NZ270011A - Animal control substance dispenser: poison added to fliud attractant only when animal detected - Google Patents

Description

PATENTS FORM NO. 5 Fee No. 4: $260.00 PATENTS ACT 1953 COMPLETE SPECIFICATION After Provisional & 1,3 ' f /« ^ No: 270011 V t\\ Dated: 28 April 1995 14 AUG J99Q ^ James & Wells Ref: 10710/14 LR PEST CONTROL We The Horticulture and Food Research Institute of New Zealand Limited of Batchelor Centre, a New Zealand company of Tennant Drive, Palmerston North, New Zealand hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed to be particularly described in and by the following statement: 1 * Q ^ r, PEST CONTROL Technical Field This invention related to pest control.

Although the present invention can be used in respect of various pests 5 including rats, goats, deer and insects, for ease of reference the target pest shall be referred to as possums (Trichosuros vulpecula).

It should be appreciated that the general principle of most pest control devices or methods is to limit or control the pest population.

The description of the present invention generally refers to a control 10 action preferably the dispensing of a poison. It is also envisaged that other substances could be dispensed, which might for example cause the pest to ingest a substance which modifies their reproductive physiology or behaviour, or modifies the effectiveness of their immune system, or induces a disease, or induces a parasitic infection. Alternatively, the 15 substance may vaccinate the animal against a disease. background art The predominant population control methods used in New Zealand at present involve the distribution of poisoned baits, by air or in feeders known as bait stations. These methods have limited effectiveness for 20 several reasons.

Firstly, many poisons can be detected by the animal unless they are present in the bait in very low concentrations. It is difficult to prevent some trace of the scent of the poison from diffusing throughout the bait, particularly 2 0 0 11 since the baits, as a matter of practical necessity, have to be manufactured some time before use. Masking scents are usually incorporated in the bait but are not completely successful. A consequence of the low concentration of poison is that a large amount of bait has to be 5 consumed for the animal to ingest a lethal dose of poison. Thus often inadequate amounts of bait are ingested, and the animal becomes ill from a sub-lethal dose. After recovery, the animal often will develop a strong aversion to baits. In practice this can occur in a substantial proportion of the animal population, and control becomes inadequate.

Secondly, the baits do not last a long time in the field. Since the animal has to ingest a large amount of bait, for the reasons given above, the baits need to be foodstuffs, and they are prone to decay after a few weeks or months in forest conditions. In practice it appears that there is a substantial proportion of animals that do not take the bait within the 15 effective lifetime of the bait.

To ensure that the animals will take the bait within that short lifetime, animals are often fed with similar but unpoisoned baits for a few weeks prior to the distribution of the poisoned baits, This is commonly called pre-feeding. By this means when poisoned bait is finally supplied, the 20 animals will be incautious, will accept it rapidly, and will usually take in a fatal dose. Unfortunately, pre-feeding generally has to be done by means of a separate visit to the region, thus considerably increasing the already-high costs of the poisoning operation.

Thirdly, another problem with bait stations is that individual animals 25 often consume much more bait than is required for a fatal dose before succumbing to the effects of the poison. As a result a substantial quantity of poison may be wasted. 3 27 § 0 11 Because the costs of conventional poisoning operations are high, the operations can only be repeated every few years, by which time the pest population density may rise to serious levels again.

It can be seen that it would be desirable to have a pest control device or 5 method of pest control that is efficient and works effectively.

It is an object of the present invention to address the foregoing problems or at least to provide the public with a useful choice.

Further aspects and advantages of the present invention will become apparent from the ensuing description which is given by way of example 10 only. disclosure of invention According to one aspect of the present invention there is provided a method of applying a control action to an animal characterised, by the steps of a) first introducing the animal to a carrier substance, and then b) applying the control action wherein the applying of the control action is initiated by the presence of the animal, and wherein the control action is the addition of an active substance within the carrier substance.

In preferred embodiments of the present invention the carrier substance is a substance to which the animal is attracted.

In some preferred embodiments the carrier substance is a food.

The active substance may now conveniently be thought of as being poison. 4 27 0 0 1 1 However it should be appreciated that the active substance may have some other function for example modifying the animals reproductive physiology or behaviour, modifying the effectiveness of the immune system or may induce a disease or a parasitic infection. In alternative 5 uses of the present invention the active substance may be a vaccine , a vital trace element or have some other therapeutic effect. It should therefore be appreciated that the latter uses of the present invention will be not be necessarily used in respect of pests (although possums could be inoculated against tuberculosis) but in respect of saving endangered 10 species.

The carrier substance and the active substance may come in a variety of forms, for example solids, granules or even gas.

However, in preferred embodiments of the present invention both the carrier substances and the active substances are fluids which can 15 include particulate material.

In further preferred embodiments the carrier substance and active substances may be: i) oils, ii) aqueous solutions, or iii) other solutions which are not oils or aqueous solutions, such as alcohols for instance.

Provided that carrier substance should not be substantially miscible with the active substance. The advantage these embodiments have is that the active substance will not be able to significantly dissolve in the carrier 25 and thus contaminate it. 17 8 0 1 1 The applicant has found it advantageous to dispense the active substance within the carrier substance once the animal has been detected. The advantage of dispensing the active substance by this means is that the surrounding carrier substance can prevent the animal detecting the 5 poison and therefore stop learned aversion from occurring. Furthermore, surrounding the active substance (once dispensed) with carrier substance enables concentrated poisons to be used as these will not be detected by the animal due to the presence of the surrounding layer of carrier substance.

According to another aspect of the present invention there is provided a dispenser of a fluid medium characterised in that the dispenser can be positioned above ground in such a manner that the fluid medium can exit the dispenser and under gravity form a fluid trail along a surface inclined away from the horizontal with respect to the dispenser.

In some embodiments the dispenser instead of dispensing the fluid medium to form a trail may dispense the fluid medium so as to form a pool of fluid medium.

Throughout the specification reference will be made to the present invention as being a dispenser as described above which dispenses both a 20 carrier substance and an active substance in fluid form according to the method described previously. It should be appreciated however that the dispenser and the method of control action can be utilised separately from each other in appropriate circumstances.

If the present invention is used with respect to possums, it is envisaged 25 that the surface on which a fluid trail is dispensed by the dispenser would be a tree. The surface will now be referred to as a tree throughout the 6 specification, again however it should be appreciated that the present invention could be used with other surfaces, such as fence posts, ramps and so forth.

The applicant has found that suitable carrier substances for use with possums are sweet syrups such as molasses or nut flavoured oils. These can be easily dispensed as a liquid.

In other embodiments, the carrier substance may be a non-food substance which may be more resistant to degradation.

No matter what the carrier substance is, it may include additives such as flavouring, scents or sweeteners which are particularly attractive to the target animal. Viscosity modifiers may also be included to reduce flow-rate variation. Biocides and antioxidants may also be included to increase the life of the carrier substance.

In some embodiments, in addition to being attractive to the possum, it is important that the carrier substance has properties which lend itself to forming a trail which animals can locate at a point some distance away from the dispenser. This ensures that the animal can locate the fluid trail of the carrier substance while being far enough away from the dispenser so that the dispenser induces little fear in the animal. For animals such as possums, the carrier substance will preferably form a trail which is sufficiently bulky that the possum will regard it as a valuable food source. With other animals, the trail may need to be no more than a trace of a scent. In either case the desired outcome is that the animal's normal inhibitions about approaching the dispenser will be overcome by the intensity of the rewards it experiences as it follows the trail. > l£= 7 0 0 It Molasses does form a sufficiently bulky trail which is not substantially absorbed by the tree and which is readily visible to a foraging possum.

If the carrier substance is of insufficient thickness to provide a bulky fluid trail which is not absorbed by the tree, then its viscosity may be 5 altered by an additive. Suitable additives may include cornflour, carboxymethylcellulose or an oil. In some embodiments the additives may react with the air and to some degree solidify thus forming a thick stream resembling that formed by the exudation of resin from the tree.

The visibility of the fluid trail may be enhanced also by colouring the 10 carrier substance or attaching materials such as a reflective or coloured tape close to the fluid stream of carrier substance. In some embodiments the fluid may flow down the tape, which can help prevent absorption of the carrier substance into the tree.

One problem with continuously-dispensed syrups as baits might be that 15 wasps, bees and ants will remove the syrup and reduce its availability to the target animal. One possible way of discouraging insects is the incorporation of isovaleric acid in the syrup. This appears to repel insects but not possums. It has been shown to be effective in pellet baits, but its strong smell (rancid cheese) has so far made it unacceptable to field 20 workers. The smell would not be an issue with a dispenser as proposed.

An alternative way to minimise wastage of the syrup would be to incorporate a device which will cause the syrup to be dispensed only at night, when the target animal may be particularly active.

In some embodiments in addition to there being an attractive carrier 25 substance there may be provided some other kind of lure for attracting the animal to the dispenser. 8 27 0 0 1 f For instance, in some of the embodiments the lure may be some form of light or other object which the target animal finds attractive.

In other of these embodiments the lure may be created by a sound generating device or by a scented substance. For instance, in some 5 embodiments a suitable lure may be a vegetable oil containing an attractive fragrance, for example peanut scented vegetable oil. It should be appreciated in some embodiments the lure may be the same substance as the carrier substance.

One advantage of having an additional lure is that this may be used to 10 attract animals with a poor sense of smell, or in situations where the use of scented attractants is not feasible.

The dispenser may come in a variety of forms. In preferred embodiments the dispenser may have at least one substantially impermeable container. In further preferred embodiments, the dispenser may be a collapsible, 15 substantially impermeable container, for example a bag which contains a fluid. This in preferred embodiments does not allow the entry of air, moisture or micro-organisms which may degrade either the carrier substance or the active substance.

The rate of fluid flow of carrier substance and/or scented lure from the 20 dispenser may be determined by gravity, air or gas pressure, and by selection of a suitable nozzle or flow control mechanism. Preferably the fluid flow rate is low enough that the fluid lasts for a considerable period of time, yet there is enough fluid dispensed to attract the animal.

It should be appreciated that if a nozzle is used, the entry of micro-25 organisms into the dispenser is likely to be avoided because in general micro-organisms are unlikely to be able to grow through the fluid faster 9 than the fluid flows out.

In preferred embodiments, although the flow rate of fluid under gravity provides a simple fluid dispensing mechanism, under some circumstances it may be desirable to dispense the fluid with a more 5 positive or more controlled rate of flow. This may be done to reduce consumption of fluid by dispensing it only when the target animals are active, or it may be to overcome undesirable variations in flow due to viscosity changes in the fluid. Viscosity changes could be related to ambient temperature or to changes in the fluid properties with time, for 10 example by crystallisation.

In one embodiment of the dispenser, the pumping mechanism will utilise the slow expansion of a material due to contact with the air. This contact will preferably be initiated at the time the device is deployed in the field, for example by opening a previously sealed aperture and allowing 15 surrounding air to contact the material. The material may for example be a substance which swells upon absorbing moisture. The rate of swelling may be controlled by restricting access of surrounding air to the material, for example by allowing air entry only through a semipermeable membrane, or through one or more small holes, in either case 20 limiting the rate at which moisture is transferred to the material.

If the swelling material and the flexible container of fluid are together contained within another container which is substantially rigid, the expansion of the swelling material will displace the fluid.

The effectiveness of the invention does not depend on a constant rate of 25 flow, only on having flow occur over a long period. Thus it does not matter if the rate of fluid dispensation is irregular. The average rate 27 0 0 1 1 should be predictable within acceptable margins (i.e. ± 50%), for example by calculation from average atmospheric humidity.

The specifications of the rate-limiting means may be selected to suit the devices to the climate they are to be exposed to. For example, swelling 5 material in a device which is to be deployed in a very humid area might be surrounded by a plastic membrane with a relatively low permeability to moisture.

Other swelling mechanisms may be used, for example swelling of a solid upon oxidation, or an evolution of gas from chemicals, or slow release of 10 gas from a container in which gas is stored under pressure. The slow release in the latter case may be controlled by the permeability of a material which blocks some part of the flow path, for example a sintered ceramic.

In an alternative embodiment, the pumping mechanism may be powered 15 by utilising fluctuations in temperature or barometric pressure. Temperature changes can be converted to mechanical movement through such a device as a bi-metallic strip. Pressure changes can be similarly converted by such a device as a sealed bellows. In either case the small movements can be converted to a unidirectional movement by a 20 ratcheting mechanism.

In one example, a roughened or serrated rod is clamped by two sets of jaws. The jaws have bevelled edges set such that the rod will slide downwards through them, but upwards movement of the rod is prevented by interference between the jaws and the rod surface. One set of jaws is 25 attached to a source of movement, which in this example is a sealed bellows which will expand and contract in response to both temperature 11 ? and pressure changes. When the bellows expands, the moving set of jaws will bite into the rod and push it downwards, and the rod will slide through the stationary set of jaws. When the bellows contract, the stationary jaws will prevent downwards motion of the rod, and the 5 moving jaws will slide along the rod. Repetition of this cycle will result in a creeping unidirectional motion of the rod. This motion can be used to compress a flexible container of fluid, thereby causing some of the fluid to be dispensed through an opening in the container.

In another embodiment, the pumping mechanism may be powered by 10 electrical or electromagnetic means, for example by the discharge of a battery through an electric motor or clock mechanism.

In another embodiment, the pumping mechanism may be driven by the action of a vane which is moved by the wind, perhaps through a unidirectional mechanism as described above. If the vane is light-15 coloured, its movement is likely to have an additional attractive effect on some animals, for example possums.

In all preferred embodiments the active substance is dispensed from the dispenser only when the animal is detected consuming the carrier substance. By this means the active substance will almost always be 20 completely consumed by the target animal. Thus the active substance will not be available in the general environment as it would be if, for example the carrier substance itself contained the active substance.

The means by which the presence of the animals can detected so as to introduce the active substance to the carrier substance may vary. In 25 some embodiments, the animal may be detected by a sensor such as an optical, infra-red, or capacitive sensor and the like. In other 12 27 0 0 1 1 embodiments, the animal may be detected by the presence of its weight on a platform or lever.

However, in preferred embodiments the animal is detected by the animal pushing on a barrier which restricts its access to the last drip on the dispenser nozzle. It should be noted that a common action for possums is to push ahead with their nose and therefore this method of activation is very suitable for use with possums.

In one embodiment, the barrier may push against a pump or nozzle which allows the active substance to emerge from the dispenser in combination with the carrier substance.

In preferred embodiments, the dispenser will include a timing device, which will delay the resetting of the dispenser. The delay should be a long enough period (i.e. at least greater than a minute) to ensure that an individual animal does not consume multiple doses of the active substance, which would be wasteful.

In some preferred embodiments the masking of the active substance by the carrier substance is enhanced, by arranging the mechanism so that carrier substance is dispensed before the active substance is dispensed. The carrier substance may also be dispensed after the active substance has ceased to be dispensed. The advantage of this is that it helps ensure that when the animal has consumed the mixture of carrier and active substances, no remnants of active substance, for example poison are left exposed. This is important as such exposure of active substance could allow subsequent animals to detect the active substance.

In preferred embodiments the above object is achieved by means of a peristaltic pump for dispensing the carrier and active substances. The 13 peristaltic pump dispenses carrier substance for a longer period of time, than that in which the active substance is dispensed.

It can be seen in the present invention may offer a number of advantages over the prior art.

The present invention offers an alternative to previous expensive pre-feeding operations by providing a slowly dispensed fluid bait.

Yet, the present invention has the advantage of pre-feeding as the long trail of fluid (without the active substance added) encourages the animal to approach the dispenser and lose its inhibitions in doing so. It is only 10 when the animal is at the dispenser that the active substance is administered in an appropriately large dose so as to kill the animal.

The present invention is also environmentally sound in that the substance which does flow down the tree contains no significant quantity of active substance - such as poison, this avoiding accidental poisoning of 15 humans and non-target wildlife.

Another advantage is that an active substance - such as poison is only introduced to the carrier substance when the animal's presence is sensed and therefore there is very little active substance wastage. This allows sophisticated and expensive active substances to be used in a cost effective 20 manner. Furthermore, addition of the active substance only once the animal's presence is detected ensures there is not enough time for the scent of the active substance to diffuse, with the result that the scent of the active substance is masked by the carrier substance.

Yet another advantage of the present invention is that it can be tailored to 25 target animals, either by the choice of the carrier substance or lure 14 27 0 0 1 1 utilised or by the manner in which the presence of the target animal is detected.

A further advantage is that by dispensing of carrier substance before and immediately after the active substance has been dispensed this ensures 5 there is no residue of active substance left which subsequent animals may be able to detect.

If the fluids are kept in a container from which air is excluded, the fluid is less likely to deteriorate or solidify.

Brief Description of Drawings Further aspects of the present invention will become apparent from the ensuing description which is given by way of example only and with reference to the accompanying drawings in which: Figure 1 is a diagrammatic view of a dispenser in accordance with 15 one embodiment of the present invention; Figure 2 is a diagrammatic view a means of dispensing fluid in accordance with another embodiment of the present invention, and Figure 3 is a diagrammatic view of a dispenser in accordance with a 20 further embodiment of the present invention, and Figure 4 is an enlarged perspective view of part of the peristaltic pump shown in Figure 3.

Best Modes for Carrying out the Invention 700111 With respect to Figure 1, there is provided a dispenser generally indicated by arrow 1 which is mounted by a mounting lug generally indicated by arrow 2 to a tree 3.

The dispenser 1 has a housing 4 inside of which is a container 5 which 5 contains syrup 6 and a container 7 which contains poison 7a.

Container 5 is collapsible and dispenses under gravity the syrup 6 through the dispenser nozzle 8.

Situated close to the nozzle 8 is a barrier arm 9 pivotable about a pivot 10.

Upon pivoting, the barrier arm 9 contacts an actuator arm 11 which in 10 turn operates a pump 12 on the poison container 7. This causes the poison 7a to pass through tubing 13 to be dispensed out to the nozzle 8 along with the syrup.

In preferred embodiments, the actuator arm 11 requires a force to operate it that can only be provided by large animals such as a possum pushing 15 with its nose in an attempt to reach the syrup source, thus ensuring the target specificity of the dispenser 1.

With reference to Figure 2, there is illustrated an alternate means of dispensing fluid to that illustrated in Figure 1.

In this embodiment, a roughened or serrated rod 19 is clamped by 20 stationary jaws 20 and moveable jaws 21.

The jaws 20 and 21 have bevelled edges set such that the rod 19 can slide downwards through the jaws but is prevented from moving upwards by interference between the jaws 20 and 21 and the surface of the rod 19.

The moveable jaws 21 are connected to a bellows 22 which expand and 16 27 0 0 1 1 contract in response to both temperature and pressure changes.

When the bellows 22 expand, the jaws 21 bite into the rod 19 and push the rod 19 downwards. The stationary jaws 20 allow the rod to slide there through.

When the bellows 22 contract, the stationary jaws 20 prevent downwards motion of the rod 19 allowing the moveable jaws 21 to move upwards along the rod.

Repetition of the cycle will result in creeping unidirectional motion of the rod. This motion can be used to compress a flexible container of fluid such as container 5 illustrated in 1 thereby causing some of the fluid to be dispensed through an opening in the container 5.

With reference to Figure 3 there is provided a dispenser generally indicated by arrow 30 which is mounted by a mounting lug 31 to a tree 32.

An animal is attracted to the device by means of a lure which may be in the form of a visually attractive object x or a sound generating device (not shown). In the embodiment illustrated the lure is in the form of an attractive scent (not shown) which is stored and dispensed from a container 33.

The scented lure may be dispensed either as a vapour (not shown) or alternately as a viscous fluid (not shown). The lure is dispensed via a tube 33a so as to run down a platform 34 and further down the tree 32, thereby laying a trail which will encourage even shy or neophobic animals to approach the dispenser 30.

To prevent deterioration of the lure so that it is available for a period of several years, the lure container 33 is substantially impermeable to air. 17 The lure container 33 is also made from a flexible material such that discharge of the lure is accommodated by the gradual collapse of the container 33 rather than by the ingress of air as would be the case with a rigid container.

To achieve a slow rate of discharge, in order to make a practically sized volume of lure last several years, discharge is restricted by means of a porous plug 35.

Other means for providing a slow rate of discharge are also envisaged (not shown), for example controlling the rate of discharge by using an 10 electrical timer, or by using a valve activated by daily temperature fluctuations.

The dispenser 30 also has a container 36 which contains a scented carrier substance (not shown) in fluid form. It should be appreciated that the scent of the carrier substance may or may not be the same as that used in 15 the lure.

The carrier substance when discharged is ultimately conveyed to a nozzle 37 via a tube 38. The tube 38 is preferably constructed of a thin-walled flexible material, for example silicon. Flow of the carrier substance is prevented by a spring-loaded clamp 39, except when the closing force of 20 the clamp 39 is overcome by pressure generated by the three channel pump generally indicated by arrow 40.

The dispenser 30 also has a container 41 which contains an active substance now referred to as poison (not shown) in a fluid form. Container 41 is connected via a tube 42 to an inner nozzle 43 located 25 within nozzle 37.

IS 27 0 0 1 1 Tube 42 is made of similar material to tube 38. The flow of poison is also prevented by a spring-loaded clamp 44 except when the closing force of the clamp 44 is overcome by pressure generated by the pump 40.

In the embodiment shown containers 36 and 41 are similar in 5 construction and function to container 33, that is they substantially protect their contents from contact with the air and collapse to allow discharge of their contents without ingress of air.

When an animal approaches a device it will seek the source of the attractant (i.e. lure or carrier substance or both) within the dispenser 30. 10 However, access to the source of the attractant, which is nozzle 37 is obstructed by a barrier arm 45. The gap 46 between the barrier arm 45 and the platform 34 is large enough to ensure that the animal is aware of where the attractant source is located. The gap 46 is however too small and too far away from the nozzle 37 for the animal to be able to reach the 15 attractant source, for example by using its tongue.

In its efforts to approach the attractant (i.e. lure and/or carrier substance), the animal will push against barrier arm 45. The sides of the dispenser's housing (not shown) and platform 34 are designed to allow the animal a good purchase for its claws on the tree 32 or on the platform 20 34, so that it can exert a considerable force on the barrier arm 45.

Barrier arm 45 is hinged at a pivot 47 and normally held in a closed position by a spring 48.

It should be appreciated that the resistance of the spring should be such that the animal's efforts will be sufficient to allow the barrier arm 45 to 25 open in response to the animal's efforts to reach the attractant source. 19 Tn 011 As the barrier arm 45 opens it carries with it a roller 49 which is attached to an arm 50. After the barrier arm 45 has opened a few millimetres, roller 49 comes in contact with tubes 38, 42 and 51 which are all in contact with a fixed plate 52.

The shape of the plate 52 is made more apparent in Figure 4 which is discussed below.

When the barrier arm 45 opens further as indicated by the dashed lines, roller 49 compresses tubes 38, 42 and 51 against plate 52 to the extent that the tubes are fully occluded. The motion of the roller 49 hence generates a 10 pressure which can force fluid along each of the three tubes 38, 42 and 51 in the manner of a multi-channelled peristaltic pump. The reliability of the pumping action may be enhanced by having at least a slight resilience in the arm 50.

The detailed action of the pump 40 is best understood with reference to 15 both Figure 3 and Figure 4. Tubes 38, 42 and 51 lie along the longer section 100 of the plate 52. Tube 42 lies along the shorter section 101 of the plate 52. Compression of the tube 38 (containing the carrier substance) therefore occurs before compression of tube 42 (containing the poison) and also continues for a longer period of time.

The effect of this is to extrude at nozzle 37 a quantum of carrier substance followed by a further quantum of carrier substance with poison at its centre, further followed by another quantum of carrier substance without poison. If the sizes of the quanta and the diameter of nozzles 37 and 43 along with the viscosities of the carrier substance and poison are all 25 chosen correctly, a single drop will emerge from nozzle 37 consisting of poison surrounded by a carrier substance. 27 0 0 1 1 The drop will preferably hang from nozzle 37, but in some alternative embodiments may fall into a cup or onto a surface.

In other embodiments the drop may be created on a cup or on a surface.

It should be appreciated that what embodiment is chosen will depend on 5 the behaviour of the target animal.

Whilst the roller 49 is traversing plate 52, the gap 46 is still too narrow to allow the target animal to reach the nozzle 37.

The target animal will not be able to reach the nozzle 37 until the roller 49 has travelled substantially past the end of plate 52.

Spring 48 is strong enough that very small animals which could otherwise get through the gap at this stage, will be unable to overcome the spring force.

By this means all animals, if they get access to the nozzle 37 at all, will be presented with a full dose of poison. Thus, the presentation of sub-lethal 15 doses (which can lead to learned avoidance of baits and poisons) will be avoided.

When the animal gets access to nozzle 37, it will lick the drop. As the drop is small compared, with the animal's tongue the whole drop will enter the animals mouth at once.

It is believed there is little likelihood of the animal detecting the presence of the poison for several reasons: a) the poison has only been inserted into the drop of carrier substance a matter of seconds previously, such that there should not be sufficient time for there to be diffusion of the poison scent to the 21 27 9 0 11 surface of the drop; b) the arrangement by which the poison is followed by a quantum of carrier ensures that there will be no residue of poison left over from the previous occasion that the device was activated (i.e. to contaminate the carrier substance); c) the carrier substance is scented and very attractive to the animal; d) in preferred embodiments the carrier is an oil and the poison a hydrophilic compound in an aqueous solution or suspension. Thus, the poison will not be able to significantly dissolve in the carrier substance and contaminate it, in the period prior to the animal's ingestion.

After the animal has taken the drop into its mouth some poisons will cause rapid distress such that the animal will withdraw and not return.

However, many useful poisons do not cause immediate distress and if 15 steps are not taken to prevent it, the animal could discover that by withdrawing and re-entering the device, it can dispense another drop of carrier substance.

This could result in substantial wastage of carrier substance and poison before the animal eventually succumbs to the ill-effects of the poison.

In order to avoid this situation, tube 51 acts a timing device which prevents reactivation of the pump 40 for a sufficient period that the animal will in most cases become disinterested and abandon the device after receiving only a single dose of poison.

A possible advantage of this is that with some animals, for instance 25 possums, it is believed that an animal which has found a food source will mark the area and thereby attract other target animals to the same site. 22 The timing device created by tube 51 works as follows.

As the animal is pushing open the barrier arm 45 , roller 49 forces some substance along tube 51, just as it does to tube 38. Tube 51 is connected at both ends to container 36. Flow of the carrier substance through tube 51 is restricted by a plug 53 which may either be porous or have a narrow orifice. The restriction is such that the flow through plug 53 is much less than is being induced by the action of the roller 49 on tube 51 during opening of barrier arm 45. The result is that the section of tube 51 between the plug 53 and the roller 49 partially collapses. As tube 51 is thin walled and flexible this will not seriously impede the movement of the roller 49.

When the animal's actions open barrier arm 45 far enough the roller 49 traverses past the end of plate 52. As a result tube 51 will no longer be compressed by the roller 49 and carrier substance will flow freely back into the collapsed section of tube 51.

When the animal withdraws its head barrier arm 45 will begin to close due to the force exerted by spring 48. When the roller 49 meets plate 52 on the return stroke, it will start to compress tube 22 again, which will be full of carrier substance. Tube 51 though it can readily collapse can not readily expand beyond its normal tubular dimensions such that the carrier substance displaced by roller 45 has to flow through plug 53. The restriction that plug 53 creates is chosen to be such that the roller 49 takes much longer to traverse plate 52 on the return stroke such that most animals become disinterested and do not persist in their efforts to obtain another dose of carrier substance.

While the roller 49 is traversing plate 52 on the return stroke a suction 7 SOW will be created in the sections of tubes 38 and 42 between the roller 49 and the clamps 39 and 44. Under this suction the thin walled tubes 38 and 42 will collapse. Therefore, should the animal force open barrier arm 45 while the roller 49 is only part way through the return stroke, no fresh 5 poison or carrier substance will be dispensed. As tubes 38 and 42 will simply become less collapsed as poison and carrier substance flows into the collapsed section. Thus, not until roller 49 becomes clear of plate 52 (i.e. almost reset to its original position) can carrier substance and poison flow into the collapsed section of tubes 38 and 42 from containers 36 and 10 41.

When the roller 49 is finally clear of plate 52 the tubes 38 and 42 will rapidly become recharged with a full dose of poison and carrier substance.

Thus, by this means the likelihood of delivering partial doses will be 15 further diminished.

In a further alternative embodiment (not shown) the poison and carrier substance will not be separated such that container 41, tube 42 and inner nozzle 43 may be omitted. This embodiment is appropriate where there is no evidence that the poison is detectable by the target animals or where 20 learned aversion is not a significant problem.

In the embodiment illustrated in Figure 3 large non-target animals may be excluded from the dispenser in a number of ways: a) the cover 54 of the dispenser may be sufficiently long and narrow such that large animals cannot get their heads or tongues in to access the carrier substance and/or poison, and b) when the target animal is a tree climber, such as a rat or possum, 24 the dispenser can be mounted at a height such that non climbing animals are unable to reach it.

Aspects of the present invention have been described by way of example only and it should be appreciated that modifications and additions may be made thereto without departing from the scope thereof as defined in the appended claims.

Claims (34)

WHAT WE CLAIM IS;

1. A method of applying a control action to an animal characterised by the steps of: a) first, introducing the animal to a carrier substance, and then b) applying the control action wherein the applying of the control action is initiated by the presence of the animal, and wherein the control action is the addition of an active substance to the carrier substance.

2. A method of applying a control action as claimed in claim 1 wherein the carrier substance is a substance to which the animal is attracted.

3. A method of applying a control action as claimed in either claim 1 or claim 2 wherein the carrier substance is a food.

4. A method of applying a control action as claimed any one of claims 1 through 3 wherein the carrier substance is a fluid.

5. A method of applying a control action as claimed in claim 4 wherein the carrier substance is an oil.

6. A metjiod of applying a control action as claimed in claim 1 wherein the active substance is a fluid.

7. A method of applying a control as claimed in claim 6 wherein the active substance is a poison.

8. A method of applying a control action as claimed in claim 7 wherein the active substance is a hydrophilic compound in an aqueous solution. «. \ y\v- ! " J 27 0 0 1 with the carrier substance.

9. A dispenser of a fluid medium characterised in that the dispenser can be positioned above ground in such a manner that the fluid medium can exit the dispenser and under gravity form a fluid trail along a surface inclined away from the horizontal with respect to the dispenser, characterised in that the dispenser is capable of dispensing an active substance within a carrier substance when the dispenser detects the presence of an animal.

10. A dispenser as claimed in claim 10 wherein instead of the fluid medium forming a fluid trail it is dispensed so as to form a pool of fluid medium.

11. A dispenser as claimed in claim 9 wherein the carrier substance is a sweet syrup.

12. A dispenser as claimed in any one of claims 9 through to 11 wherein the carrier substance includes a nut-scented oil.

13. A dispenser as claimed in any one of claims 9 through to 12 wherein the carrier substance includes additives.

14. A dispenser as claimed in claim 13 wherein one additive is a viscosity modifier.

15. A dispenser as claimed in either claim 13 or claim 14 wherein one additive is a colouring agent.

16. A dispenser as claimed in any one of the preceding claims which include additives wherein the additive or additives are attractive to the animal. 27

17.

18.

19.

20.

21.

22.

23.

24.

25.

26.

27. 2? 0 © 11 A dispenser as claimed in any one of the preceding claims which include additives wherein the additive is isovaleric acid. A dispenser as claimed in any one of claims 9 through to 17 which includes a lure. A dispenser as claimed in claim 18 wherein the lure is a fluid. A dispenser as claimed in any one of claims 9 through to 19 which includes at least one container. A dispenser as claimed in claim 20 wherein the container is collapsible and substantially impermeable. A dispenser as claimed in any one of claims 9 through to 21 wherein the rate of fluid flow from the dispenser is controlled. A dispenser as claimed in claim 22 wherein the dispensing of the carrier substance is effected by the expansion of a material due to the material contacting with the air. A dispenser as claimed in claim 23 wherein the carrier substance is dispensed by utilising fluctuations in temperature. A dispenser as claimed in claim 24 wherein the carrier substance is dispensed via the action of a bi-metallic strip. A dispenser as claimed in claim 25 wherein the carrier substance is dispensed by utilising fluctuations in barometric pressure. A dispenser as claimed in claim 26 wherein the carrier substance is dispensed via the action of sealed bellows. A dispenser as claimed in claim 9 wherein the animal is detected by

28 the animal pushing on a barrier, the barrier restricting access to the source of the carrier substance.

29. A dispenser as claimed in claim 28 wherein the movement of the barrier activates delivery of the active substance to the carrier substance.

30. A dispenser as claimed in any one of claims 9 through to 29 which includes a timing device for delaying the resetting of the action which dispenses the active substance.

31. A dispenser as claimed in 30 wherein a peristaltic mechanism is used to dispense both the active substance and the carrier substance once the animal is detected.

32. A dispenser as claimed in either claim 30 or claim 31 wherein the dispenser has a mechanism such that the carrier substance is delivered before the active substance is dispensed, as well as carrier substance also being dispensed after the active substance has ceased to be dispensed.

33. A method of applying a control action substantially as described herein with reference to any example and/or drawing thereof.

34. A dispenser substantially as described herein with reference to any example and/or drawing thereof. the horticulture and food research institute of new zealand limited