Abstract:
A bird feeder is provided with a metallic perforate trough bottom that is supported on its underside on ledges consisting of a plastic material on which water tends to bead rather than sheet, and which material is essentially self-lubricating and thereby non-caking and non-sticking. In its preferred form, the bottom is a screen that is slidable horizontally on the ledges. Preferably, the material is ultra-violet ray resistant and is therefore capable of long life in the outdoors, maintaining its desired characteristics for a considerable period. The end goal is to provide easy and quick feeder cleaning capabilities, especially in sub-freezing temperatures. The design prevents moisture-absorbent wooden elements of the feeder from coming into contact with screen.

Description:
[0001]    This invention relates generally to bird feeders, and in particular to such a feeder in which the bottom of its feed-containing trough has a water pervious screen that may be removed for cleaning in sub-freezing temperatures.  
         BACKGROUND OF THE INVENTION  
         [0002]    For a number of years, the troughs of bird feeders have been provided with screens to enable drainage of rainwater or melted snow therethrough, to keep the feed dry. Prior to that, feed and shucks of seed such as sunflower would accumulate and cake, and, especially if the temperature were below freezing, would freeze into hard-to-remove clumps. Cleaning was difficult, but had to be done in order for fresh seed to move downwardly by gravity from the conventional hopper into the trough. In addition, bird excrement would sometimes accumulate with the seed residue and would place birds at risk from spread of disease. Their excrement sometimes also acted as a binding agent, effectively gluing the expended seed remains to the bottom. This made cleaning somewhat difficult, even in temperatures above freezing.  
           [0003]    Once the bird feeder industry went in fairly large measure with drainable bottom screens, liquid would pass through a perforated bottom, but the residue would still continue to pile up. Frozen clumping was not nearly as much of a problem because of water passing through the screen, but remained still. This required feeders to be removed and inverted for cleaning, until designs appeared in which the bottom screens were made to be horizontally slidable, much like the slide of a drawer. This was a valuable improvement in the art since the feeder did not then have to be removed from its post or chain. However, the manner in which the sliding bottom screen was supported, typically in grooves in the wooden sides of the trough, created a new problem when feeding birds in cold climates during winter. That is the period when bird feeding is most essential to preserve wildlife, since birds have difficulty getting food without the help of humans during winter. And if the wood from which the feeder is typically made expands from moisture at the same time seed residues tend to cake in the screen grooves and on the bottom of the trough, removing the slidable screen becomes difficult in some instances, near impossible in others. Obviously, the longer the period between cleanings of the trough because of freezing conditions, the more susceptible the birds will become to disease being spread from one bird to another and from one species to another. The need remained for enabling a screen to be removed easily and rapidly for cleaning a feeder in freezing temperatures.  
         SUMMARY OF THE INVENTION  
         [0004]    A bird feeder is provided with a metallic perforate trough bottom that is supported on its underside on ledges consisting of a plastic material on which water tends to bead rather than sheet, and which plastic material is essentially self-lubricating and thereby non-caking and non-sticking. Preferably, the material is also ultra-violet ray resistant and is therefore capable of long life in the outdoors, maintaining its other desired characteristics for a considerable period. The end goal is to provide easy and quick feeder cleaning capabilities, especially in sub-freezing temperatures.  
           [0005]    A principal object of the invention is to provide a bottom screen for a bird feeder trough, which screen is supported in a manner making it capable of easy and quick removal and reinstallation, particularly in freezing temperatures.  
           [0006]    A further object is to provide a removable metal screen at the bottom of a bird feeder trough, and to support that screen solely on plastic ledges having a slick surface on which water only tends to bead.  
           [0007]    An ancillary object is to support such a metal screen in a manner that it does not come into contact with moisture absorbent wooden portions of the structure.  
           [0008]    More specifically, an object is to provide ledges for the screen, which ledges are made from a plastic material that is impervious to water, and which ledges have self-lubricating and non-caking characteristics.  
           [0009]    Still more specifically, an object is to provide ledges that are made of an ultra-high molecular weight polyethylene that is preferably resistant to the rays of ultra-violet light.  
           [0010]    Other objects will become apparent from the following description, in which reference is made to the accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]    [0011]FIG. 1 is an isometric exploded view of a bird feeder trough that may be part of either an off-the-ground or ground feeder.  
         [0012]    [0012]FIG. 2 is a fragmentary view taken along lines  2 - 2  of FIG. 1, illustrating the trough in cross-section taken essentially along lines  2 - 2  of FIG. 1, as part of a hopper-type feeder which may be either suspended from chains or supported on a pole.  
         [0013]    [0013]FIG. 3 is a fragmentary cross-sectional view taken along lines  3 - 3  of FIG. 1.  
         [0014]    [0014]FIG. 4 is a fragmentary cross-sectional view taken along lines  4 - 4  of FIG. 1.  
         [0015]    [0015]FIGS. 5 and 6 are top and side views respectively of a ground-type feeder incorporating the novel screen supports, but enabling its removal by either inverting the trough or lifting the screen from below.  
         [0016]    FIGS.  7 - 12  illustrate several alternative designs of ledges for supporting the screen. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0017]    [0017]FIG. 1 illustrates a trough  10  and a metal screen  12  that is slidable horizontally in opposite directions as indicated by the arrow  14  between a seed-supporting position within the confines of the trough  10  and a remote position shown in full lines at the exterior of the trough. When within the trough, the screen  12  will support seeds between the inner vertical surfaces of side walls  16  and  18  and end walls  20  and  22 . The terms side walls and end walls are used herein for convenience of description and claiming, it being understood that all four walls should be considered side walls, whether extending along the length or width of a rectangular or square trough. The tops of the side walls typically present a perch for birds to stand during feeding, but smaller birds frequently stand directly on the feed and feed residues lying in the trough. The screen  12  has a pattern of holes which are suitable for adequate draining of water or melted snow, and the holes will be of dimensions enabling whatever kind of feed that is being supplied to keep from passing through the screen. While I prefer using a heavy gauge aluminum screen to provide sufficient rigidity to support both seed and birds, any kind of screen can be used, including plastic, expanded metal, etc. The particular screen I find useful is approximately {fraction (1/16)} th  of an inch thick, has {fraction (1/16)} th  of an inch diameter holes and has spacing between holes of approximately ⅛ th  of an inch. Any configuration and size of openings may be used according to the feed material offered to the birds or other animals.  
         [0018]    A key feature of my invention relates to the manner in which I support the screen  12  within the trough  10  so that the screen can become effectively non-sticking when it comes to its having to be removed for cleaning during freezing temperatures. To achieve this end, I provide special material ledges  24  and  26  on which the screen  12  rests when in seed-supporting position within the trough  10 . Those ledges are preferably a high molecular weight polyethylene of the type designated UHMW-PE produced by Crown Plastics of Harrison, Ohio. The material is said by its manufacturer to have characteristics of outstanding impact strength at even very low temperatures, a low coefficient of friction, self-lubricating capabilities (non-caking and sticking) and is FDA and USDA approved. In addition, it is capable of being produced in ultra-violet light resistant form, extending its life in the outdoors for a considerable period. It also has stress cracking resistance, making it useful in the narrow strip form illustrated for the ledges  24  and  26 . It has a molecular weight average ten times that of conventional high density polyethylene resins.  
         [0019]    In FIG. 2, I illustrate the trough  10  and screen  12  being used in conjunction with a superstructure  28  in the form of wooden ends  30  (only one of which is shown) and a pair of transparent hopper sides  32  which conventionally are vertically insertable from above into grooves formed in the wooden ends  30 . The ends  30  and sides  32  form a hopper for containing seed therebetween. Since the hopper, the manner of placing the feed into the hopper and the manner of either suspending the feeder from chains or mounting it on a post are not a part of the novel aspect of my preferred form of the invention of FIGS.  1 - 4 , let it suffice to say they can be any of several different structural designs.  
         [0020]    The side and ends walls  16 ,  18 ,  20  and  22  and the ends  30  of the hopper are all constructed of appropriate exterior-type wood, ideally being cedar for its well-known long life characteristic. The manner in which the separate wooden elements may be interconnected is preferably through use of rust-resistant screws at points  34 , but the fasteners may be of any suitable type provided they form a firm feeder structure. As seen in FIG. 1, the side walls  16  and  18  are grooved with a saw kerf for their full lengths to receive the strip ledges  24  and  26 . The inner edges of the ledges may extend inwardly of the inner surfaces of the side walls approximately ¼ th  of an inch to support the screen  12 . Once in place, the ledges, which are only ⅛ th  of an inch in thickness, may be easily stapled upwardly from the undersides at an angle in one or more locations where the ledges enter the grooves. Depending on the size of the feeder, two-side edge support of the screen may be sufficient by itself. If however, the trough is of such large horizontal dimensions that additional screen support is desired, the screen can either be made of thicker material or additional ledges can be provided for the screen at one or both of the end walls  20  and  22 . For example, end wall  22  may be grooved similarly to side walls  16  and  18  and an additional ledge provided between the inner edges of ledges  24  and  26  as seen in FIG. 2.  
         [0021]    Cross-referring to both FIGS. 2 and 3, it will be seen that the lower inner side of end wall  22  is notched inwardly at  36 . This allows both the screen  12  and ledge  26  to extend somewhat into the notch and prevent seed from escaping at that location. Obviously, if an additional ledge were provided in end wall  22 , the notch  36  would not be necessary.  
         [0022]    In FIG. 4, the screen  12  is resting on the ledges  24  and  26  and is shown as having a depending lip  38  that is preferably integral with the screen  12  by being bent downwardly therefrom. The lip  38  contacts the rightward ends of the ledges  24  and  26  when the screen  12  is filly inserted as shown in both FIGS. 3 and 4. Immediately above the lip  38 , a strip  39  of the UHMW-PE material may also be stapled to the underside of end wall  20  to assist guiding the screen  12  into place when being returned to the trough after cleaning. To enhance the guiding, the lower outside corner of the strip  39  may be beveled or rounded off. The strip  39  also prevents moisture absorbed by the wooden end wall  20  from coming into contact with the top surface of the screen and causing sticking in cold weather. A retaining latch  40 , shown only in FIG. 1, can be moved from a non-retaining position shown in solid lines in FIG. 1 by pivoting it about a screw to cause it to extend downwardly and prevent the screen lip and screen from moving to the right in FIG. 4 once it has been installed.  
         [0023]    [0023]FIGS. 5 and 6 illustrate another type of feeder which can stand on legs  42  directly on the ground or some other flat surface. Alternatively, the feeder of FIGS. 5 and 6 may be mounted on a tree or suspended at its corners from chains. With such a feeder, slidability of the screen  12 ′ as illustrated in the preferred form of the invention is unnecessary, since there is no superstructure such as a hopper above the trough. For cleaning the trough, the feeder may simply be turned over to remove the screen and residue, or the screen can be pushed upwardly from below. For this reason, at least two opposing side walls of the trough should be grooved for reception of ledges similar to those in the earlier embodiment. Or, in anticipation of heavier wildlife such as squirrels also feeding from the trough, ledges can be provided on all four walls of the trough  10 ′ as shown in these Figures. As a result of the fact that the ledges are made of a plastic material on which water only beads instead of sheets, the screen  12 ′ prime is easily and quickly removable for cleaning during freezing temperatures.  
         [0024]    FIGS.  7 - 12  illustrate the very many different designs that are possible, including others not depicted here. In FIG. 7, the ledge  26   a  may be inset into a groove in the wooden side wall  18   a , with the ledge itself being grooved to receive the screen  12   a . Ledges  26   a , as is also true of several of the following ledges about to be described, are secured in the grooves in one manner or another. Stapling, as illustrated at  44  in FIGS.  810  may also be used to secure any of the ledges in their grooves. In FIG. 8, ledge  26   b  may be stapled to the underside of the ledge  18   b . FIG. 9 is quite similar to FIG. 8 except that the ledge  26   c  is attached to the inner vertical surface  46  of its side wall. FIG. 10 shows screen support similar to FIG. 9, except that the ledge  26   d  is inset in a notch in the side wall. FIG. 11 is somewhat like the arrangement of FIG. 7, but the ledge  26   e  is in the form of a flat rather than a grooved strip. FIG. 12, although not readily practical under present pricing structure for the UHMW material, illustrates that the side walls themselves can be constructed of the non-stick material, with the ledges being formed by merely grooving the side walls.  
         [0025]    The size of the feeder and thus the trough may be of any suitable dimensions for such feeders, keeping in mind that the stiffness of the screen and the number and dimensions of the ledges on which the screen is supported should be selected in accordance with the type of birds or other wildlife normally expected to seek food at the particular feeder. The grooves which receive the ledges can be made to receive them snuggly, since expansion of the wood in which the grooves are made is of no significance, such as it would be if the grooves actually supported the edges of the screen as in prior art designs. There is little chance of any contact of any of the wooden elements of the trough or other parts of the feeder with the metal screen; consequently, freezing moisture has little opportunity to cause sticking of the screen to its support. The screen  12  it totally and completely supported on the UHMW-PE material in the FIGS.  1 - 4  embodiment. It can be noted that there is some slight clearance between the outer edges of the screen  12 ′ relative to the inner surfaces of the side and end walls of the ground feeder of FIGS.  5 - 6  to avoid ice formation on wet wood from inhibiting removal of the screen  12 ′. Caking of feed residue, snow and ice can gather around the edges of the screen  12 ′, but since there is no sliding action required for the screen as in the preferred embodiment, removal is not that difficult.  
         [0026]    Various other changes may be made in the details of the design without departing from the spirit and scope of the claims.