Liquid Paraffin BP
Egg oiling with liquid paraffin BP is approved for use under the Control of Pesticides Regulations(COPR) but can only be used under licence provided by the Department of Environment, Food and Rural Affairs (DEFRA) under Section 16 (1) of the Wildlife and Countryside Act 1981.
It is an offence to interfere with a nest or its contents and therefore, before taking any action to remove a nest with or without eggs or chicks, or to oil eggs within a nest, permission must be sought from the Department of the Environment, Food and Rural Affairs (DEFRA).
Egg oiling is considered to be an extremely effective method of non-lethal and humane bird control but is not commonly used for the control of urban species such as the feral pigeon. Egg oiling is a method of egg treatment that is normally used for the control of ground nesting birds and is considered to be 100% effective if carried out at the correct time of year. The only exception to this rule would be where egg oiling is used for the control of roof-nesting birds such as the gull. Although the gull does not nest at ground level the process has been successfully adapted to be used as part of a gull control programme where birds are nesting in accessible areas at height.
Egg oiling involves the use of liquid paraffin BP to coat the shell of the egg in order to stop the embryo from developing. Liquid paraffin BP is a white mineral oil, commonly known as paraffin oil, which is available from chemists in small quantities or from chemical suppliers in 500 ml+ bottles for larger applications. When an egg is removed from the nest and fully immersed in liquid paraffin BP the oil blocks the pores of the egg, coating the underlying egg membrane and depriving the fertilised egg of oxygen. In order for the process to be completely effective the whole of the egg must be coated leaving no gaps or ‘dry’ areas.DEFRA recommends the use of a wide-necked container or small bucket for dipping the eggs. Once immersed in the liquid paraffin BP the egg must be turned 360° several times to ensure that the whole egg is coated. DEFRArecommends that the operator should wear protective gloves and a facemask to comply with Control of Pesticides Regulations (COPR) but confirms that a gloved hand will not remove liquid paraffin BP from a coated egg. Liquid sprays or sponges should not be used to coat the egg as these methods of coating may leave some areas of the shell untreated.
Once the egg has been dipped in liquid paraffin BP it should be allowed to drain before being replaced in the nest. The nests and eggs that have been treated should be marked to ensure that they are not revisited and re-oiled more often than is necessary – this reduces both labour and the quantity of liquid paraffin oil used. The major benefit of this method of egg treatment is that the parent will be unaware that the egg has been interfered with and will continue to incubate the eggs for the requisite period. Other methods of egg interference include the following:
- Breaking eggs (in the nest)
- Pricking eggs (using a pin or needle to make a hole in the shell of the egg that will allow bacteria to enter the egg as well as desiccating the contents)
- Removing eggs
- Cracking eggs
- Shaking eggs
- Removal of eggs and the provision of dummy eggs
All of these methods of egg interference are not only illegal, unless a licence has been obtained from DEFRA, but they are also ineffective, with the possible exception of removing eggs and replacing them with dummy eggs. When eggs are interfered with by any means other than egg oiling with liquid paraffin BP, the parent will normally re-lay another clutch of eggs immediately, rendering the process of interference pointless. Dummy eggs are likely to be accepted by the parent but only if the dummy egg is an exact replica of the real egg, not only in size and colour but also in weight. When using egg oiling it is important to be aware that if the target species commonly lays more than one clutch of eggs per season it is possible that re-laying will occur once the parent has incubated the treated eggs for the normal period (ie. for pigeon control this period would be 19 days).
As each and every species of bird lays a particular number of eggs (within a range), and as each species will spend varying periods laying and incubating their eggs, the timing of each egg oiling operation is critical. Some species of birds lay 12-15 eggs, some only 2 or 3. Some species breed all-year round others only produce one clutch per year. It is therefore also critically important to have in-depth knowledge of the target species before applying for a licence to oil eggs and before undertaking any oiling operations. As egg oiling operations can be highly labour-intensive, particularly where the control of waterfowl is concerned, a well planned and structured species-specific progamme must be provided. Failure to do so will compromise the success of the operation and dramatically reduce cost-efficiency.
Where the control of species such as the feral pigeon is concerned egg oiling can be an extremely effective method of control when combined with a loft-based control system. A system of this nature would normally involve the use of an artificial breeding facility such as pigeon loft where pigeons are encouraged to roost and breed as an alternative to their normal roosting and breeding sites. As pigeons breed all-year round any control system involving the use of egg oiling would need to be provided throughout the year with particular attention paid to the period March-October, this being the height of the breeding period. Although human interaction would be required throughout the whole year the act of oiling and marking eggs and nests in a loft-based environment would only take minutes per week.
Egg oiling is most commonly associated with the control of Canada goose populations due to the fact that Canada geese are becoming a growing problem in the UK with static populations of non-migratory birds increasing every year. As with the control of most species of bird, effective Canada goose control systems involve the use of several control techniques with egg oiling being considered to be one of the most effective options. Egg oiling regimes must be well planned and require nesting sites to be monitored prior to nests being built and clutches being laid. Clutches must be oiled immediately after the final egg has been laid on sites where multiple nests exist and for single breeding pairs the eggs should be oiled 3 days after the last egg has been laid. Canada geese start to lay in the second half of March with most eggs being laid in the first half of April. It would therefore be necessary to visit the breeding site 3 times; at the end of March, mid-April and the end of April. All eggs should be oiled throughout this period and by doing so it is highly unlikely that the parent will re-lay once past the end of the normal incubation period.
For the control of large gulls in urban environments egg oiling can be an extremely effective method of control, particularly when used as the main control option alongside the installation of deterrents and anti-perching devices. Gulls are normally colonial, sometimes breeding in mixed colonies and laying their eggs between mid-April and late June. Gulls will either breed on flat-roof areas, normally in numbers, or solitarily on or beside chimney pots or other difficult-to-access areas at height. Nests will need to be visited several times during the course of the breeding period to ensure that all the eggs are oiled. Clutches should be oiled as soon as incubation has started. As with Canada geese, constant monitoring will be required but as gulls tend to habituate to the same nesting site each year the monitoring process may be more straightforward. Although the installation of deterrents and anti-perching devices may be required, egg oiling, if carried out consistently and thoroughly, will be 100% successful as a birth control option. It may also have the effect of moving the birds on to other breeding sites permanently due to their lack of success in rearing young on the site concerned. This process is likely to take 2 to 3 seasons before the birds permanently desert the site.
Egg oiling is a cheap, humane and 100% effective method of control that can be used in a variety of situations and for the control of a wide variety of bird species. When used for the control of some species, such as wildfowl in rural areas, the act of oiling may be labour-intensive, thereby increasing the cost of the operation. However, the fact that this method can be 100% effective relative to conventional controls such as shooting, which are completely ineffective (and in some cases act to increase population size as a result of rejuvenation), egg oiling has to be considered to be one of the most effective methods of control available.
The Department of the Environment, Food and Rural Affairs (DEFRA) is the UK’s Government body that oversees the Wildlife and Countryside Act and produces legislation to which the pest control industry must adhere. The following information is taken from a document provided on DEFRA website entitled: ‘Review of international research regarding the effectiveness of auditory bird scaring techniques and potential alternatives’. By J Bishop, H McKay, D Parrott and J Allan. For the purpose of this review we have included a section on nest destruction as this control option is often tried and found to fail prior to resorting to egg oiling.
Egg Destruction and Oiling
“Egg destruction is used to reduce the local population of pest birds and in the UK it requires a licence from Defra. Eggs can be destroyed by several methods. Straightforward egg removal can encourage re-laying unless the eggs are replaced by hardboiled or wooden replicas (Baker et al. 1993). The pricking of eggs with a needle allows bacteria to enter the egg as well as desiccate its contents (French and Parkhurst 2001), but some pricked eggs may still hatch and birds may abandon clutches to relay.
Egg oiling is a cheaper, more effective and more humane method of egg control. It involves coating the egg shells with oil such as liquid paraffin (Baker et al.1993). This stops air from passing through the shell to the embryo and prevents it from developing properly. Baker et al. (1993) tested this method on Canada geese and achieved a 100% success rate; none of the 231 treated eggs hatched. They also pricked some eggs and these too did not hatch, but they were incubated for significantly less time, allowing the adults to relay elsewhere.”
“This technique, using white mineral oil, was also effective on ring-billed and herring gull eggs, though some eggs (8-9%) sprayed early in incubation or sprayed with only a small quantity of oil late in incubation, did hatch (Christens and Blokpoel 1991). For total success, it was recommended that spraying should be undertaken three times during incubation. Although this should be more effective it is more labour-intensive and so less cost-effective.”
“The sole use of egg destruction is unlikely to reduce a local population in the longterm. It is a time-consuming process as all nests have to be located and treated, and this may be hindered by problems of access. The timing of destruction is important and any reduction in a population caused by the loss of young birds may well be offset by immigration of new birds from nearby non-treated areas.”
“The technique has been approved under the Control of Pesticides Regulations (COPR) but can only be used under a licence issued by the Department of Environment, Food and Rural Affairs (Defra) under Section 16(1) of the Wildlife and Countryside Act, 1981.”
“Nest destruction, like egg destruction, requires a licence in the UK. It is a time consuming though relatively inexpensive control technique, and may help to control a local pest species. This technique was used to control double-crested cormorants in America, and reduce their negative impacts on the nesting habitats of other colonial waterbirds, as well as help to restore the fish community (Farquhar et al. 2000). During weekly visits nests on the ground were removed by hand and those in trees dislodged with a telescopic pole. The nesting material was scattered to discourage rebuilding. Since the nest removal programme began there has been no successful cormorant breeding in the area.”
“Ickes et al. (1998) recommended nest and egg removal for ground-nesting colonies of gulls but found that the technique was unlikely to reduce the number of nesting gulls in a given area, but it moved the problem as the gulls dispersed to recolonise other sites. Nest and egg removal and just egg removal were found to be equally effective but the former technique was approximately 60% more labour intensive. This made it more expensive.”
“In general, the use of other scaring methods in addition to nest disturbance and destruction is more likely to cause abandonment of an area by a bird pest species (Blokpoel and Tessier 1992, cited in Ickes et al. 1998).”
Paraffin BP is widely available through high street chemists or in large quantities from chemical suppliers. The cost for larger quantities varies considerably but for a 180 kilo drum of liquid paraffin BP, from a large chemical supplier, the cost would be approximately £300.00. To put this in perspective, 1 kilo would be sufficient for most users to oil a considerable number of nests several times in one season.
For small quantities the price of a small bottle of liquid paraffin BP from a chemist is £1.10 for a 150ml bottle.
The following comment is made by a spokesperson for the Pigeon Control Advisory Service, an organisation that has widely recommended the use of egg oiling as a means of controlling a variety of avian species:
“Many of our clients have used egg oiling to great effect for the control of gulls, ducks, Canada geese and pigeons. This method of control is completely effective when the user is prepared to undertake regular monitoring and oiling according to the breeding habits of the target species. In fact this is the only method of bird control that we have found to be 100% effective.”
“The user has to be prepared to make the effort to monitor and identify nests, as well as undertake 2 or 3 oiling operations per year, but if clients follow the advice they are given they will be rewarded with an extremely effective control system that is humane and non-invasive.”
“Where artificial breeding facilities are used by clients for the purpose of pigeon control we will normally offer the option of using egg oiling to treat eggs as an alternative to egg removal and replacement with dummy eggs. Both methods are effective and in each case the adult is unaware that the eggs have been interfered with, but egg oiling has the edge over the use ofdummy eggs. In some cases dummy eggs are rejected by the parent and they have re-laid as a result, but to date we have not had an instance where oiled eggs have been deserted. The only possible down-side of egg oiling, relative to removal and replacement with dummy eggs, is that it takes a couple of minutes longer per week, but this is the only negative.”
Egg oiling is a rare phenomenon in the world of bird control – it is a control that is 100% effective. Although there are anti-perching products, such as the anti-roosting spike, that are 100% effective when installed according to manufacturers instructions, there are no other scaring, deterring or birth control products that are anything like as effective as egg oiling. Egg oiling is a versatile control option that can be effective with a wide variety of bird species and in countless applications.
Although the monitoring process and resultant oiling operations may be time consuming in some applications, the long-term advantage is that the target species may simply cease using the site for the purpose of breeding if they have been unsuccessful in breeding for several consecutive years. This is particularly the case where roof-nesting gulls are concerned. Mature roof nesting gulls return to the same breeding site each year and unless physically prevented from doing so are unlikely to be persuaded to go elsewhere. If their eggs are oiled for several consecutive years and they produce no young, the birds may associate the unsuccessful breeding attempts with the site rather than with any other factor. As a result the birds may move on to another site without the need to resort to any other control option. When egg oiling is combined with the provision of anti-perching products and possibly some type of visual or bio-acoustic scarer, the user will have a highly effective and comprehensive control system.
Egg oiling will hold appeal for a majority of those experiencing bird-related problems as the process of oiling is extremely simple to undertake without the need for special training or protective clothing other than gloves and a facemask. Paraffin oil is also extremely inexpensive to buy and very little is used during the course of an oiling operation. Therefore the main cost implications are simply man-hours required to monitor nest sites and oil eggs.
One of the major advantages of egg oiling is that it is humane and non-lethal. Egg oiling offers the user a bird-friendly product that is not only inexpensive to provide but that is also highly effective as a control option. Lethal control has historically been used to control many of the species that we commonly associate with egg oiling, including Canada geese and roof-nesting gulls, but lethal control is a completely ineffective and often controversial control option. In a majority of cases where lethal control is used in an attempt to reduce population size on commercial sites, employees will react in an extremely negative way to what they see as unnecessary killing. This, combined with the fact that lethal controls such as shooting and cage trapping can actually have the opposite effect and increase population size, demonstrates the effectiveness of egg oiling as an excellent all-round and popular alternative to invasive controls.
For anyone considering egg oiling as a control option it must be stressed that an in-depth understanding of the target species and its breeding habits is essential. Once the user is satisfied that he or she is fully conversant with the target species and is in a position to provide the necessary time to monitor breeding and undertake oiling, this method can be used by virtually anyone. Egg oiling can clearly be used in large-scale commercial applications but it can also be used to great effect by the individual who has a minor problem with, for example, nesting pairs of ducks in their waterside garden. In this application monitoring would be simple and straightforward and the benefit would be that there would be virtually no cost associated with the control. Neither would this form of birth control cause any controversy based on the fact that it is non-invasive and bird-friendly.
PDF on DEFRA website entitled: ‘Review of international research regarding the effectiveness of auditory bird scaring techniques and potential alternatives’. By J Bishop, H McKay, D Parrott and J Allan.
Also commonly known as:
Egg dipping, birth control, egg interference, egg control, contraceptive control
Relevance to pigeon control:
Low relevance to pigeon control for conventional applications but this method is increasingly being used where loft or dovecote-based pigeon control systemsare being employed. Egg oiling is more commonly used for the control of waterfowl such as Canada geese and in recent years for the control of roof-nesting gulls
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