1080 bait and delivery
Table 1. Sowing rate of 1080 baits have declined significantly since the 1970s [11].
The design and delivery methods of 1080 bait has evolved since its introduction to increase its efficacy on target animals and to limit non-target bykills. Baits that have been used in New Zealand include cereal baits, carrot baits, paste and gel baits [1].
Cereal baits are manufactured by mixing 1080 with bran, kibbled grain and sugar [2]. It is also essential for the cereal baits to be dyed green and cinnamon flavoured [3]. The green dye makes it less attractive to birds and the flavouring masks the odour of 1080 to possums, and deer repellent can also be added [4] [5].
1080 and non-target species
When 1080 baits are mixed with primary repellents (e.g. colour, d-pulegone)and secondary repellents (e.g. illness-inducing materials such as anthraquinone), it prevents some species of birds from pecking the bait [6]. However the mixture may change its effectiveness on possums.
Repellents can have different effects on various non-target species. Cinnamide for instance, will put off kea while robins will readily peck at cinnamon-flavoured, green bait [7].
Deer repellents can also be added to 1080 bait. ERPRO Deer Repellent (EDR) is effective in deterring deer from eating baits but does not deter possums [8]. There is no evidence from trial and operational results that possum kills affected by the addition of EDR to standard carrot or cereal 1080 baits.
The design of carrot baits has also been improved to reduce the risk of non-target species bykill. Weighing about 6 to 12 grams, the size of carrot baits are too big for most non-target species [9].Small pieces of carrot bait (‘chaff’) that are easy for birds to eat are no longer used. Although carrot baits are rarely used in aerial, in some parts of the country they are used to control rabbits in open country [10].
How much 1080 is being used in baits?
To be effective it is recommended that baits should include 1.5 grams of 1080 per kilogram (i.e. 0.15% 1080 pellets) [12]. A cage study shows more than 35% of possums that consumed cereal baits with lower toxicity (i.e. 0.08% 1080 pellets) survived.
Cereal baits are manufactured by mixing 1080 with bran, kibbled grain and sugar [2]. It is also essential for the cereal baits to be dyed green and cinnamon flavoured [3]. The green dye makes it less attractive to birds and the flavouring masks the odour of 1080 to possums, and deer repellent can also be added [4] [5].
1080 and non-target species
When 1080 baits are mixed with primary repellents (e.g. colour, d-pulegone)and secondary repellents (e.g. illness-inducing materials such as anthraquinone), it prevents some species of birds from pecking the bait [6]. However the mixture may change its effectiveness on possums.
Repellents can have different effects on various non-target species. Cinnamide for instance, will put off kea while robins will readily peck at cinnamon-flavoured, green bait [7].
Deer repellents can also be added to 1080 bait. ERPRO Deer Repellent (EDR) is effective in deterring deer from eating baits but does not deter possums [8]. There is no evidence from trial and operational results that possum kills affected by the addition of EDR to standard carrot or cereal 1080 baits.
The design of carrot baits has also been improved to reduce the risk of non-target species bykill. Weighing about 6 to 12 grams, the size of carrot baits are too big for most non-target species [9].Small pieces of carrot bait (‘chaff’) that are easy for birds to eat are no longer used. Although carrot baits are rarely used in aerial, in some parts of the country they are used to control rabbits in open country [10].
How much 1080 is being used in baits?
To be effective it is recommended that baits should include 1.5 grams of 1080 per kilogram (i.e. 0.15% 1080 pellets) [12]. A cage study shows more than 35% of possums that consumed cereal baits with lower toxicity (i.e. 0.08% 1080 pellets) survived.
Application of Ground Baiting Stations (Source: AHB)
Aerial application
Aerial operations provide a cost-efficient means of reaching areas that ground operations simply cannot. Compared to ground operations, aerial operations can cover areas as large as 46,000 ha per operation [13]. Due to economies of scale, this method of delivery is more affordable than ground operations. An aerial 1080 operation (including pre-feeding) can cost as little as $12 to $16 per hectare [14].
Average sowing rates of 1080 cereal baits have also declined significantly from over 30 kg of bait per hectare in the 1950s to under 2 kg of bait per hectare today – equivalent to about four baits in an area the size of a tennis court [15].
The future of aerial 1080 operations
Landcare Research has developed a more efficient method for aerial delivery of 1080 baits in clusters, rather than evenly, which could potentially reduce toxin use [16]. Despite using 60% less 1080 bait (1 kg/ha), the reductions in possum activity indices achieved with cluster sowing (98.4%) were similar to those achieved with broadcasting sowing (97.8%) [17].
A cluster baiting method has been trialed with the baiting rate as low as 0.17 Kg/ha, significantly lower than normal sowing rate of 2 Kg/ha.
In Otago, a new strip sowing method of applying bait is currently being trialed. Initial results show similar kill rates to other methods with a reduced amount of 1080 needed.
Ground operations
Ground operations are ideal for covering areas that have easy access and easy terrain. The main advantage of ground-baiting operations is their ability to limit non-target species by-kill. The baits are hand placed in bait stations that allow the target in but deter other animals, or applied directly to the ground [18].
While ground operations may provide greater control over the operation, they are costly. The costs vary from $4 a hectare in easily accessible land to $80 per hectare in areas with difficult vegetation cover [19].
With the average coverage area of only 4,000 hectare for each operation, ground baiting is not as time efficient as aerial operations.
Aerial operations provide a cost-efficient means of reaching areas that ground operations simply cannot. Compared to ground operations, aerial operations can cover areas as large as 46,000 ha per operation [13]. Due to economies of scale, this method of delivery is more affordable than ground operations. An aerial 1080 operation (including pre-feeding) can cost as little as $12 to $16 per hectare [14].
Average sowing rates of 1080 cereal baits have also declined significantly from over 30 kg of bait per hectare in the 1950s to under 2 kg of bait per hectare today – equivalent to about four baits in an area the size of a tennis court [15].
The future of aerial 1080 operations
Landcare Research has developed a more efficient method for aerial delivery of 1080 baits in clusters, rather than evenly, which could potentially reduce toxin use [16]. Despite using 60% less 1080 bait (1 kg/ha), the reductions in possum activity indices achieved with cluster sowing (98.4%) were similar to those achieved with broadcasting sowing (97.8%) [17].
A cluster baiting method has been trialed with the baiting rate as low as 0.17 Kg/ha, significantly lower than normal sowing rate of 2 Kg/ha.
In Otago, a new strip sowing method of applying bait is currently being trialed. Initial results show similar kill rates to other methods with a reduced amount of 1080 needed.
Ground operations
Ground operations are ideal for covering areas that have easy access and easy terrain. The main advantage of ground-baiting operations is their ability to limit non-target species by-kill. The baits are hand placed in bait stations that allow the target in but deter other animals, or applied directly to the ground [18].
While ground operations may provide greater control over the operation, they are costly. The costs vary from $4 a hectare in easily accessible land to $80 per hectare in areas with difficult vegetation cover [19].
With the average coverage area of only 4,000 hectare for each operation, ground baiting is not as time efficient as aerial operations.
References:
[1] National Possum Control Agencies (2008). Questions and Answers on 1080. Retrieved from http://www.doc.govt.nz/documents/conservation/threats-and-impacts/animal-pests/wanganui/national-possum-control-agencies-questions-and-answers-on-1080.pdf
[2] The Department of Conservation. How 1080 is used. Retrieved from http://www.doc.govt.nz/conservation/threats-and-impacts/animal-pests/methods-of-control/1080-poison-for-pest-control/the-use-of-1080-for-pest-control/4-information-about-1080/4_3-how-1080-is-used/
[3] Ibid.
[4] Ibid.
[5] Department of Conservation. Deer Repellent on 1080. Retrieved from http://www.doc.govt.nz/parks-and-recreation/hunting/what-to-hunt/deer/deer-repellent-on-1080/
[6] Clapperton, B, K., Morgan, D, K, J., Day, T, D., Oates, K, e., Beath, A, M., Cox, N, R., & Matthews, L, R. 2013. Efficacy of bird repellents at deterring North Island robins (Petroica australis longipes) and tomtits (P. Macrocephala toitoi) from baits. New Zealand Journal of Ecology, 38(1), 116-123.
[7] Ibid.
[8] Morris, G,A. (2007). EPRO deer repellent for baits used in possum control. Landcare Research Contract Report LC0607/147. Lincoln, Landcare Research p20.
[9] The Department of Conservation. How 1080 is used. Retrieved from http://www.doc.govt.nz/conservation/threats-and-impacts/animal-pests/methods-of-control/1080-poison-for-pest-control/the-use-of-1080-for-pest-control/4-information-about-1080/4_3-how-1080-is-used/
[10] DOC has not used carrot baits to control possums or rats in forests since 2008, while the AHB has used carrots in forests in 15 different operations (ERMA, unpublished data).
[11] PCE (2010). Evaluating the use of 1080: predators, poisons and silent forests. Parliamentary Commissioner for the Environment, Wellington.
[12] Landcare Research. 2011. Possum control – aerial applications of 1080 cereal pellets (with optional deer repellent). Retrieved from https://pestdss.landcareresearch.co.nz/Content/BestPractice/16%20Possums%20-%201080%20aerial-%20cereal%20pellets.pdf
[13] 98 ERMA. 2009. Annual report on the aerial use of 1080. Environmental Risk Management Authority, Wellington.
[14] PCE (2010). Refer to [11], above.
[15] Ibid.
[16] Nugent, Graham., & Morriss, Grant A. 2013. Delivery of toxic bait in clusters: a modified technique for aerial poisoning of small mammal pests. New Zealand Journal of Ecology,37(2), 246-255.
[17] Ibid.
[18] PCE (2010). Refer to [11], above.
[19] Ibid.
[1] National Possum Control Agencies (2008). Questions and Answers on 1080. Retrieved from http://www.doc.govt.nz/documents/conservation/threats-and-impacts/animal-pests/wanganui/national-possum-control-agencies-questions-and-answers-on-1080.pdf
[2] The Department of Conservation. How 1080 is used. Retrieved from http://www.doc.govt.nz/conservation/threats-and-impacts/animal-pests/methods-of-control/1080-poison-for-pest-control/the-use-of-1080-for-pest-control/4-information-about-1080/4_3-how-1080-is-used/
[3] Ibid.
[4] Ibid.
[5] Department of Conservation. Deer Repellent on 1080. Retrieved from http://www.doc.govt.nz/parks-and-recreation/hunting/what-to-hunt/deer/deer-repellent-on-1080/
[6] Clapperton, B, K., Morgan, D, K, J., Day, T, D., Oates, K, e., Beath, A, M., Cox, N, R., & Matthews, L, R. 2013. Efficacy of bird repellents at deterring North Island robins (Petroica australis longipes) and tomtits (P. Macrocephala toitoi) from baits. New Zealand Journal of Ecology, 38(1), 116-123.
[7] Ibid.
[8] Morris, G,A. (2007). EPRO deer repellent for baits used in possum control. Landcare Research Contract Report LC0607/147. Lincoln, Landcare Research p20.
[9] The Department of Conservation. How 1080 is used. Retrieved from http://www.doc.govt.nz/conservation/threats-and-impacts/animal-pests/methods-of-control/1080-poison-for-pest-control/the-use-of-1080-for-pest-control/4-information-about-1080/4_3-how-1080-is-used/
[10] DOC has not used carrot baits to control possums or rats in forests since 2008, while the AHB has used carrots in forests in 15 different operations (ERMA, unpublished data).
[11] PCE (2010). Evaluating the use of 1080: predators, poisons and silent forests. Parliamentary Commissioner for the Environment, Wellington.
[12] Landcare Research. 2011. Possum control – aerial applications of 1080 cereal pellets (with optional deer repellent). Retrieved from https://pestdss.landcareresearch.co.nz/Content/BestPractice/16%20Possums%20-%201080%20aerial-%20cereal%20pellets.pdf
[13] 98 ERMA. 2009. Annual report on the aerial use of 1080. Environmental Risk Management Authority, Wellington.
[14] PCE (2010). Refer to [11], above.
[15] Ibid.
[16] Nugent, Graham., & Morriss, Grant A. 2013. Delivery of toxic bait in clusters: a modified technique for aerial poisoning of small mammal pests. New Zealand Journal of Ecology,37(2), 246-255.
[17] Ibid.
[18] PCE (2010). Refer to [11], above.
[19] Ibid.
