechanism is that, unlike a teeter-totter, mass balance mechanism, the four-bar mechanism is not limited in feeder and closure design, which is usually bound to rectangular box-like structure. 
   SUMMARY OF THE INVENTION 
   It is thus an object of the present invention to provide a nonlinear, four-bar closure mechanism or a four-bar spring assembly for use in combination with an anti-squirrel bird feeder, which anti-squirrel bird feeder necessarily incorporates other inventive attributes in support of or in cooperation with the four-bar spring assembly. It is a further object of the present invention to provide a partitioned, removable (drop out-type) hopper, which allows for segregation of feed or seed types, easy cleaning and easy refilling even if the bird feeder is situated above a user&#39;s head. Further, it is an object of the present invention to provide feed gauge means or a status flag that indicates to the user whether the feed or seed hopper is full or empty. Still further, it is an object of the present invention to provide at least one surround perch assembly, as opposed to singular post-type perches, attached to a shroud assembly, which surround perch assembly allows uninhibited access to the circumjacent hopper tray. The surround perch assembly thus accommodates a multitude of small and medium sized birds and enhances viewing by bird watchers. 
   It is a further object of the present invention to provide a conical roof or shroud cap of such slope that it invites a squirrel to alight atop the shroud cap yet further functions to shed snow, water, and debris. Squirrels attempting to gain access to the feed tray of the present invention by positioning themselves atop the shroud cap will be thwarted in their attempts, since the squirrel&#39;s weight will cause immediate and full closure of the feeder. Still further, it is an object of the present invention to provide a coaxially corrugated bridge which serves not only as a flexible structural bridge to mitigate loading of critical parts whenever the shroud is subjected to an extreme load, but also as an internal umbrella for the feed hopper to preclude rain soaked seed or feed. A further object of the present invention is to provide a feed tray screen for reducing waste. The anti-flick grating or screen of the feed tray functions to thwart birds from flicking seeds out of the feed or hopper tray. Further, it is an object of the present invention to provide damage resistant construction resulting from the cooperative association of the coaxially corrugated bridge and self-aligning means. When conjoined in action, the corrugated bridge and the self-aligning means limit critical item stresses to within the elastic range when excessive lateral or vertical loads are applied to the perch assembly. 
   To achieve these and other readily apparent objectives, the present invention provides a bird feeder apparatus for providing a readily available supply of feed for birds. The bird feeder apparatus essentially comprises a telescopic-operational assemblage, a shroud assembly, and a hopper assembly. The telescopic-operational assemblage comprises a support assembly and a drive assembly. The support assembly essentially comprises a hopper scale assembly and hopper attachment means. The hopper scale assembly essentially comprises a support member (having support member length) and a scale spring. The scale spring is attached to the inferior end of the support member and the hopper attachment means is attached to the inferior end of the scale spring. 
   The drive assembly essentially comprises a four-bar spring assembly and a push rod shaft assembly. The four-bar spring assembly essentially comprises two superior bars, two inferior bars, first and second trunnion assemblies and a bar-joining junction assembly. The superior bars are pivotally connected to one another at the superior ends thereof by the first trunnion assembly and the inferior bars are pivotally connected to one another at the inferior ends thereof by the second trunnion assembly. The bar-joining junction assembly joins the inferior ends of the superior bars and the superior ends of the inferior bars. The junction assembly essentially comprises pivot attachment means pivotally connecting the superior bars to the inferior bars and spring means connecting the pivot attachment means. The pivot attachment means may thus have either a relaxed distance therebetween or a displaced distance therebetween, which relaxed distance and displaced distance are defined by the spring means when in either a relaxed or displaced state. The superior bars thus have a first angle therebetween at the superior pivot junction and the inferior bars have a second angle therebetween at the inferior pivot junction. The first and second angles are substantially equal to one another at any degree of displacement. The four-bar spring assembly thus provides a nonlinear, geometrically-based, closure mechanism driven by external load forces acting through the superior and inferior bars and countered by restorative forces in the spring means. 
   The superior and inferior trunnion assemblies each comprise a shaft-receiving aperture and shaft-fastening means. The push rod shaft assembly essentially comprises a superior shaft member, an inferior shaft member, an annular spring cup, and a recovery spring. The shaft-receiving apertures receive the superior and inferior shaft members, the superior shaft member being telescopically received in the inferior shaft member. The shaft-fastening means fasten the superior and inferior trunnion assemblies to the superior and inferior shaft members, respectively. The spring cup is affixed to the inferior shaft member adjacent the superior end thereof and the recovery spring is seated upon the spring cup intermediate the spring cup and the superior trunnion assembly for providing additional restorative spring force to the otherwise displaced four-bar assembly. 
   The shroud assembly essentially comprises a shroud bridge assembly and a shroud body. The shroud bridge assembly essentially comprises a corrugated shroud bridge, a trim weight, a collar, and collar fastening means. The shroud bridge is attached to the shroud body adjacent the superior end thereof. The superior end of the superior shaft member is received in the collar and the collar fastening means secure the superior shaft member to the shroud bridge. 
   The hopper assembly essentially comprises a substantially cylindrical hopper body, a substantially circular hopper tray, a plurality of vertical hopper partitions, and a shaft-receiving sleeve. The diameter of the hopper body is lesser in magnitude than the diameter of the shroud body for telescopic receipt therein. The inferior end of the hopper body comprises spacer-attachment means. The spacer-attachment means fixedly and concentrically attach the hopper tray to the inferior end of the hopper body in spaced relation thereto thereby defining feed outlet ports. The hopper partitions radially extend from the hopper body to the shaft-receiving sleeve for maintaining the shaft-receiving sleeve in concentric relation with the hopper body. The hopper partitions define a plurality of feed-receiving compartments, the feed-receiving compartments each having a substantially uniform feed-receiving volume. The hopper assembly is telescopically received in the shroud body, inferior portions of the push rod shaft assembly extending through the shaft-receiving sleeve. The support assembly extends through the push rod shaft assembly. As earlier noted, the scale spring is fixedly attached to the hopper attachment means, which hopper attachment means function to maintain the hopper assembly in telescopic relation to the shroud body. 
   The bird feeder further includes a perch assembly comprising a perch ring and ring attachment means. The perch ring has a ring diameter, which ring diameter is greater in magnitude than the diameter of the hopper try. The ring attachment means fixedly attach the perch ring to the shroud body adjacent the hopper tray for enabling birds of all sorts to perch and feed from the hopper tray. Further, the bird feeder may comprise feed gauge means or signaling flag assembly for indicating to a user the quantity of feed remaining in the hopper assembly. In this regard, the support member comprises pole-receiving structure. When the bird feeder is assembled, the pole-receiving structure is spatially located adjacent the superior end of the superior shaft member. The feed gauge means or flag assembly comprises a flag pole, a flag and pole attachment means. The flag pole comprises a flag end and a pole attachment end. The pole attachment means attach the pole attachment end to the pole-receiving structure and the flag is attached to the flag end for indicating to passersby the feed quantity in the hopper assembly. 
   The shroud assembly further includes a conical shroud cap comprising a superior cap surface, an inferior cap surface, a basal cone diameter, and a push rod-receiving aperture extending from the superior cap surface to the inferior cap surface. The basal cone diameter is greater in magnitude than the shroud body diameter and the superior shaft member extends through the push rod-receiving aperture. The superior end of the superior shaft member thus extends upwardly from the push rod-receiving aperture. The push rod-receiving aperture preferably comprises a spherical bearing for allowing the bird feeder to withstand unbalanced load forces directed against the shroud assembly. 
   The hopper tray comprises an anti-flick screen that extends radially from the inferior end of the hopper body for preventing birds from flicking seed from the hopper tray. The hopper tray further comprises debris outlet means, which means permit debris, but not seed, to fall out of the tray precluding clogging of the feed outlet ports in the hopper assembly. 
   A latch assembly comprising a latch body and a spring-loaded latch pawl may define the hopper attachment means of the support assembly. The latch pawl is compressible for releasing the hopper assembly from telescopic relation with the shroud body and extendable for maintaining the hopper assembly in telescopic relation with the shroud body. 
   Other objects of the present invention, as well as particular features, elements, and advantages thereof, will be elucidated or become apparent from, the following description and the accompanying drawing figures. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other features of my invention will become more evident from a consideration of the following brief description of my patent drawings, as follows: 
       FIG. 1  is a perspective view of the preferred embodiment of the anti-squirrel bird feeder with parts removed to show the drive mechanism assembly in a load-free, unactuated state with a feed-laden hopper assembly as indicated by a lowered flag. 
       FIG. 2  is a perspective view of the preferred embodiment of the anti-squirrel bird feeder with parts removed to show the drive mechanism assembly in a loaded, unactuated state with a feed-laden hopper assembly as indicated by a lowered flag. 
       FIG. 3  is a perspective view of the preferred embodiment of the anti-squirrel bird feeder with parts removed to show the drive mechanism assembly in a loaded, actuated state with a feed-laden hopper assembly as indicated by a lowered flag. 
       FIG. 4  is a perspective view of the preferred embodiment of the anti-squirrel bird feeder with parts removed to show the drive mechanism assembly in a load-free, unactuated state with a feed-barren hopper assembly as indicated by a raised flag. 
       FIG. 5  is a perspective view of the telescopic-operational assemblage with parts removed to show the hopper scale assembly. 
       FIG. 6  is a fragmentary perspective view of the inferior portion of the telescopic-operational assemblage, showing (1) the superior shaft member telescopically received in the inferior shaft member, (2) the hopper scale assembly, and (3) the latch assembly. 
       FIG. 7  is a fragmentary side view of the support assembly and push rod shaft assembly with parts removed to show the hopper scale assembly and depicting a feed-laden hopper assembly as indicated by a lowered flag. 
       FIG. 8(   a ) is a perspective view of the preferred embodiment of the anti-squirrel bird feeder with parts removed to show a feed-laden, full hopper assembly and the flag in a lowered state. 
       FIG. 8(   b ) is a perspective view of the preferred embodiment of the anti-squirrel bird feeder with parts removed to show a first near-empty state of the hopper assembly, the superior shaft member making contact with the flag pole. 
       FIG. 8(   c ) is a perspective view of the preferred embodiment of the anti-squirrel bird feeder with parts removed to show a second near-empty state of the hopper assembly, the superior shaft member raising the flag pole. 
       FIG. 8(   d ) is a perspective view of the preferred embodiment of the anti-squirrel bird feeder with parts removed to show a feed-barren, empty hopper assembly and the flag in a raised state. 
       FIG. 9  is a perspective view of the four-bar assembly in a relaxed, unactuated state showing a bar-joining junction assembly with exaggeratedly-spaced extension coil spring members. 
       FIG. 10  is a perspective view of the four-bar assembly of  FIG. 9  in a displaced, actuated state. 
       FIG. 11  is a perspective view of the telescopic-operational assemblage showing the four-bar assembly in a displaced, actuated state with parts removed to show the superior shaft bottom end juxtaposed in superior adjacency to the latch assembly. 
       FIG. 12  is an enlarged fragmentary perspective view of an inferior portion of the telescopic-operational assemblage with parts removed to show the latch assembly preventing further downward displacement of the superior shaft member. 
       FIG. 13  is a fragmentary side view of the superior end of the support member showing a support member shackle with parts removed to show a matter-receiving aperture. 
       FIG. 14  is a fragmentary side view of the support member length showing the flag assembly in a raised state. 
       FIG. 15  is a fragmentary side view of the junction of the inferior end of the support member and the superior end of the hopper scale assembly. 
       FIG. 16  is a fragmentary side view of the junction of the inferior end of the hopper scale assembly and the latch assembly with parts removed to show inner components of the latch assembly. 
       FIG. 17  is a side view of the hopper scale assembly showing the hopper scale assembly in a maximally displaced state. 
       FIG. 18  is a side view of the hopper scale assembly of  FIG. 17  showing the hopper scale assembly in an intermediately displaced state. 
       FIG. 19  is a perspective view of the preferred embodiment of the hopper assembly in a partially disassembled state. 
       FIG. 20  is a perspective view of the hopper assembly of  FIG. 19  in an assembled state. 
       FIG. 21  is an enlarged perspective view of the hopper assembly of  FIG. 20  showing a debris outlet screen. 
       FIG. 22  is a fragmentary perspective view of the hopper assembly being assembled with an inferior portion of the telescopic-operational assemblage (with parts removed) to show a latch pawl of the latch assembly in a retracted state to allow telescopic insertion of the hopper assembly into the anti-squirrel bird feeder. 
       FIG. 23  is a fragmentary perspective view of the hopper assembly in an assembled state with the inferior portion of the telescopic-operational assemblage (with parts removed) to show the latch pawl of the latch assembly in an extended state to maintain the hopper assembly in telescopic relation. 
       FIG. 24  is a top plan view of the hopper assembly. 
       FIG. 25  is a side plan view of the hopper assembly. 
       FIG. 26  is a cross-sectional view of the hopper assembly as shown in  FIG. 26 . 
       FIG. 27  is a bottom plan view of the hopper assembly. 
       FIG. 28  is a fragmentary perspective view of the shroud housing assembly in abridgement with the superior shaft member of the push rod shaft assembly. 
       FIG. 29  is a side perspective view of a vertically oriented telescopic-operational assemblage in an assembled state with a structurally minimized shroud housing assembly and a structurally minimized hopper assembly showing conjoined action of the shroud bridge and the spherical bearing to mitigate damage to the bird feeder caused by a large lateral load applied to the bird feeder. 
       FIG. 30  is a side perspective view of a vertically oriented telescopic-operational assemblage in an assembled state with a structurally minimized shroud housing assembly and a structurally minimized hopper assembly showing conjoined action of the shroud bridge and the spherical bearing to mitigate damage to the bird feeder from a large offset vertical load applied to the bird feeder. 
       FIG. 31  is an enlarged cross sectional side view of the spherical bearing of  FIGS. 29 and 30  showing the spherical bearing in a misaligned, damage-mitigating state. 
       FIG. 32  is a cross sectional side view of the spherical bearing in an aligned state. 
       FIG. 33  is a graphical representation of the four-bar spring assembly&#39;s supportable load (in pounds) as a function of the acute bar angle from vertical (in degrees). 
       FIG. 34  is a graphical representation of the four-bar spring assembly&#39;s vertical displacement of load (in inches) as a function of the acute bar angle from vertical (in degrees). 
       FIG. 35  is a graphical representation of the four-bar spring assembly&#39;s recovery spring deflection (in inches) as a function of the acute bar angle from vertical (in degrees). 
       FIG. 36  is a cross-sectional side view of an alternative embodiment of an empty anti-squirrel bird feeder as rested upon a ground plane showing an alternative drive assembly, an alternative shroud assembly, an alternative hopper assembly, and an alternative support assembly. 
       FIG. 37  is a cross-sectional perspective view of the alternative embodiment shown in  FIG. 36  as hung from a support structure. 
       FIG. 38  is a fragmentary perspective view of the alternative support assembly with parts broken away and alternative drive assembly in an unactuated state with alternative shroud bridge as shown in  FIG. 36 . 
       FIG. 38(   a ) is a fragmentary view of the inferior portions of the alternative support assembly with parts broken away as shown in  FIG. 38 . 
       FIG. 39  is a fragmentary perspective view of the alternative support assembly with parts broken away and alternative drive assembly in an actuated state with alternative shroud bridge as shown in  FIG. 36 . 
       FIG. 39(   a ) is a fragmentary view of the inferior portions of the alternative support assembly with parts broken away as shown in  FIG. 38 . 
       FIG. 40  is a fragmentary exploded perspective view of the alternative hopper assembly shown in  FIG. 36 . 
       FIG. 40(   a ) is a fragmentary perspective view of the alternative hopper assembly shown in  FIG. 36 . 
       FIG. 41  is a fragmentary exploded perspective view of the alternative shroud assembly shown in  FIG. 36 . 
       FIG. 41(   a ) is a fragmentary perspective view of the alternative shroud assembly shown in  FIG. 36 . 
       FIG. 42  is a fragmentary exploded perspective view of a hopper assembly extraction tool ejecting the hopper tray of the alternative hopper assembly. 
       FIG. 42(   a ) is a fragmentary perspective view of the hopper assembly extraction tool ejecting the hopper tray of the alternative hopper assembly as shown in  FIG. 42 . 
       FIG. 43  is a fragmentary exploded perspective view of a hopper assembly extraction tool inserting the hopper tray of the alternative hopper assembly. 
       FIG. 43(   a ) is a fragmentary perspective view of the hopper assembly extraction tool inserting the hopper tray of the alternative hopper assembly as shown in  FIG. 43 . 
       FIG. 44  is a perspective view of the hopper tray of the alternative hopper assembly as shown in  FIG. 36 . 
       FIG. 44(   a ) is a top plan view of the hopper tray of the alternative hopper assembly shown in  FIG. 44 . 
       FIG. 44(   b ) is a cross-sectional side view of the hopper tray of the alternative hopper assembly shown in  FIG. 44(   a ). 
   

   PREFERRED COMPONENT LISTING 
   
       
       Bird feeder  100 
       Support assembly  200 
           Hopper scale assembly  220 
               Pole-receiving structure  222     Support member  224     Support member shackle  225     Scale spring  226     Overload cable  227     Superior scale pin  228     Inferior scale pin  230     
               Flag assembly  240 
               Flag pole  242     Flag  244     Flag pin  246     
               Latch assembly  260 
               Latch body  262     Latch pawl  264     Latch spring  266     Latch spring retaining pin  268     
               
           Drive assembly  300 
           Four-bar spring assembly  320 
               Links  322     Spacers  324     Spacers  325     Spacer screws  326     Spacer nuts  328     Junction pins  330     Junction springs  332     Trunnion assemblies  334 
                   Trunnion rings  336     Shaft-receiving aperture  337 ( a )   Shaft-receiving aperture  337 ( b )   Trunnion pins  338     Trunnion set screw  340     
                   
               Push rod shaft assembly  360 
               Superior shaft member  361     Superior shaft top end  362     Superior shaft bottom end  366     Superior shaft length  364     Inferior shaft member  371     Inferior shaft top end  372     Inferior shaft bottom end  376     Inferior shaft length  374     Annular spring cup  384     Recovery spring  386     
               
           Shroud assembly  400 
           Shroud bridge assembly  420 
               Shroud bridge  422     Trim weight  424     Trim weight screws  426     Collar  428     
               Shroud housing assembly  440 
               Shroud cap  442     Spherical bearing  443     Shroud body  444     Perch assembly  460     Perch ring  462     Perch legs  464     
               
           Hopper assembly  500 
           Hopper body  502     Hopper cone  504     Hopper tray  506     Shaft-receiving sleeve  508     Hopper partitions  510     Anti-flick screen  512     Debris outlet screen  514     Feed outlet ports  516     Planar feed-supporting surface  518     Cylindrical feed-supporting surface  520     Hopper partition  522     
           
     
     
  
   
     
       
         
             
           
             
                 
             
             
               ADDITIONAL COMPONENT LISTING: 
             
             
                 
             
           
          
             
                 
             
          
         
         
             
             
             
          
             
                 
               Bird feeder 
               1000 
             
             
                 
               Snap ring 
               1004 
             
             
                 
               Slits 
               1005 
             
             
                 
               Integral Bushing member 
               1006 
             
             
                 
               Inferior conical section 
               1007 
             
             
                 
               Superior partition surface 
               1008 
             
             
                 
               Inferior partition surface 
               1009 
             
             
                 
               Hopper assembly extraction tool 
               1010 
             
             
                 
               Assembly support platform 
               1011 
             
             
                 
               Latch release means 
               1012 
             
             
                 
               Extension portion 
               1013 
             
             
                 
               Two-bar spring assembly 
               1020 
             
             
                 
               Medial bar 
               1030 
             
             
                 
               Lateral bar 
               1031 
             
             
                 
               Roller pin 
               1034 
             
             
                 
               Rollers 
               1035 
             
             
                 
               Mirror plane assembly 
               1040 
             
             
                 
               Step 
               1041 
             
             
                 
               Washer 
               1050 
             
             
                 
                 
             
          
         
       
     
   
   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring now to the drawings, the preferred embodiment of the present invention concerns anti-squirrel bird feeder  100 , which bird feeder  100  is generally illustrated and referenced in  FIGS. 1–4 , and  8 ( a )– 8 ( d ). Bird feeder  100  preferably comprises a number of sub-assemblies, namely, a telescopic-operational assemblage; a shroud assembly  400  as illustrated and referenced in  FIGS. 1–4 ,  8 ( a )– 8 ( d ), and  28 – 30 ; and a hopper assembly  500  as illustrated and referenced in  FIGS. 1–4 ,  8 ( a )– 8 ( d ),  19 – 27 ,  29  and  30 . The telescopic-operational assemblage preferably comprises a support assembly  200  as illustrated and referenced in  FIGS. 1–7 ,  8 ( a )– 8 ( d ),  11 , and  12 ; and a drive assembly  300  as illustrated and referenced in  FIGS. 1–5 ,  11 ,  29 , and  30 . Given the relatively large number of assemblies and subassemblies that comprise anti-squirrel bird feeder  100 , a brief description of each assembly along with identifying reference numerals is provided directly hereunder. 
   Support assembly  200  comprises a hopper scale assembly  220  as illustrated and referenced in  FIGS. 17 and 18 ; a flag assembly  240  as illustrated and referenced in  FIG. 14 ; and a latch assembly  260  as illustrated and referenced in  FIGS. 5–7 ,  11 ,  12 ,  16 ,  22 ,  23 ,  29 , and  30 . Hopper scale assembly  220  preferably comprises a hook, a support member  224  as illustrated and referenced in  FIGS. 1–8(   d ),  11 – 14 ,  22 ,  23 ,  29 , and  30 ; a support member shackle  225  as illustrated and referenced in  FIGS. 1–4 ,  8 ( a )– 8 ( b ), and  13 ; a scale spring  226  or scale spring means as illustrated and referenced in  FIGS. 5–7 ,  12 ,  15 – 18 ,  22 , and  23 ; an overload cable  227  as illustrated and referenced in  FIGS. 5–7 ,  12 ,  15 – 18 ,  22 , and  23 ; a superior scale pin  228  as illustrated and referenced in  FIG. 15 ; and an inferior scale pin  230  as illustrated and referenced in  FIG. 16 . Flag assembly  240  preferably comprises a flag pole  242  as illustrated and referenced in  FIGS. 1–4 ,  7 ,  8 ( a )– 8 ( d ) and  14 ; a flag  244  as also illustrated and referenced in  FIGS. 1–4 ,  7 ,  8 ( a )– 8 ( d ) and  14 ; and a flag pin  246  as illustrated and referenced in  FIG. 14 . Latch assembly  260  preferably comprises a latch body  262  as illustrated and referenced in  FIGS. 5–7 ,  11 ,  12 ,  16 ,  22 , and  23 ; a latch pawl  264  as also illustrated in  FIGS. 5–7 ,  11 ,  12 ,  16 ,  22 , and  23 ; a latch spring  266  as illustrated in  FIG. 16 ; and a latch spring-retaining pin  268  as illustrated in  FIG. 16 . 
   Drive assembly  300  comprises a four-bar spring assembly  320  as illustrated and referenced in  FIGS. 2 ,  3 ,  5 ,  9 – 11 ,  29 , and  30 ; and a push rod shaft assembly  360  as illustrated and referenced in  FIGS. 2 ,  3 ,  5 ,  11 ,  29 , and  30 . Four-bar spring assembly  320  preferably comprises a plurality of rigid links  322 ; a plurality of rigid spacers  324  and  325 ; a plurality of spacer screws  326 ; a plurality of spacer nuts  328 ; two rigid junction pins  330  or pivot attachment means; two four-bar springs or junction springs  332  or bar spring means; and two trunnion assemblies  334  as illustrated and referenced in  FIGS. 9 and 10 . Each trunnion assembly  334  preferably comprises a trunnion ring  336 , two collinear, laterally-spaced trunnion pins  338  and a trunnion set screw  340  as further illustrated in  FIGS. 9 and 10 . 
   Push rod shaft assembly  360  preferably comprises a superior shaft member  361  as illustrated and referenced in  FIGS. 1 ,  2 ,  4 – 8 ( d ),  11 ,  12 ,  22 ,  23 , and  29 ; an inferior shaft member  371  as illustrated and referenced in  FIGS. 5–7 ,  11 ,  12 ,  22 , and  23 ; an annular spring cup  384  as illustrated and referenced in  FIGS. 5 ,  11 , and  30 , and a recovery spring  386  as illustrated and referenced in  FIGS. 5 ,  11 , and  30 . Superior shaft member  361  comprises a superior shaft top end  362  as illustrated and referenced in  FIGS. 1 ,  2 ,  4 ,  5 ,  7 – 8 ( d ),  11 , and  28 – 30 ; a superior shaft bottom end  366  as illustrated and referenced in  FIGS. 5–7 ,  11 ,  12 ,  22 ,  23 ,  28 – 30 ; and a superior shaft length  364  as generally referenced in  FIG. 28 . Inferior shaft member  371  comprises an inferior shaft top end  372  as illustrated and referenced in  FIGS. 5 ,  6 , and  11 ; an inferior shaft bottom end  376  as illustrated and referenced in  FIGS. 6 and 12 ; and an inferior shaft length  374  as generally referenced in  FIG. 6 . 
   Shroud housing  400  comprises a shroud bridge assembly  420 ; a shroud housing assembly  440  as illustrated and referenced in  FIGS. 1–4 ,  8 ( a )– 8 ( d ), and  28 ; and a perch assembly  460  as illustrated and referenced in  FIGS. 1–4 ,  8 ( a )– 8 ( d ), and  28 . Shroud bridge assembly  420  preferably comprises a shroud bridge  422  as illustrated and referenced in  FIGS. 28–30 ; a trim weight  424  as illustrated and referenced in  FIG. 28 ; a plurality of trim weight screws  426 , one of which has been illustrated and referenced in  FIG. 28 ; a collar  428  as illustrated and referenced in  FIGS. 29 and 30 ; and a collar set screw (not specifically referenced). Shroud housing assembly  440  preferably comprises a shroud cap  442  as illustrated and referenced in  FIGS. 1–4 ,  8 ( a )– 8 ( d ), and  28 ; a shroud body  444  as also illustrated and referenced in  FIGS. 1–4 ,  8 ( a )– 8 ( d ), and  28 ; and a plurality of shroud screws. Perch assembly  460  preferably comprises a perch ring  462  or perch member as illustrated and referenced in  FIGS. 1–4 ,  8 ( a )– 8 ( d ), and  28 ; a plurality of perch legs  464  as also illustrated and referenced in  FIGS. 1–4 ,  8 ( a )– 8 ( d ), and  28 ; and a plurality of perch screws or perch member attachment means (not specifically referenced). 
   Hopper assembly  500  preferably comprises a hopper body  502  as illustrated and referenced in  FIGS. 1–4 ,  8 ( a )– 8 ( d ), and  19 – 26 ; a hopper cone  504  as illustrated and referenced in  FIGS. 1–4 ,  8 ( a )– 8 ( d ),  19 – 23 ,  25 , and  26 ; a hopper tray  506  as illustrated and referenced in  FIGS. 1–4 ,  8 ( a )– 8 ( d ),  19 – 23 , and  25 – 27 ; a shaft-receiving sleeve  508  as illustrated and referenced in  FIGS. 8(   b )– 8 ( d ),  19 – 24 ,  26 , and  27 ; a plurality of hopper partitions  510  as illustrated and referenced in  FIGS. 1–4 ,  8 ( a )– 8 ( d ),  19 – 24 , and  26 ; an anti-flick screen  512  as illustrated and referenced in  FIGS. 19 ,  20 ,  22 , and  23 ; and a debris outlet screen  514  as illustrated and referenced in  FIGS. 21–23 . 
     FIG. 1  illustrates the internal and external configuration of the assembled bird feeder apparatus  100  when the bird feeder&#39;s hopper is not empty. The cut outs enable the viewer to view the internal configuration. The viewer may wish to compare  FIG. 1  with  FIG. 4 . The viewer will note that the only difference between  FIG. 1  and  FIG. 4  is in the external configuration, namely the flag position.  FIG. 1  depicts flag  244  in a lowered position signaling to passersby that hopper assembly  500  is feed-laden (not empty) and  FIG. 4  depicts flag  244  in a raised state indicating to passersby that hopper assembly  500  is feed-barren (empty). 
     FIG. 3  illustrates the internal and external configuration of bird feeder apparatus  100  after the telescoping action has precluded access to hopper tray  506  due to the shroud load exceeding the a preset maximum (as caused by the added weight of an adult squirrel  104 ). The cut outs enable the viewer to view the internal configuration. The viewer should note that flag  244  is lowered, four-bar spring assembly  320  mechanism is collapsed, and access to hopper tray  506  is restricted. It will be further noted that in this state, the flag will be lowered regardless of the quantity of feed present in the hopper.  FIG. 2 , by comparison, illustrates the internal and external configuration of bird feeder apparatus  100  before the telescoping action has precluded access to hopper tray  506 .  FIG. 2  illustrates a minimal applied load (as caused by the added weight of two small birds  105 ) that does not exceed the preset maximum. The viewer should further note perch assembly  460  in  FIGS. 2 and 3 . 
     FIG. 5  illustrates the telescopic-operational assemblage (drive assembly  300  and support assembly  200  in an assembled state) that enables the telescoping action of shroud assembly  400  relative to hopper assembly  500 . The telescoping action both allows access to hopper tray  506  and restricts access to hopper tray  506 .  FIG. 6  illustrates how the bird feeder loads as referenced at  101  are transmitted through scale spring  226  to support member  224 . In addition,  FIG. 6  illustrates how overload cable  227  is slack when the scale spring load as referenced at  102  does not exceed the maximum load capacity of scale spring  226 . Vector  103  represents the tension in support member  224 . 
     FIG. 7  begins to illustrate how flag  244  is actuated. Due to the stretch of scale spring  226  with load  102 , drive assembly  300 , shroud assembly  400 , and hopper assembly  500  are displaced downwardly relative to support member  224 . The displacement depends on the weight of the seed or feed in hopper assembly  500 . As the noted assemblies slide down support member  224 , superior shaft member  361  also slides down support member  224 . The displaced assemblies thus lower the support that superior shaft member  361  provides flagpole  242 . Consequently, flag pole  242  pivots about its pivot axis extending through a flag pin  246  attaching flag pole  242  to support member  224 , thus lowering flag  244  from its upright position (empty hopper assembly) to its lowered position, indicating that hopper assembly  500  is feed-laden.  FIGS. 8(   a ) through  8 ( d ), in tandem, further illustrate the raising and lowering of flag  244  in a more detailed, step-by-step fashion at varying levels of emptiness. 
     FIG. 11  illustrates how superior shaft member  361  regulates the extent to which four-bar spring assembly  320  can compress when it collapses due to load  101 . As more clearly illustrated in the enlarged view in  FIG. 12 , superior shaft member  361  contacts latch body  262  latch thereby precluding further compression of four-bar spring assembly  320 . This regulation precludes four-bar spring assembly  320  from contacting shroud assembly  400  thereby possibly jamming the telescoping action. 
     FIG. 13–16  are provided to illustrate with greater clarity support assembly  200  with its subassemblies and various components, namely flag assembly  240  as illustrated in  FIG. 14 ; latch assembly  260  as illustrated in  FIG. 16 ; overload cable  227  as illustrated in  FIGS. 15 and 16 ; and support member shackle  225  as illustrated in  FIG. 13 . Noteworthy is that the support member shackle  225  is not threaded onto support member  224  but rather riveted such that support member shackle  225  can rotate freely precluding torsional loading of support member  224  and without becoming disjointed as can be the case with a threaded joint if not lock wired. 
     FIG. 17  generally illustrates the configuration of overload cable  227  when scale spring  226  is stretched to nearly its maximum.  FIG. 18  generally illustrates the configuration of overload cable  227  when scale spring  226  is in an intermediately displaced state. It should be noted here that with a small design change a compression spring could be in place of scale spring  226  and overload cable  227  thus eliminating the need for overload cable  227  since a compression spring would simply reach solid height if an excessive load were applied to shroud assembly  400 . Preferably, however, bird feeder apparatus  100  comprises scale spring  226  and overload cable  227  as described herein. 
     FIGS. 19–27  generally illustrate hopper assembly  500  in order to provide a clear picture to the viewer of its features.  FIGS. 21–23  generally illustrate debris outlet screen  514  comprising small apertures in hopper tray  506 , which debris screen  514  permits debris, but not feed, to fall out of hopper tray  506  thus precluding clogging of the feed outlet ports (as referenced at  516  in  FIGS. 19 ,  23 , and  26  in hopper assembly  500 .  FIG. 22  further illustrates how latch pawl  264  retracts (or is compressible) to permit insertion of hopper assembly  500  into bird feeder apparatus  100 .  FIG. 23  further illustrates how latch pawl  264  extends to capture hopper assembly  500  at the inferior surface of hopper tray  506  adjacent shaft-receiving sleeve  508  once hopper assembly  500  is fully inserted into bird feeder apparatus  100 . 
     FIG. 28  generally illustrates how shroud assembly  400  is bridged to superior shaft member  361  of push rod shaft assembly  360 .  FIG. 28  further illustrates trim weight  424 , the bridge corrugations which provide flexibility (as simplified and exaggerated in  FIGS. 29 and 30 ), and a spherical bearing  443  as illustrated and referenced in  FIGS. 28–32 . It will be seen from an inspection of the noted figures that spherical bearing  443  functions to preclude a bending moment from being applied to superior shaft member  361  either from misalignment or from a large offset load being applied to shroud assembly  400 .  FIG. 29  attempts to illustrate the conjoined action of shroud bridge  422  and spherical bearing  443  to mitigate damage to bird feeder apparatus  100 , particularly superior shaft member  361 , from a large lateral load (as referenced at  106 ) applied to bird feeder apparatus  100 .  FIG. 30  attempts to illustrate the conjoined action of shroud bridge  422  and spherical bearing  443  to mitigate damage to bird feeder apparatus  100 , particularly superior shaft member  361 , from a large offset vertical load (as referenced at  107 ) applied to bird feeder apparatus  100 . 
     FIGS. 33–35  are graphical representations of various features of bird feeder apparatus.  FIG. 33  is a graphical representation of the four-bar spring assembly&#39;s supportable load (in pounds) as a function of the acute bar angle from vertical (in degrees). The supportable load is referenced at  108  and comprises a heavy, nonlinear dotted line. The structural weight of bird feeder apparatus  100  is referenced at  109  and comprises a solid line. The recovery load is referenced at  110  and comprises a broken line comprising dots and dashes. The linear region is referenced at  111  and comprises a dotted line. The structural weight of bird feeder apparatus  100  combined with the weight of a typical adult squirrel (approximately 0.75 pounds) is referenced at  112  and comprises a broken line comprising dashes. The maximum supportable load is referenced at  113  and comprises a solid line.  FIG. 34  is a graphical representation of the four-bar spring assembly&#39;s vertical displacement of load (in inches) as a function of the acute bar angle from vertical (in degrees). The vertical displacement of load is referenced at  114  and comprises a heavy, nonlinear dotted line. The linear region is referenced at  115  and comprises a solid line.  FIG. 35  is a graphical representation of the four-bar spring assembly&#39;s recovery spring deflection (in inches) as a function of the acute bar angle from vertical (in degrees). 
   More particularly, support assembly  200  preferably comprises hopper scale assembly  220 ; flag assembly  240 ; and hopper attachment means. The hopper attachment means are preferably defined by latch assembly  260 . Hopper scale assembly  220  preferably comprises rigid support member  224  or support member, feeder support attachment means, scale spring  226 , overload cable  227 , and scale spring attachment means. It is contemplated that the feeder support attachment means may preferably be defined by a hook or similar other removable fastening means for attaching the superior most end of support member  224  to a bird feeder support structure (such as the limb of a tree or a bird feeder stand). The feeder support attachment means are cooperatively associated with support member shackle  225  for attaching the superior most end of support member  224  to a bird feeder support structure. 
   Preferably, the superior most end of support member may further comprise support member shackle  225 . Noteworthy is that support member shackle  225  is preferably not threaded onto support member  224 , but rather riveted such that it can rotate freely precluding torsional loading of support member  224  and without becoming disjointed as can be the case with a threaded joint if not lock wired. The hook or similar other removable fastening means may then be removably joined to support member shackle  225  for attaching the superior most end of support member  224  to a bird feeder support structure. A superior scale pin  228  and an inferior scale pin  230  may preferably define the scale spring attachment means. The superior most end of support member  224 , to which the hook may attach, may properly be referred to as a superior member end. Opposite the superior member end is an inferior member end. A support member length extends intermediate the superior and inferior member ends. 
   Hopper scale assembly  226  preferably comprises scale spring  226  of an extension coil type and overload cable  227 . It should be noted here that with a small design change a compression spring could be used eliminating the need for overload cable  227  since a compression spring would simply reach solid height if an excessive load were applied to shroud assembly  400 . Scale spring  226  preferably comprises a superior spring end and an inferior spring end. The superior spring end is preferably fixedly attached to the inferior member end as generally depicted in  FIG. 15 . It will be seen from an inspection of  FIG. 15  that superior scale pin  228  functions to fixedly attach the superior spring end to the inferior member end. The inferior spring end is preferably fixedly attached to the hopper attachment means. It will be seen from an inspection of  FIG. 16  that inferior scale pin  230  functions to fixedly attach the inferior spring end to the hopper attachment means. 
   In the preferred embodiment, anti-squirrel bird feeder  100  preferably comprises feed gauge means for indicating the quantity of feed in hopper assembly  500 . The feed gauge means may preferably be defined by flag assembly  240 . In this regard, it should be noted that support member  224  further preferably comprises pole-receiving structure  222  as illustrated and referenced in  FIG. 14 . Pole-receiving structure  222  may preferably be defined by a pole receiving slot or notch formed in support member  224  in the support member length. Preferably, pole-receiving structure  222  is spatially located or formed intermediate the superior member end and the inferior member end so that when anti-squirrel bird feeder  100  is in an assembled state, pole-receiving structure  222  is critically positioned, a more thorough description of which may be found in later specifications hereinafter. Flag assembly  240  preferably comprises flag pole  242 , flag  244 , and pole attachment means, which pole attachment means may preferably be defined by flag pin  246 . It will be seen from an inspection of  FIG. 14  that flag pole  242  further comprises a flag end and a pole attachment end. The pole attachment means or flag pin  246  attach the pole attachment end to pole-receiving structure  222  and flag  244  is attached to the flag end for indicating to the user or passersby the quantity of feed in hopper assembly  500 . 
   As earlier specified, the hopper attachment means are preferably defined by latch assembly  260 . Latch assembly  260  preferably comprises latch body  262 , latch pawl  264 , latch spring  266 , and latch pin. It will be understood from an inspection of  FIG. 16  that the latch pin is essentially defined by the inferior scale pin  230 . It will be further understood from an inspection of  FIG. 16  that latch pawl  264  and latch spring  266  (which preferably is a compression type coil) together function as a spring-loaded latch pawl. The spring loaded latch pawl is thus compressible from its equilibrium position for releasing hopper assembly  500  from telescopic relation with the shroud body of shroud assembly  400 . Further, latch spring  266  is releasable from its compressed state and thus extendable (as it is restored to its equilibrium position) for maintaining hopper assembly  500  in telescopic relation to the shroud body of shroud assembly  400  as generally depicted in  FIG. 23 . Arrow  102  in  FIGS. 5–7 ,  11 , and  12  depicts the force vector directed at latch pawl  264  when hopper assembly  500  is in telescopic relation with shroud body  444  of shroud assembly  400 . Latch pin  230  functions to fixedly attach the inferior spring end to latch assembly  260  as illustrated in  FIG. 16 . It will thus be seen that latch assembly  260  or hopper attachment means provide bird feeder apparatus  100  with a so-called “drop-out” hopper assembly for enabling users thereof to easily clean and refill the hopper assembly. 
   Drive assembly  300  preferably comprises four-bar spring assembly  320 , and a push rod shaft assembly  360 . Four-bar spring assembly  320  preferably comprises a medial superior bar  30 , a lateral superior bar  31 , a medial inferior bar  32 , a lateral inferior bar  33 , a bar-joining junction assembly, a superior trunnion assembly  34 , and an inferior trunnion assembly  35  as illustrated and referenced in  FIGS. 9 and 10 . Medial and lateral superior bars  30  and  31  each comprise two rigid, linear link members  322  spaced in parallel relation to one another. Medial superior bar  30  preferably comprises a first short spacer  324  and lateral superior bar  31  preferably comprises a first long spacer  325 . The first long spacer  325  functions to space the link members  322  of lateral superior bar  31  farther apart than the spacing between the link members  322  of medial superior bar  30 . Medial and lateral superior bars  30  and  31  each comprise a superior top bar end and an inferior top bar end. The superior top bar end of medial superior bar  30  is preferably aligned with the superior top bar end of lateral superior bar  31  such that the superior top bar end of medial superior bar  30  is medial to the superior top bar end of lateral superior bar  31 . In other words, the spacing between the link members  322  of medial superior bar is less than the spacing between the link members  322  of lateral superior bar such and thus medial superior bar may be medially aligned with respect to lateral superior bar. 
   Medial and lateral inferior bars  32  and  33  each comprise a superior bottom bar end and an inferior bottom bar end. In a similar fashion to medial and lateral superior bars  30  and  31 , medial and lateral inferior bars  32  and  33  each comprise two rigid, linear link members  322  spaced in parallel relation to one another. Medial inferior bar  32  preferably comprises a second short spacer  324  and lateral inferior bar  33  preferably comprises a second long spacer  325 . The second long spacer  325  functions to space the link members  322  of lateral inferior bar  33  farther apart than the spacing between the link members  322  of medial inferior bar  32 . Medial and lateral inferior bars  32  and  33  each comprise a superior bottom bar end and an inferior bottom bar end. The inferior bottom bar end of medial inferior bar  32  is preferably aligned with the inferior bottom bar end of lateral inferior bar  33  such that the inferior bottom bar end of medial inferior bar  32  is medial to the inferior bottom bar end of lateral inferior bar  33 . In other words, the spacing between the link members  322  of medial inferior bar  32  is less than the spacing between the link members  322  of lateral inferior bar  33  such that medial inferior bar  32  may be medially aligned with respect to lateral inferior bar  33 . 
   Superior trunnion assembly  34  functions to pivotally connect medial and lateral superior bars  30  and  31  at the superior top bar ends as generally depicted in  FIGS. 9 and 10 . Further, inferior trunnion assembly  35  functions to pivotally connect medial and lateral inferior bars  32  and  33  at the inferior bottom bar ends as also generally depicted in  FIGS. 9 and 10 . Superior and inferior trunnion assemblies  34  and  35  thus form a superior trunnion junction and an inferior trunnion junction. Both superior trunnion assembly  34  and inferior trunnion assembly  35  preferably comprise a trunnion ring  336 , two trunnion pins  338  extending laterally from the respective trunnion ring  336  along a respective pivot axis, and a trunnion set screw  340  all as illustrated and referenced in  FIGS. 9 and 10 . It will be seen that trunnion rings  336  of superior trunnion assembly  34  and inferior trunnion assembly  35  each comprise a shaft-receiving aperture. The superior shaft receiving aperture is referenced at  337 ( a ) in  FIGS. 9 and 10  and the inferior shaft-receiving aperture is referenced at  337 ( b ) in  FIG. 10 . Superior shaft receiving aperture  337 ( a ) is sized and shaped to receive superior shaft member  361  and inferior shaft-receiving aperture  337 ( b ) is sized and shaped to receive inferior shaft member  371 . It will be noted that superior shaft member  361  preferably comprises an outer diameter that is sized and shaped to be telescopically received in the inner diameter of inferior shaft member  371 . It will thus be further noted that superior shaft-receiving aperture  337 ( a ) preferably comprises a diameter of lesser magnitude than the diameter of inferior shaft-receiving aperture  337 ( b ). 
   The junction assembly preferably comprises first and second junction pins  330  or pivot attachment means, and first and second junction springs  332  or bar spring means. First junction pin  330  pivotally connects the inferior top bar end of lateral superior bar  31  to the superior bottom bar end of medial inferior bar  32 . Similarly, second junction pin  330  pivotally connects the inferior top bar end of medial superior bar  30  to the superior bottom bar end of lateral inferior bar  33 . It will be readily understood from an inspection of  FIGS. 9 and 10  that junction pins  330  each comprise opposite spring-engaging ends and that in the preferred embodiment as illustrated, the first and second junction pins  330  are preferably parallel to one another. In this last regard, it is important to note that junction pins  330  having a relaxed or unactuated parallel distance as generally depicted in  FIGS. 1 ,  2 ,  4 ,  5 ,  8 ( a )– 8 ( d ),  9 , and  29 ; and a displaced or actuated parallel distance as generally depicted in  FIGS. 3 ,  10 ,  11 , and  30 . 
   First and second junction springs  332  preferably comprise extension coil type springs and function to connect the spring-engaging ends of junction pins  330 . From an inspection of  FIG. 9 , it will be seen that first and second junction springs  332  essentially define the relaxed parallel distance when junctions springs  332  are relaxed in an unextended state or equilibrium state and further define the displaced parallel distance when displaced or in an extended, non-equilibrium state. Medial and lateral superior bars  30  and  31  thus have a first angle therebetween at the superior trunnion junction and medial and lateral inferior bars  32  and  33  have a second angle therebetween at the inferior trunnion junction. If four-bar spring assembly  320  is properly constructed or assembled, the first angle and the second angle are preferably equal in magnitude to one another (whether in a relaxed state or in a displaced state). Thus, four-bar spring assembly  320  provides a nonlinear, geometrically-based, closure mechanism, which mechanism is driven or displaced by external load forces acting through rigid superior and inferior bars  30 – 33  and which mechanism is countered or restored by restorative forces injunction springs  332 . It should be noted that the connectivity between superior shaft member  361 , inferior shaft member  371 , and drive assembly  300  via trunnion rings  336  provide for a secondary function of four-bar spring assembly  320 , which secondary function is to maintain alignment between the shroud body  444  and hopper assembly  500  should their cross-sections be different then round, i.e., rectangular, and thusly, to prevent jamming between shroud body  444  and hopper assembly. 
   Junction springs  332  produce a supportable load  108  as graphically represented in  FIG. 33 . Any time the supportable load  108  is greater than the applied load the four-bar mechanism or four-bar spring assembly  320  will open or become displaced.  FIG. 34  is a graphical representation of the four-bar spring assembly&#39;s vertical displacement of load (in inches) as a function of the acute bar angle from vertical (in degrees). The two basic geometric states of four-bar spring assembly, namely, closed (relaxed) and open (displaced) are respectively illustrated in  FIGS. 9 and 10 . 
   Push rod shaft assembly  360  preferably comprises superior shaft member  361 , inferior shaft member  371 , annular spring cup  384 , and recovery spring  386 . Superior shaft member  361  comprises superior shaft top end  362 , superior shaft bottom end  366 , and superior shaft length  364  intermediate superior shaft top and bottom ends  362  and  366 . Inferior shaft member  371  comprises inferior shaft top end  372 , inferior shaft bottom end  376 , and inferior shaft length  374  intermediate inferior shaft top and bottom ends  372  and  376 . The superior and inferior trunnion assemblies  334  each comprise shaft-receiving aperture  337  and shaft-fastening means. Shaft-receiving apertures  337  are sized and shaped to receive superior and inferior shaft lengths  364  and  374 , such that superior shaft bottom end  366  is telescopically received in inferior shaft top end  372 . The shaft-fastening means (or trunnion set screws  340 ) preferably fasten superior and inferior trunnion assemblies  334  to the superior and inferior shaft lengths  364  and  374  as generally depicted in  FIGS. 5 and 11 . Annular spring cup  384  is preferably affixed to the inferior shaft member  371  adjacent inferior shaft top end  372  and recovery spring  386  is seated upon spring cup  384  intermediate spring cup  384  and superior trunnion assembly  334  such that superior shaft length  364  extends through recovery spring  386 . In other words, recovery spring  386  encircles superior shaft length  364 , which superior shaft length  364  may be telescopically received in inferior shaft length  374  during displacement of the four-bar spring mechanism or four-bar spring assembly  320 . It is contemplated that recovery spring  386  functions to provide additional restorative spring force to the otherwise displaced four-bar spring assembly  320 . In this regard, recovery spring  386  is preferably a compression coil type spring.  FIG. 35  is a graphical representation of the four-bar spring assembly&#39;s recovery spring deflection (in inches) as a function of the acute bar angle from vertical (in degrees). 
   Shroud assembly  400  preferably comprises shroud bridge assembly  420 ; shroud housing assembly  440 ; and perch assembly  460 . Shroud bridge assembly  420  preferably comprises a substantially circular, corrugated shroud bridge  422 , trim weight  424 , trim weight screws  426 , collar  428 , and collar fastening means, or a collar set screw. Shroud housing assembly  440  preferably comprises a substantially cylindrical shroud body  444 , conical shroud cap  442  and bridge attachment means. The bridge attachment means may preferably be defined by a plurality of shroud screws. Shroud body  444  preferably comprises a superior shroud end, an inferior shroud end, a shroud body diameter or body periphery, and a shroud length intermediate the superior and inferior shroud ends. Shroud bridge  422  is preferably attached to shroud body  444  adjacent the superior shroud end. Superior shaft length  364  is received in collar  428  adjacent superior shaft top end  362  as illustrated in  FIGS. 28–30  and the collar fastening means or collar set screw secures superior shaft length  364  adjacent superior shaft top end  362  to shroud bridge  422 . Alternatively, shroud bridge  422  may be integrally formed with superior shaft length as a means to reduce production costs. 
   Shroud cap  442  preferably comprises a superior cap surface, an inferior cap surface, a basal cone diameter or basal periphery, and a superior shaft-receiving aperture extending from the superior cap surface to the inferior cap surface. The basal cone diameter or basal periphery is preferably greater in magnitude than the shroud body diameter or body periphery so as to provide some degree of cover to shroud body  444  as well as perched birds. Superior shaft top end  362  preferably extends upwardly from the push rod-receiving aperture as seen from a general inspection of  FIGS. 1–4 ,  8 ( a )– 8 ( d ), and  28 – 30 . Shroud cap  442  may be further defined wherein the superior shaft-receiving aperture comprises spherical bearing  443 . Spherical bearing  443  functions to allow the bird feeder apparatus to withstand unbalanced load forces directed against either shroud assembly  400  or hopper assembly  500 . 
   The slope of shroud cap  442  is preferably made shallow, but steep enough to shed rain and in most cases snow. Further, its overhang is preferably relatively small. A steeply sloped roof and/or a large overhang is neither desirable aesthetically, nor desirable functionally. An intuitive probability that a squirrel will be defeated if he attempts access to hopper tray  506  from the roof is 0.99, so shroud cap  442  of the preferred embodiment has a slope of approximately 15 degrees and an overhang of about 0.75 inches. 
   Perch assembly  460  preferably comprises perch ring  462  or perch member, a plurality of circumferentially spaced perch legs  464 , and ring attachment means or member attachment means. The ring attachment means may preferably be defined by comprising a plurality of perch screws or perch member attachment means. Preferably, it is contemplated that perch assembly  460  comprise three perch legs  464  spaced about 120 rotational degrees from one another, extending from perch ring  462  to shroud body  444 . It will be seen from an inspection of  FIGS. 1–4  that perch ring  462  has a ring diameter, which ring diameter is preferably greater in magnitude than the tray diameter. The ring attachment means or perch screws fixedly attach perch ring  462  to shroud body  444  concentrically adjacent hopper tray  506  (described in more detail hereinafter). The fixedly attached perch ring  462  thus enables birds to perch and feed from hopper tray  506 . 
   Hopper assembly  500  preferably comprises a substantially cylindrical hopper body  502 , a substantially frustoconical hopper cone  504 , hopper tray  506 , a plurality of vertical hopper partitions  510 , and shaft-receiving sleeve  508 . Notably, shaft-receiving sleeve  508  comprises a sleeve diameter, which sleeve diameter is sized and shaped to telescopically receive inferior shaft member  371 . It should be recalled that inferior shaft member  371  has a shaft diameter sized and shaped to telescopically received superior shaft member  361  and superior shaft member has a shaft diameter sized and shaped to receive or encircle support member  224 . 
   It will be seen that hopper body  502  comprises a superior hopper body end, an inferior hopper body end, and a hopper body diameter. Notably, the hopper body diameter is lesser in magnitude than the shroud body diameter so as to effect a proper telescopic relation with low probability of jamming. Hopper cone  504  preferably comprises a superior cone end and an inferior cone end. The superior cone end has a superior cone diameter and the inferior cone end has an inferior cone diameter. It will be seen that the superior cone diameter is preferably substantially equal in magnitude to the hopper body diameter and that the inferior cone diameter is preferably lesser in magnitude than the superior cone diameter. In this regard, the superior cone end is preferably fixedly and concentrically attached to the inferior hopper body end. The inferior cone end preferably comprises spacer-attachment means, a series of circumferentially spaced projections extending dowwardly from the inferior cone end, which projections may be riveted or otherwise fastened to hopper tray  506 . The circumferentially spaced projections define a series of feed outlet ports  516  or hopper ports. Feed outlet ports  516  preferably comprise a port width of approximately the length of the longest linear dimension of two sunflower seeds placed end to end. This sizing helps seed of feed flow into hopper tray  506  by inhibiting clogging. Feed outlet ports  516  further preferably comprise a port height of approximately the height of a cylinder that intersects the cone of repose for a generic seed aggregate. This height is primarily dependent on the ID of the hopper&#39;s cone at the top of the ports; therefore, an iterative process determines this height. This sizing helps feed or seed flow into hopper tray  506 . 
   Hopper tray  506  preferably comprises a substantially planar feed-supporting surface  518  as illustrated and referenced in  FIGS. 22 and 23 ; and a substantially cylindrical feed-supporting surface  520  as also illustrated and referenced in  FIGS. 22 and 23 . It will be seen from an inspection of the noted figures that cylindrical feed-supporting surface  520  extends orthogonally upward from planar feed-supporting surface  518 . Thus, cylindrical feed-supporting surface  520  has both a feed-supporting height and a feed-supporting diameter. The feed-supporting diameter is preferably greater in magnitude than the inferior cone diameter. As earlier described, the spacer-attachment means fixedly and concentrically attach hopper tray  506  to the inferior cone end in spaced relation thereto. It will be understood that the spacer-attachment means have a feed outlet height, which feed outlet height is preferably substantially equal in magnitude to the feed-supporting height. 
   The vertical hopper partitions  510  radially extend from the inner surface of hopper body  502  to shaft-receiving sleeve  508  for maintaining shaft-receiving sleeve  508  in concentric relation with hopper body  502 . Vertical hopper partitions  510  further define a plurality of feed-receiving compartments within hopper body  502  and hopper cone  504 . The feed-receiving compartments each preferably comprise a substantially uniform feed-receiving volume as is generally depicted in  FIGS. 8(   a )– 8 ( d ). After filling or checking the fill level of the feed-receiving compartments, the user may assemble hopper assembly  500  with the remaining sub-assemblies. Hopper assembly  500  may thus be telescopically received within shroud body  444 . When in an assembled state, inferior shaft length  374  extends through shaft-receiving sleeve  508  and scale assembly  220  extends through push rod shaft assembly  360 . The inferior spring end is fixedly attached to the hopper attachment means, which hopper attachment means function to maintain hopper assembly  500  in telescopic relation to shroud body  444 . 
   It should be noted that the surround perch or perch assembly  460  parallels the outer periphery of the cross-section of shroud body  444 , but it is offset laterally and away from shroud body  444  by approximately 1.5 inches. This offset provides ample room for birds up to the size of approximately a cardinal, but inhibits larger birds. To accommodate larger and smaller birds, it is contemplated that inner and outer adjacent perches could be provided. The plane of perch assembly  460  parallels the plane of planar feed-supporting surface  518 , but is offset approximately 0.5 inches below feed-supporting surface  518 . This offset makes it easier for birds to acquire seed or feed from hopper tray  506 . 
   Hopper assembly  500  may further preferably comprise an inverted, conical hopper partition  522  or inverted, sloped hopper partition as illustrated and referenced in  FIGS. 1 ,  2 ,  4 ,  8 ( a )– 8 ( d ),  19 – 23 ,  24 , and  26 . Hopper partition  522  preferably comprises a superior partition surface, an inferior partition surface, a superior partition diameter, and an inferior partition diameter. It will be seen from an inspection of  FIGS. 22 and 23  that the inferior partition diameter is substantially equal in magnitude to the sleeve diameter and that the superior partition diameter is preferably lesser in magnitude than the shroud body diameter. The superior partition surface thus provides an omnidirectional guide for guiding inferior shaft bottom end  376  into shaft-receiving sleeve  508  when hopper assembly  500  is telescopically received in shroud body  444 . While the superior partition surface provides an omnidirectional guide for guiding inferior shaft bottom end  376  into shaft-receiving sleeve  508  when hopper assembly  500  is telescopically received in shroud body  444 , the inferior partition surface functions to preclude feed from occupying the clear space required by the four-bar mechanism or four-bar spring assembly  320  so that four-bar spring assembly  320  can freely collapse without feed interference. In this last regard, the reader may wish to compare  FIGS. 2 and 3 . The reader will thus see that four-bar spring assembly  320  when collapsed (as in  FIG. 3 ) requires a certain clear space afforded by hopper partition  522 .  FIG. 3  thus does not specifically reference hopper partition  522  because of spatial concerns. The inferior partition surface further permits the user to maximize the feed capacity of hopper assembly  500  as has been generally depicted in  FIG. 8(   a ). 
   Hopper assembly  500  may further preferably comprise an anti-flick grating or anti-flick screen  512 . Anti-flick screen  512  preferably extends radially from the inferior cone end to cylindrical feed-supporting surface  520  and functions to prevent birds from flicking feed from hopper tray  506 . It is contemplated that the anti-flick grating or anti-flick screen  512  preferably comprises a pitch of approximately 0.5 inches. This size of mesh or grating allows ample room to acquire seed from the seed tray but inhibits a bird&#39;s ability to slew its beak through the seeds with the consequence of flicking seeds out of hopper tray  506  resulting in substantial loss of seed. 
   If anti-flick screen  512  is incorporated into the design, it is further contemplated that the hopper assembly  500  may further preferably comprise debris outlet means. When anti-flick screen  512  is used, debris tends to accumulate in hopper tray  506 , which accumulation eventually inhibits the feed or seed from properly flowing out of the hopper ports or feed outlet ports  516 . The debris outlet means may preferably be defined by a debris outlet screen  514 , which debris outlet screen  514  essentially forms the outer annular portions of planar feed-supporting surface  518  as most clearly illustrated in  FIGS. 22 and 23 . It will be seen from an inspection of  FIGS. 22 and 23  that debris outlet screen  514  is essentially an apertured portion of planar feed supporting surface  518 . Debris outlet screen  514  preferably comprises a square mesh that has a pitch of approximately 0.03125 inches. This size of mesh allows debris to fall from the hopper tray  506 , precluding its accumulation and clogging of feed outlet ports  516 . It will thus be understood that the partitioned, removable (drop out) hopper assembly  500  allows (1) segregation of feed or seed types in the feed-receiving compartments and (2) easy cleaning and easy refilling as enabled by the selectively removable (drop out) features. 
   As earlier specified, the support member length preferably comprises pole-receiving structure  222 , which pole-receiving structure  222  is critically located. In this regard, it should be noted that pole-receiving structure  222  is preferably spatially located adjacent superior shaft top end  362 . For descriptive purposes, assume that hopper assembly  500  is filled with a quantity of feed as generally illustrated in  FIG. 8(   a ). The quantity of feed in hopper assembly  500  when in a full state, will necessarily comprise a maximum feed load as has been generally depicted in  FIG. 8(   a ) with a pointed lead line and referenced at numeral  116 . At maximum feed load  116 , scale spring  226  is maximally displaced as generally depicted in  FIG. 17 . As birds feed from anti-squirrel bird feeder  100 , the feed load will decrease, resulting in restorative displacement of scale spring  226 . Hopper assembly  500 , shroud assembly  400 , and drive assembly  300  necessarily experience incremental displacements (however infinitesimal) back toward the minimum displacement of scale spring  226  when hopper assembly is empty as generally depicted in  FIGS. 8(   a ) through  8 ( d ). While it is noted that the preferred vertical displacement is dependent upon the combined weight of hopper assembly  500 , the feed load, the stiffness of scale spring  226 , and the clearance between the superior shaft member&#39;s internal diameter and flagpole  242 , the preferred vertical displacement, or total displacement between maximum and minimum displacement is preferably about 1.25 inches or on this order of magnitude. From an inspection of  FIGS. 8(   a ) through  8 ( d ), it will be seen that as hopper assembly  500  nears an empty state, the superior shaft top end  362  operates to raise flag pole  242  and flag  244 . In this regard, it will be noted that scale spring  226  and the feed load operate to displace hopper assembly  500 , shroud assembly  400 , and drive assembly  300  relative to support member  224 . It will thus be further understood that pole-receiving structure  222  is critically located in the support member length such that superior shaft member  361  will mechanically raise or lower flag pole  242  (which flag pole  242  depends from the pole-receiving structure  522 ) according to the feed load and the accordant displacement of scale spring  226 . Thus, flag assembly  240  functions to effectively indicate the relative quantity of feed in hopper assembly  500  as dictated by the remaining feed load or feed weight and displacement of scale spring  226 . 
   It should be noted that the primary parameter of the present invention is the stroke of the telescoping mechanism. In the preferred embodiment, the stroke is approximately 1.75 inches. This stroke was chosen because it provides ample space for feeding birds to acquire the feed or seed yet keeps consequential dimensions, as explained below, within acceptable limits. 
   As a consequence of the stroke chosen, the bars of four-bar spring assembly  320  or four-bar closure mechanism need to be approximately 3.125 inches long. This dimension then governs the minimum characteristic diameter of the shroud (the largest diameter of a circle that is enclosed by the shroud&#39;s cross-section), approximately 6.375 inches: two bar lengths plus a tolerance is required when the four-bar mechanism is collapsed. An additional consequence of the stroke chosen accrues to the length of the body of the shroud, for the shroud must provide enough free space to accommodate the load free height of the four-bar mechanism in addition to completely shrouding hopper assembly  500  when the telescoping action has closed access to hopper tray  506 . Therefore, the preferred length of shroud body  444  is approximately 9.5 inches. The aforementioned dimensions of shroud body  444  accommodate a hopper assembly having approximately a height of about 6 inches and approximately a diameter of 5.5 inches. The hopper assembly  500 , therefore, stores enough seed or feed to feed five or six ravenous sparrows for about three days. 
   The aspect ratio of the bird feeder, its shroud&#39;s body height to its shroud&#39;s characteristic diameter, can be decreased for aesthetic reasons and for increasing the hopper storage capacity. As long as the minimum characteristic diameter of the bird feeder&#39;s shroud is not violated, its diameter can be whatever one desires. Note that the larger the characteristic diameter, the greater the hopper&#39;s storage capacity can be made. 
   ALTERNATIVE EMBODIMENT(S) 
   It is contemplated that further alternative embodiment(s) of the anti-squirrel bird feeder are substantially similar to anti-squirrel bird feeder  100  save for five broad-based modifications, as discussed in more detail hereinafter. The further contemplated alternative embodiment(s) of the anti-squirrel bird feeder shall be hereinafter designated as bird feeder  1000  as is generally referenced in  FIGS. 36 and 37 , and which alternative bird feeder incorporates the modifications hereinafter specified in their entirety for ease of understanding. 
   Modification No. 1: 
   Bird feeder  1000  requires no fasteners. This reduces labor costs in production and simplifies owner assembly, disassembly, and cleaning of the birdfeeder. In this regard, shroud housing assembly  440  is unchanged from a parts perspective with the exception of trim weight screws  426  which are no longer deemed necessary. In bird feeder  1000 , shroud body  444  simply sits or rests upon shroud bridge  422  as generally depicted in  FIG. 37 . It will be seen from a close inspection of  FIG. 37  that shroud bridge  422  may be integrally formed with push rod shaft assembly  360  adjacent superior shaft top end  362 . It will be further noted from an inspection of  FIGS. 36 and 37  that shroud body  444  comprises an upper body flange  1001  as illustrated and referenced in  FIGS. 36 ,  37 , and  41 . It will be understood from an inspection of the noted figures that flange  1001  extends radially inward at the superior/upper end of shroud body  444  so that the innermost diameter of shroud body  444  (as achieved via flange  1001 ) is lesser in magnitude than the outermost diameter of shroud bridge  422  and thus rests upon shroud bridge  422  when bird feeder  1000  is hung from a support structure  1003  as depicted in  FIG. 37 .  FIG. 36 , alternatively, shows bird feeder  1000  as rested upon a ground plane  1002 . It will be seen from a comparative inspection of  FIGS. 36 and 37  that flange  1001  of shroud body  444  becomes spaced from shroud bridge  422  when bird feeder  1000  is rested upon ground plane  1002  and further rests upon shroud bridge  422  when bird feeder  1000  is hung from support structure  1003 . Shroud cap  442  sits or rests upon flange  1001  of shroud body  444  in either scenario as may be seen from a further inspection of  FIGS. 36 and 37 . Notably, trunnion assembly  334  may also be integrally formed with superior shaft length  364  of push rod shaft assembly  360 . 
   Close tolerancing of an integral bushing member  1006  of shroud cap  442 , which bushing member  1006  mates with (slides over) superior shaft top end  362  of push rod shaft assembly  360 , ensures adequate alignment between shroud housing assembly  440  and hopper assembly  500  by precluding significant rotation of the shroud cap  442  about any of its lateral axes (infinite in number) and by the promotion of binding between the integral bushing member  1006  and the superior shaft top end  362 . These effects conjoin to preclude separation of the interface between the flange  1001  and the shroud bridge  422  and thereby ensure adequate alignment between the shroud housing assembly  440  and the hopper assembly  500  when birdfeeder  1000  is asymmetrically loaded. Additionally, this alternate assembly method also provides easy access to trim weight  424  if adjustment is required. Bushing member  1006  is generally referenced in  FIGS. 36 ,  37 ,  41 , and  41 ( a ). 
   Modification No. 2: 
   Hopper assembly  500  is unchanged from a parts perspective with the exception of the addition of a snap ring  1004  as illustrated and referenced in  FIG. 40 . It is contemplated that snap ring  1004  may preferably be constructed from spring steel, such as piano wire or similar other material. Snap ring  1004  functions to hold the entire hopper assembly  500  together. In this regard, vertical hopper partitions  510 , which extend radially outward and downward from hopper partition  522 ( a ) (alternatively reduced in size as compared to hopper partition  522  and referenced in  FIGS. 36 ,  37 ,  40 , and  40 ( a )), protrude through hopper tray  506  as generally depicted in  FIGS. 36 ,  37 ,and  40 . Snap ring  1004  engages slits  1005  alternatively formed in hopper partitions  510 , one of which slit  1005  has been referenced in each of  FIGS. 36 ,  37 ,  40 , and  40 ( a ). Slits  1005  are spatially situated in each hopper partition  510  such that when hopper assembly  500  is assembled, slits  1005  are exposed in inferior adjacency to the inferior surface or bottom surface of hopper tray  506 . Consequently, the various components of hopper assembly  500  are captured together by snap ring  1004  as snap ring  1004  is received in slits  1005 . This assembly alternative simplifies owner cleaning by providing easy access to all surfaces of hopper assembly  500 . This is a result of complete and simple assembly and disassembly of the hopper assembly  500 . 
   Modification No. 3: 
   It is further contemplated that hopper tray  506  may alternatively comprise an inferior conical section  1007  as illustrated and referenced in  FIGS. 36 ,  37 , and  40 – 44 ( b ). Inferior conical section  1007  incorporates three notable attributes. Firstly, inferior conical section  1007  comprises a slope that is steeper than the angle of repose of the feed mixture. This feature promotes egress of the feed from hopper assembly  500 . Secondly, inferior conical section  1007  functions to allow latch assembly  260  to be retracted in inferior adjacency to inferior conical section  1007  such that it no longer protrudes beyond or otherwise intersects the plane in which lies the inferior surface or bottom surface of hopper tray  506 . It will be seen from an inspection of  FIGS. 29 and 30  that latch assembly  260  extends beyond or otherwise intersects the plane in which the bottom surface of hopper tray  506  lies. Thus, while bird feeder  100  may not be placed upon a flat surface for maintenance and the like (the latch assembly protruding through the plane of the bottom surface of hopper tray  506 ), bird feeder  1000 , alternatively, may be placed on a flat surface or ground plane  1002  for maintenance purposes and the like as generally depicted in  FIG. 36 . 
   It will thus be seen that hopper assembly  500  may comprise a sloped hopper partition  1007  having a superior partition surface  1008  as illustrated and referenced in  FIGS. 36 ,  37 ,  40 , and  42 – 44 ( b ); and an inferior partition surface  1009  as illustrated and referenced in  FIGS. 36 ,  37 ,  42 ,  43 , and  44 ( b ). Superior partition surface  1008  is designed to guide feed to feed outlet ports  516  (as further referenced in  FIG. 40 ) and inferior partition surface  1009  is designed to surround and cover the hopper attachment means (as preferably defined by latch assembly  260  as further referenced in  FIGS. 36 ,  37 ,  38 – 39 ( a ), and  42 – 43 ( a ), thus enabling a user to position birdfeeder  1000  upon a flat surface for maintenance purposes and the like. 
   Thirdly, inferior conical section  1007  functions to allow for the design of hopper assembly extraction means as preferably defined by a simple hopper assembly extraction tool  1010  as generally illustrated and referenced in  FIGS. 42–43(   a ). Hopper assembly extraction tool  1010  may comprise an assembly support platform  1011  as illustrated in  FIGS. 42–43(   a ); latch release means  1012  as illustrated and referenced in  FIGS. 42 and 42(   a ); and an extension portion  1013  as illustrated and referenced in  FIG. 42–43(   a ). To remove hopper assembly  500 , the latch release means  1012  is removably inserted and thus cooperatively associated with support platform  1011  adjacent the superior end of extension portion  1013 . The latch release means function to depress latch pawl  264  and thus release hopper assembly as previously described and as generally depicted in  FIGS. 42 and 42(   a ). To reinsert hopper assembly  500 , the latch release means  1012  is removed or is cooperatively disassociated with support platform  1011  and thus support platform  1011  allows latch pawl  264  to remain in an extended state for retaining hopper assembly  500  in an assembled state with bird feeder  1000  (as generally depicted in  FIGS. 43 and 43(   a ). Thus, the user may utilize the described hopper assembly extraction means to remove hopper assembly  500  from birdfeeder  1000  when birdfeeder  1000  is an elevated stated. Extension portion  1013  enables the user to reach the otherwise elevated bird feeder  1000 . As stated, the latch release means  1012  function to depress latch pawl  264 , and thereby release hopper assembly  500 . Hopper assembly  500  is then supported by assembly support platform  1011 , and the user may then bring the released hopper assembly  500  down (via extension portion  1013 ) to a more comfortable spatial orientation for maintenance purposes and the like. 
   Thus, it will be understood from an inspection of the noted figures and from a consideration of the foregoing descriptions that hopper assembly extraction tool  1010  functions to enable the user of birdfeeder  1000  to extract hopper assembly  500  from and/or insert hopper assembly  500  into birdfeeder  1000  when birdfeeder  1000  is otherwise situated above and out of the reach of the owner. 
   Modification No. 4: 
   It is further contemplated that drive assembly  300  may be modified to eliminate parts yet essentially provide the same function. In this regard, it is noted that parts removal without sacrificing function may result in the reduction of production costs and further simplifies assembly. Thus, it is contemplated that the four-bar spring assembly  320  of birdfeeder  100  may be essentially reduced by the elimination of its lower half. In this regard, it is contemplated that the non-linear closure means may be defined by a two-bar spring assembly  1020  as illustrated and referenced in  FIGS. 36 ,  37 ,  38 , and  39 . Two-bar spring assembly  1020  may comprise a medial bar  1030  as referenced in  FIGS. 38 and 39 ; a lateral bar  1031  as referenced in  FIGS. 38 and 39 ; a bar-joining junction assembly, and a superior trunnion assembly all of which operate in cooperative association with a mirror plane assembly  1040  as generally referenced in  FIGS. 36 ,  37 ,  38 , and  39 . 
   From a general inspection of  FIG. 38 , it will be noted that medial bar  1030  preferably comprises a short spacer  1324  and lateral bar  1031  preferably comprises a long spacer  1325 . Long spacer  1325  functions to space the link members  1322  of lateral bar  1031  farther apart than the spacing between the link members  1322  of medial bar  1030 . Medial and lateral bars  1030  and  1031  each comprise a superior bar end and an inferior bar end. The superior bar end of medial bar  1030  is preferably aligned with the superior bar end of lateral bar  1031  such that the superior bar end of medial bar  1030  is medial to the superior bar end of lateral bar  1031 . In other words, the spacing between the link members  1322  of medial bar is less than the spacing between the link members  1322  of lateral bar and thus medial bar may be medially aligned with respect to lateral bar. 
   It will thus be noted that medial and lateral bars  1030  and  1031  are substantially identical to medial and lateral superior bars  30  and  31  and that the superior trunnion assembly of the alternative embodiment here described is akin to superior trunnion assembly  334  and thus the superior trunnion assembly of the alternative embodiment functions to pivotally connect medial and lateral bars  1030  and  1031  at the superior bar ends. The superior trunnion assembly thus forms a superior trunnion junction. The superior trunnion assembly may comprise a trunnion ring, two trunnion pins extending laterally from the respective trunnion ring along a respective pivot axis, and a trunnion set screw. It will be understood that the trunnion ring of the superior trunnion assembly comprises a shaft-receiving aperture. The superior shaft receiving aperture is sized and shaped to receive superior shaft member  361 . It will be recalled that superior shaft member  361  preferably comprises an outer diameter that is sized and shaped to be telescopically received in the inner diameter of inferior shaft member  371 . 
   The bar-joining junction assembly of birdfeeder  1000  comprises first and second junction pins  1330  or pivot attachment means, and first and second junction springs  1332  or bar spring means as generally referenced in  FIG. 38 . Further, certain roller means for movement are cooperatively associated with the inferior bar end of lateral bar  1031  and the inferior bar end of medial bar  1030 . In this regard, it will be seen that small wheel or rollers may be mounted on a roller pin  1034  intermediate the termini of the inferior bar ends of lateral bar  1031  and medial bar  1030 . As mentioned, the roller means for movement may be defined by small wheels or rollers  1035  having pin-receiving apertures formed at the longitudinal axis thereof for receiving roller pins  1034  and having a longitudinal height lesser in magnitude than the longitudinal height of either short spacer  1324  or long spacer  1325  so as to allow free rotational movement about the wheel or roller axes. 
   It will be readily understood from an inspection of  FIGS. 38 and 39  that junction pins  1330  each comprise opposite spring-engaging ends and that they are preferably parallel to one another. In this last regard, it is important to note that junction pins  1330  have a relaxed or unactuated parallel distance as generally depicted in  FIG. 36–38 ; and a displaced or actuated parallel distance as generally depicted in  FIG. 39 . 
   First and second junction springs  1332  preferably comprise extension coil type springs and function to connect the spring-engaging ends of junction pins  1330 . From an inspection of  FIG. 38 , it will be seen that first and second junction springs  1332  essentially define the relaxed parallel distance between junction pins  1330  when junction springs  1332  are relaxed in an unextended state or equilibrium state and further define the displaced parallel distance when displaced or in an extended, non-equilibrium state. Medial and lateral bars  1030  and  1031  thus have a first angle therebetween at the superior trunnion junction. Thus, as occurs in birdfeeder  100  and illustrated in  FIG. 33 , two-bar spring assembly  1020  provides a nonlinear, geometrically-based, closure mechanism, which mechanism is driven or displaced by external load forces acting through rigid medial and lateral bars  1030  and  1031 , which mechanism is countered or restored by restorative forces in junction springs  1332  and the recovery spring  386 . 
   The junction springs  1332  produce a supportable load substantially similar to supportable load  108  as graphically represented in  FIG. 33 . Any time the supportable load  108  is greater than the applied load the two-bar mechanism or two-bar spring assembly  1020  will open or become displaced. 
   It will be further understood from an inspection of  FIGS. 36 ,  37 ,  38 , and  39  that the two rollers  1035  or wheels cooperatively engage a junction-engaging single mirror plane assembly  1040 . Mirror plane assembly  1040  is preferably circular to provide azimuthal indifference as before. Mirror plane assembly  1040  further comprises a step  1041  as illustrated and referenced in  FIGS. 37 ,  38 , and  39 . Step  1041  of mirror plane assembly  1040  is provided to preload the two-bar spring assembly  1320  so as to preclude the otherwise small displacement of shroud housing assembly  440  that occurs in birdfeeder  100  prior to unstable, full closure when the collapse load was reached. In the alternative embodiment, or birdfeeder  1000 , longitudinal translation (telescoping) of shroud housing assembly  440  occurs only when a collapse load is applied. A further feature of the two-bar assembly and mirror plane approach is that the seed holding capacity of birdfeeder  1000  may be substantially increased given the same internal operating volume. Further, filling of the hopper is less difficult for its top is more open (in view of the removal of hopper partition  522  and introduction of hopper partition  522 ( a )). 
   Modification No. 5 
   It is further contemplated that detrimental over extension of the scale spring  226  may be precluded by incorporation of a hard stop, washer  1050 . It will be recalled that the hard stop for longitudinal translation (telescoping) of shroud housing assembly  440  in birdfeeder  100  is provided by the latch assembly  260 . The latch assembly hard stop forces all loading to pass through the scale spring  226  until the load results in a taut overload cable  227 . Overload cable  227  bypasses all additional loading directly to the support member  224 . By elimination of the overload cable  227  and by the incorporation of washer  1050  as here described, it is contemplated that detrimental over extension of the scale spring  226  may be precluded more simply. Therefore, by the incorporation of washer  1050 , it is contemplated that birdfeeder  1000  may effectively reduce production costs, simplify assembly and/or disassembly, and simplify replacement of the scale spring  226  if necessary. 
   It should be noted that in the present embodiment, the longitudinal translation (stroke) of shroud housing assembly  440  is limited by a hard stop, but not by washer  1050  as referenced in  FIGS. 38–39(   a ), and  41 . The stroke is limited by recovery spring  386  reaching solid height or by inferior shaft top end  372  contacting the bottom of the superior trunnion ring, whichever method is chosen by the manufacturer. A hard stop is necessary to ensure that the drive mechanism or means does not go over center in which case the drive mechanism would be unable to perform the desired function. 
   Stretching of scale spring  226  causes superior shaft bottom end  366  to approach the aforementioned washer and would preclude full stroke of shroud housing assembly  440  if not properly accounted for. The gap between superior shaft bottom end  366  and washer  1050  is established by adding to the design stroke the stretch of scale spring  226  when the birdfeeder is at its design gross weight. In other words, when properly adjusted, the longitudinal translation (stroke) of shroud housing assembly  440  is limited exclusively by the solid height of recovery spring  386  (as a first method) or by inferior shaft top end  372  contacting the retained superior trunnion ring (as a second method). 
   The weight of all birdfeeder components (except support member  224 , washer  1050 , and flag assembly  240 ), the weight of the feed, and the weight of visiting creatures not holding onto the support member  224 , all combine to stretch scale spring  226 , for the load path is through scale spring  226  to support member  224  assuming a normal load. A consequence of this stretching of scale spring  226  is that inferior shaft member  371  slides down support member  224 . This causes superior shaft bottom end  366  to approach washer  1050 . However, superior shaft bottom end  366  will not contact washer  1050  even if telescoping has occurred provided the aforementioned combined weight does not exceed the maximum design load for scale spring  226 . 
   The maximum design load for scale spring  226  could be exceeded if a second load path were not provided. Note, that the component of the support member load that is in excess of the maximum design load for scale spring  226  can only be applied via shroud assembly  400  and would necessarily cause telescoping action, which is limited by the solid height of recovery spring  386  (assuming the first method). Therefore, the transmission path of this excess load is from shroud assembly  400  to the retained superior trunnion ring to superior shaft member  361  to washer  1050  to support member  224 , thereby bypassing scale spring  226 . The remaining support member load is transmitted via normal transmission paths which are (1) from shroud assembly  400  to the retained superior trunnion ring where it then splits between recovery spring  386  and rollers  1035  afterwhich it recombines via mirror plane assembly  1040  and continues through inferior shaft member  371  to latch assembly  260  to scale spring  226  to support member  224 ; and (2) from hopper assembly  500  to latch assembly  260  to scale spring  226  to support member  224 . Scale spring  226  could be otherwise damaged if an owner or an invader pulls abusively down on hopper assembly  500  while captured in the birdfeeder by latch assembly  260 . It should be further noted that the close fit of shroud bridge  422  and shroud body  444 , in addition to the thickness of shroud bridge  422 , contribute significantly to maintenance of alignment between shroud body  440  and hopper assembly  500 . 
   While the above description contains much specificity, this specificity should not be construed as limitations on the scope of the invention, but rather as an exemplification of the invention. For example, it is contemplated that certain parts may be eliminated in that they can be made integral with their mating parts if the structure is cast in some form of plastic. This necessarily reduces production costs and simplifies assembly and/or disassembly of the birdfeeder. For example shroud bridge  442  may be made integral with superior shaft member  361  of push rod shaft assembly  360  without comprising the function of the birdfeeder apparatus. Further, it is contemplated that the superior shaft-receiving aperture need not comprise spherical bearing  443  so as to decrease the likelihood of damage to bird feeder apparatus  100  experiencing unbalanced load forces directed against shroud assembly  400 . This damage control feature may be achieved by incorporating flexure means into push rod shaft assembly  360 . For example, it is contemplated that a rod spring may be incorporated into the superior shaft member intermediate the superior push rod shaft end  362  and the inferior push rod shaft end  366  adjacent the corrugated bridge assembly in cooperative association therewith. Unbalanced load forces directed against shroud assembly  400  would thus cause the rod spring to flex enabling bird feeder apparatus  100  to escape damage to otherwise rigid structures of bird feeder apparatus  100 . It is thus contemplated that when conjoined in action, the corrugated bridge and the self-aligning means limit critical item stresses to within the elastic range when excessive lateral or vertical loads are applied to perch assembly  460  and thus the practice of incorporating flexure means or self-aligning means into the design of an anti-squirrel bird feeder as here noted would fall within the scope and spirit of the present invention. 
   It will be further recalled that both superior trunnion assembly  34  and inferior trunnion assembly  35  preferably comprise a trunnion set screw  340  as illustrated and referenced in  FIGS. 9 and 10 . It should be noted that superior trunnion assembly  34  could be integrally formed with superior shaft member  361  and inferior trunnion assembly  35  could be integrally formed with inferior shaft member  371 . It is thus contemplated that the shaft fastening means may comprise integral connectivity between superior trunnion assembly  34  and superior shaft member  361  as well as integral connectivity between inferior trunnion assembly  35  and inferior shaft member  371 . 
   It will be further recalled that four bar spring assembly  320  preferably comprises a plurality of rigid links  322 ; a plurality of rigid spacers  324  and  325 ; a plurality of spacer screws  326 ; a plurality of spacer nuts  328 ; two rigid junction pins  330  or pivot attachment means; two four-bar springs or junction springs  332  or bar spring means; and two trunnion assemblies  334 . It is contemplated that four-bar spring assembly could be modified in any number of ways to provide a nonlinear, geometrically-based, closure mechanism (being driven by external load forces acting through the superior and inferior bars and being countered by restorative forces in the junction springs). In this regard, it is contemplated that four-bar spring assembly could be modified so as to need only four linkages, two junction springs, and a spring joining collar, which collar would have an aperture sufficiently large to move unhindered by recovery spring  368 . Further, four-bar spring assembly  320  could conceivably be modified so as to be constructed from four linkages, and two junction springs attached to the central coil of recovery spring  368  thus eliminating the requirement for a spring-joining collar. Further, it is contemplated that four-bar spring assembly  320  could conceivably be modified so as to be constructed from only four linkages and one junction spring. Thus, the junction assembly may essentially comprise pivot attachment means and bar spring means (as defined be a single junction spring), the pivot attachment means pivotally connecting two superior linkages or bars to two inferior linkages or bars and the bar spring means connecting the pivot attachment means for providing a nonlinear, geometrically-based, closure mechanism. 
   Further, hopper scale assembly  226  need not comprise scale spring  226  of an extension coil type in cooperative association with overload cable  227  as illustrated and referenced in  FIGS. 17 and 18 . It is contemplated that with a small design change a compression spring could be used in place of the described hopper scale assembly, particularly eliminating the need for overload cable  227  since a compression spring would simply reach solid, relaxed displacement if an excessive load were applied to shroud assembly  400 . In this regard, it is further contemplated that a secondary function of a compression type coil would be to maintain alignment between shroud body  444  and hopper assembly  500  should their cross sections be other than round. Further, bird feeder apparatus need not comprise a substantially circular cross section and thus diameters as herein specified may be easily modified to incorporate rectangular or triangular or any number of geometrical cross sectional configurations and thus may be defined by peripheries rather than diameters. For example, cylindrical feed-supporting surface  520  need not be cylindrical but rectangular in configuration. In this regard, it is further contemplated that a secondary function of four-bar spring assembly  320  is to maintain alignment between shroud body  444  and hopper assembly  500  should their respective cross sections be other than round. It is contemplated that bird feeder apparatus  100  of a substantially circular cross section as described hereinabove provides one of the most aesthetically pleasing constructions. The reader is reminded that aesthetics are part and parcel of the bird watcher&#39;s motivation for bird watching. 
   It is further contemplated that bird enthusiasts are often highly desirous of becoming more involved in general bird watching activities and thus may be desirous of building or constructing their own bird feeders. It is noted that actual bird feeder construction is a common activity among all types of bird enthusiasts. In this regard, it is further contemplated that the present invention may take the form of a bird feeder kit for enabling users of consumers thereof to construct a bird feeder apparatus for providing a readily available supply of feed for birds. The bird feeder kit essentially comprises the support assembly, the drive assembly, the shroud assembly, the hopper assembly, and the hopper assembly extraction means substantially as described hereinabove. 
   Thus, at its essence, the present invention discloses a bird feeder apparatus for providing a readily available supply of feed for birds, which bird feeder apparatus comprises a support assembly, a drive assembly, a shroud assembly, and a hopper assembly substantially as heretofore described. In this regard, the support assembly essentially comprises a scale assembly and hopper attachment means. The scale assembly essentially comprises a support member and scale spring means, which scale spring means function to join the support member to the hopper attachment means. 
   The drive assembly essentially comprises non-linear, geometrically-based closure means (as preferably embodied by either the four bar spring assembly or the two bar spring assembly) and a push rod shaft assembly. Notably, the push rod shaft assembly essentially comprises first and second shaft members, the first shaft member being telescopically received in the second shaft member. The non-linear, geometrically-based closure means are cooperatively associated with the first and second shaft members for telescopically operating the first and second shaft members relative to one another as earlier described. 
   The shroud assembly essentially comprises a shroud bridge and a shroud body. The shroud bridge is cooperatively associated with the shroud body adjacent the superior end thereof for supporting the shroud body and the first shaft member fixedly extends through the shroud bridge. The hopper assembly essentially comprises a hopper body, a hopper tray, a plurality of hopper partitions, and a shaft-receiving sleeve. The hopper body essentially comprises spacer-attachment means which attach the hopper tray to the hopper body in spaced relation thereto thereby defining feed outlet ports. The hopper partitions radially extend from the hopper body to the shaft-receiving sleeve and thus define a plurality of feed-receiving compartments. The hopper assembly is telescopically receivable in the shroud body; the push rod shaft assembly extends through the shaft-receiving sleeve; the support assembly extends through the push rod shaft assembly; and the hopper attachment means selectively maintain the hopper assembly in telescopic relation to the shroud body. 
   Accordingly, although the invention has been described by reference to a preferred embodiment and at least one alternative embodiment, it is not intended that the novel assembly be limited thereby, but that modifications thereof are intended to be included as falling within the broad scope and spirit of the foregoing disclosure, the following claims and the appended drawings.