**2. Methods of controlling bird mortality**

366 Pesticides in the Modern World - Risks and Benefits

cryptic animals such as zebra and chameleons. Camouflage comes from the French word 'camoufler' which means to disguise or conceal through a disguise and its evolutionary significance has been gaining wide scientific support as a mechanism that reduces the risk of detection (Merilaita et al., 1998, Zug et al. 2001; Merilaita, 2003, Schmidt et al., 2004, Frankel

The principle of camouflage inspired and guided the development of this research. Seeds of wheat, corn and rice, when treated with systemic pesticides, would receive dyed camouflage, making them similar to the soil where they were planted. This cover would preferably be processed on the same machine that performs pesticide treatment, moreover, it could not impair the mechanical planting or germination. The camouflage should have low operational and financial cost, as well as been non-toxic. Thus, seeds that were not buried by the planting machine, remaining dangerously exposed to granivorous birds, would count with a camouflage whose effectiveness would be favored by organic matter not decomposed, by the irregularities of the soil, and by the contrasts between light and shadows on the soil surface, even though the birds actively seeked them on the ground. Birds attack the agricultural fields because they are abundant sources of food readily accessible, requiring low energy expenditure. If food becomes difficult to find, to ingest, and to digest, birds will spend more time and energy to forage. Having them difficulty to maintain a certain rate-making energy, the theory of optimal foraging predicts that animals

The aim of this paper is to present the method of concealment of seeds and how it was designed, with respect to the material tests and seed germination. Results obtained from these assessments show that camouflages can increase the germination rate of seeds and that 'home-made' forms of camouflage can be as efficient, if not better than camouflage produced by industrial processes. Also, camouflage do not need high operating or financial costs, it can be applied to seeds using the usual machinery of seed pesticides treatment on

Fig. 4. Camouflaged seeds can be visible, representing risk of poisoning for birds, if it were not completely buried and were seeded outside the plowed soil of the planting, or in

absence of non decomposed organic matter on the soil surface.

et al. 2004; Merilaita & Lind, 2005, Cuthill et al., 2005).

will look for another food source (Avery, 2002, Begon et al., 2006).

commercial scale plantations.

An study consolidating three experiments was conducted in Paraná and São Paulo States to evaluate if camouflaged seeds could minimize the mortality of wild birds, caused by the ingestion of commercial seeds treated with pesticides and rhodamine B (Almeida et al., 2010a). When put all together, the three experiments were summing up to 15,896 kg of seeds, sowed in 111.46 hectares. Alternative strategies for reducing mortality, like the use of carbofuran without rhodamine B and the use of carbosulfan. Carbofuran without rhodamine B gives a 'beige' hue to seeds and could make them less attractive to birds, representing economic savings at planting. Carbosulfan, a carbamate with insecticidal and nematicidal properties and with a lethal dose circa 20 times weaker than carbofuran, could act as a chemical repellent if the birds were able to link the poisoning symptoms to the food, halting the consumption before dying.

Experiments in rice and wheat plantations were performed in regions where mortality of birds, coming from the ingestion of seeds treated with pesticides, was reported by farmers and they were performed in the planting seasons, when numerous flocks of birds were present.

Fig. 5. Installation of an experiment of planting in commercial scale using seeds poisoned with carbofuran.

Camouflage of Seeds, a Control Method of the Bird Mortality in Grain Crops 369

The total experimental area consisted of 10 ha, divided into 1 ha parcels. Five hectares were assigned to each treatment. The amount of seeds in parcels and among treatments was

Experiment 2. The treatments applied to the rice seeds were: i) red seeds treated with carbofuran and rhodamine B; ii) brown seeds, camouflaged with powdered dye and treated

For treating the seeds, powder carbosulfan, in a concentration of 350 g / kg, was used; the dosage was 3 kg powder every one hundred of seeds. Carbosulfan toxicity for humans was LD50 = 212 mg / kg. Treatments were made to seven parcels of 0.26 ha, adding up to 5.46 ha. 100 kg of seeds were used per hectare. The amount of seeds in parcels and among

Experiment 3. The following treatments, applied to the wheat seeds, were tested: i) red seeds treated with carbofuran and rhodamine B; ii) brown seeds, camouflaged with liquid dye, treated with carbofuran; iii) beige seeds, treated with carbofuran without rhodamine B;

The total assay area was 96 ha, divided into four equal parcels of 24 ha, each one receiving

The mortality mounted to 296 birds, distributed into 11 species. Eared doves were the most numerous victims, with 263 deaths. The consumption of camouflaged seeds was lower than that of commercial seeds treated with rhodamine. The mortality caused by seeds with rhodamine was higher than the one caused by camouflaged seeds. When powder dye camouflaging was used, the mortality range decrease in 75.5 to 100%, and the range of

Fig. 7. The dissection of the Ruddy ground dove (*Columbina talpacoti*), showing one wheat camouflaged seed, which killed the bird. This bird was one of the 73 victims who died with

The brown color and the powder dye, rich in iron oxide, decrease the spectral reflectance (Hartley et al., 2000; Demattê et al., 2003; Espig et al., 2005; Almeida, 2006) of seeds in the wave lengths visible by the Passeriforms and Columbidae (Hart, 2001), making them similar

with carbofuran; iii) red seeds treated with carbosulfan and rhodamine B.

iv) brown seeds, camouflaged with powder dye, treated with carbofuran.

consumption decrease in 57.4 to 99%, relative to the other treatments.

3,500 kg of seeds related to the treatments (145 kg / ha).

only one seed in the crop, poisoned early in digestion.

balanced. A total of 1,350 kg of seeds were used.

treatments was balanced.

The powdered brown-colored dye used in to camouflage the seed was obtained through mixing red, black, blue, brown and yellow powdered dyes, reaching a hue similar to the soil samples previously gathered. The liquid dye used in the other camouflaging was obtained by mixing red, blue, yellow, black and brown pigments in water, and then adding the slurry to the carbofuran syrup in proportions which allowed a proper camouflage to match the region's soil color. The process of camouflaging seeds was performed in the same machine used in the treatment of seeds with carbofuran or carbosulfan.

For treating the seeds, carbofuran in a concentrated suspension of 350 g/l was used. The dosage of carbofuran used for wheat or rice seeds was 2 l for 100 kg. Carbofuran's toxicity (human LD50 = 8-12 mg/kg) was so high that small (~ 40 g) and medium-sized birds (~120 g) ingesting seeds from the experiment often died *in situ*. Sowing was conventional in dry land, made by a tractor-mounted gravity seed drill implemented with a seed drill over plowed soil in the traditional planting system (Figure 5).

The tested treatments were disposed in parcels no further than 700 m away from each other. The amount of seeds in parcels and among treatments was balanced. The average plot size was 8.54 hectares (n = 6; standard deviation = 7.8), and there were 144.2 kg of seeds per hectare. Two searches for dead birds were made per day in every parcel. The searches parties were composed of two, three or sometimes four people walking slowly (~ 3 km/h) or in a pick-up truck (~ 5 km/h) and were gathered within and around the parcels (Figure 6).

Fig. 6. Birds feeding on seeds poisoned with carbofuran in a experiment of planting.

Bird carcasses were collected and identified. The food present in the digestive tract of bird carcasses was collected separately as it follows: i) crop and esophagus; ii) proventriculus; and iii) gizzard (Figure 7). The seeds from each treatment were counted. The numerical variations from dead birds and consumed seeds between treatments were checked with analysis on variance, considering days of experimental exposure as repeated samples. Birds which were able to ingest seeds from more than one treatment were excluded from the analysis.

The Experiment 1 was conducted using wheat seeds, and the treatments were: i) red seeds treated with carbofuran and rhodamine B; ii) brown seeds camouflaged with powder dye, treated with carbofuran.

The powdered brown-colored dye used in to camouflage the seed was obtained through mixing red, black, blue, brown and yellow powdered dyes, reaching a hue similar to the soil samples previously gathered. The liquid dye used in the other camouflaging was obtained by mixing red, blue, yellow, black and brown pigments in water, and then adding the slurry to the carbofuran syrup in proportions which allowed a proper camouflage to match the region's soil color. The process of camouflaging seeds was performed in the same machine

For treating the seeds, carbofuran in a concentrated suspension of 350 g/l was used. The dosage of carbofuran used for wheat or rice seeds was 2 l for 100 kg. Carbofuran's toxicity (human LD50 = 8-12 mg/kg) was so high that small (~ 40 g) and medium-sized birds (~120 g) ingesting seeds from the experiment often died *in situ*. Sowing was conventional in dry land, made by a tractor-mounted gravity seed drill implemented with a seed drill over

The tested treatments were disposed in parcels no further than 700 m away from each other. The amount of seeds in parcels and among treatments was balanced. The average plot size was 8.54 hectares (n = 6; standard deviation = 7.8), and there were 144.2 kg of seeds per hectare. Two searches for dead birds were made per day in every parcel. The searches parties were composed of two, three or sometimes four people walking slowly (~ 3 km/h) or in a

pick-up truck (~ 5 km/h) and were gathered within and around the parcels (Figure 6).

Fig. 6. Birds feeding on seeds poisoned with carbofuran in a experiment of planting.

able to ingest seeds from more than one treatment were excluded from the analysis.

treated with carbofuran.

Bird carcasses were collected and identified. The food present in the digestive tract of bird carcasses was collected separately as it follows: i) crop and esophagus; ii) proventriculus; and iii) gizzard (Figure 7). The seeds from each treatment were counted. The numerical variations from dead birds and consumed seeds between treatments were checked with analysis on variance, considering days of experimental exposure as repeated samples. Birds which were

The Experiment 1 was conducted using wheat seeds, and the treatments were: i) red seeds treated with carbofuran and rhodamine B; ii) brown seeds camouflaged with powder dye,

used in the treatment of seeds with carbofuran or carbosulfan.

plowed soil in the traditional planting system (Figure 5).

The total experimental area consisted of 10 ha, divided into 1 ha parcels. Five hectares were assigned to each treatment. The amount of seeds in parcels and among treatments was balanced. A total of 1,350 kg of seeds were used.

Experiment 2. The treatments applied to the rice seeds were: i) red seeds treated with carbofuran and rhodamine B; ii) brown seeds, camouflaged with powdered dye and treated with carbofuran; iii) red seeds treated with carbosulfan and rhodamine B.

For treating the seeds, powder carbosulfan, in a concentration of 350 g / kg, was used; the dosage was 3 kg powder every one hundred of seeds. Carbosulfan toxicity for humans was LD50 = 212 mg / kg. Treatments were made to seven parcels of 0.26 ha, adding up to 5.46 ha. 100 kg of seeds were used per hectare. The amount of seeds in parcels and among treatments was balanced.

Experiment 3. The following treatments, applied to the wheat seeds, were tested: i) red seeds treated with carbofuran and rhodamine B; ii) brown seeds, camouflaged with liquid dye, treated with carbofuran; iii) beige seeds, treated with carbofuran without rhodamine B; iv) brown seeds, camouflaged with powder dye, treated with carbofuran.

The total assay area was 96 ha, divided into four equal parcels of 24 ha, each one receiving 3,500 kg of seeds related to the treatments (145 kg / ha).

The mortality mounted to 296 birds, distributed into 11 species. Eared doves were the most numerous victims, with 263 deaths. The consumption of camouflaged seeds was lower than that of commercial seeds treated with rhodamine. The mortality caused by seeds with rhodamine was higher than the one caused by camouflaged seeds. When powder dye camouflaging was used, the mortality range decrease in 75.5 to 100%, and the range of consumption decrease in 57.4 to 99%, relative to the other treatments.

Fig. 7. The dissection of the Ruddy ground dove (*Columbina talpacoti*), showing one wheat camouflaged seed, which killed the bird. This bird was one of the 73 victims who died with only one seed in the crop, poisoned early in digestion.

The brown color and the powder dye, rich in iron oxide, decrease the spectral reflectance (Hartley et al., 2000; Demattê et al., 2003; Espig et al., 2005; Almeida, 2006) of seeds in the wave lengths visible by the Passeriforms and Columbidae (Hart, 2001), making them similar

Camouflage of Seeds, a Control Method of the Bird Mortality in Grain Crops 371

Rhodamine B, ii) carbosulfan and Rhodamine B; and in the second wheat trial: i) carbofuran and Rhodamine B; ii) carbosulfan and Rhodamine B; iii) carbofuran and Rhodamine B plus methiocarb. Methiocarb was added to the seeds, after they received treatment with carbofuran and Rhodamine B. The dose of methiocarb powder was equal to 1 kg for each

The resulting mortality of this experiment mounted to three species, distributed into 314 birds, which 308 were Eared Doves deaths. In the first trial plots, where seeds treated with carbofuran were sown, 109 birds were found dead, and in those treated with carbosulfan, 40 were recovered. These results differed significantly, suggesting that a greater mortality was caused by carbofuran, and that the use of carbosulfan may lessen the impact of grain farming on wild birds. In turn, data clearly showed that carbosulfan use will still result in notable mortality. Further, some birds were noted as having been visibly poisoned by carbosulfan, yet managed to leave the test plot and (though disorientated) reach refuge outside the test area (ca 550 metres away). It was not possible to know if these poisoned birds recovered or died after escaping the experimental plot. Given these points, just like in the anterior experiment, it's necessary consider: i) the number of deaths recorded was not accurate, since poisoned birds may have left the test plot; ii) carbosulfan didn't act as a secondary repellent which interrupts consumption; iii) birds poisoned with carbosulfan had a greater tendency to reach the adjacent forest, where they may be preyed upon by forest species, therefore be hidden from farmers, researchers and hence, public opinion. These points raise questions regarding the principle that carbosulfan may not be used as a substitute for carbofuran. The findings reported here suggest that carbosulfan is probably

100 kg seeds.

not an effective alternative to carbofuran.

Fig. 8. The distribution of seeds in a plot of the removal experiment.

to the soil. In addition, camouflaged coating, made with the powder, presents an opaque surface and, for this reason, has less shine than seeds treated with rhodamine, being less conspicuous (Schmidt et al., 2004; Cuthill et al., 2005). Besides, it is possible that there wasn't search image for brown seeds, and in accordance with the optimal foraging theorem, greater energy would be required to consume and locate such seeds (Avery, 2002; Begon et al. 2006). However, the ingestion of small grits to help crush foods is a common aspect in the behavior of several bird Families (Sick, 1997). So, it is possible that brown-dyed seeds are less removed due to a set of factors linked to the camouflaging phenomenon like background match, avoiding well defined contours and color contrasts (Merilaita 2003, Frankel et al., 2004, Schmidt et al., 2004) and not only due to the aversion to the brown color, as tested by Hartley et al. (1999, 2000). They tried blue and brown with relative success at avoiding the consumption of poisoned grains by birds, suggesting such colors would cause aversion.

The notable ingestion of red seeds suggests that this color, attributed by rhodamine B, is not aversive, but attractive (Schmidt et al., 2004; Cuthill et al., 2005), which is in contradiction to the findings of Avery & Mason (1997) and Nelms & Avery (1997). This color's spectral behavior, in the wavelengths visible by the birds, is similar to yellow and orange (Schmidt et al., 2004), which are contrasting and conspicuous and similar to beige. This may explain the high consumption of seeds treated with carbofuran without rhodamine B. Thus, whether the reddish hue from rhodamine B, or the beige color, coming from the syrup of carbofuran without rhodamine B, there is a higher probability of birds detecting and ingesting less camouflaged seeds.

The replacement of carbofuran with carbosulfan also appeared to reduce mortality, but carbosulfan mortality is thought to have been underestimated because of the apparent movement of affected birds after exposure. Besides, the possible carbosulfan action as a gustative repellent was not checked and, in addition, birds intoxicated by carbosulfan – vulnerable to predator attacks – were able to reach shelters, like forest reserves. Effects of pesticides over the agricultural matrix may propagate through forest fragments, affecting negatively its quality and aggravating the problem of habitat fragmentation, one of the main causes of the biological diversity erosion. These aspects are contrary to the use of carbosulfan and other products, which are up to 20 times less toxic than carbofuran, for the treatment of seeds or as gustative repellents.

The authors had concluded, if seeds treated with pesticides must receive a different color to prevent accidents with humans, the camouflaging method may be used for mitigating the mortality of birds in plantations, substituting rhodamine B (Almeida et al. 2010a).

Another study focusing on mitigation methods was realized consolidating two experiments, witch compares the environmental impacts associated with the use of carbofuran, carbosulfan and methiocarb-treated seeds, with the latter two carbamate compounds being considered as alternatives to carbofuran, and all coloured with Rhodamine B (Almeida & Almeida, in press). Methiocarb (Mesurol) also is a carbamate insecticide, causes vomiting and paralysis when ingested by birds, acting as a secondary chemical repellent (Calvi et al., 1976; Dolbeer, 1994).

The rice and wheat experimentation occurred in similar conditions of bird abundance, in the same geographical region, and using equals sowing method and carbofuran/carbosulfan treatments of the anterior study. Likewise, the data collect method and the analysis were the same. The experiments were done with 664 kg of seeds, sowed in 5.74 hectares. A comparison between the number of deaths consistent with ingesting seeds treated with carbamates was made with the treatments: in the first rice trial: i) carbofuran and

to the soil. In addition, camouflaged coating, made with the powder, presents an opaque surface and, for this reason, has less shine than seeds treated with rhodamine, being less conspicuous (Schmidt et al., 2004; Cuthill et al., 2005). Besides, it is possible that there wasn't search image for brown seeds, and in accordance with the optimal foraging theorem, greater energy would be required to consume and locate such seeds (Avery, 2002; Begon et al. 2006). However, the ingestion of small grits to help crush foods is a common aspect in the behavior of several bird Families (Sick, 1997). So, it is possible that brown-dyed seeds are less removed due to a set of factors linked to the camouflaging phenomenon like background match, avoiding well defined contours and color contrasts (Merilaita 2003, Frankel et al., 2004, Schmidt et al., 2004) and not only due to the aversion to the brown color, as tested by Hartley et al. (1999, 2000). They tried blue and brown with relative success at avoiding the consumption of poisoned grains by birds, suggesting such colors would cause aversion. The notable ingestion of red seeds suggests that this color, attributed by rhodamine B, is not aversive, but attractive (Schmidt et al., 2004; Cuthill et al., 2005), which is in contradiction to the findings of Avery & Mason (1997) and Nelms & Avery (1997). This color's spectral behavior, in the wavelengths visible by the birds, is similar to yellow and orange (Schmidt et al., 2004), which are contrasting and conspicuous and similar to beige. This may explain the high consumption of seeds treated with carbofuran without rhodamine B. Thus, whether the reddish hue from rhodamine B, or the beige color, coming from the syrup of carbofuran without rhodamine B, there is a higher probability of birds detecting and ingesting less

The replacement of carbofuran with carbosulfan also appeared to reduce mortality, but carbosulfan mortality is thought to have been underestimated because of the apparent movement of affected birds after exposure. Besides, the possible carbosulfan action as a gustative repellent was not checked and, in addition, birds intoxicated by carbosulfan – vulnerable to predator attacks – were able to reach shelters, like forest reserves. Effects of pesticides over the agricultural matrix may propagate through forest fragments, affecting negatively its quality and aggravating the problem of habitat fragmentation, one of the main causes of the biological diversity erosion. These aspects are contrary to the use of carbosulfan and other products, which are up to 20 times less toxic than carbofuran, for the

The authors had concluded, if seeds treated with pesticides must receive a different color to prevent accidents with humans, the camouflaging method may be used for mitigating the

Another study focusing on mitigation methods was realized consolidating two experiments, witch compares the environmental impacts associated with the use of carbofuran, carbosulfan and methiocarb-treated seeds, with the latter two carbamate compounds being considered as alternatives to carbofuran, and all coloured with Rhodamine B (Almeida & Almeida, in press). Methiocarb (Mesurol) also is a carbamate insecticide, causes vomiting and paralysis when ingested by birds, acting as a secondary chemical repellent (Calvi et al.,

The rice and wheat experimentation occurred in similar conditions of bird abundance, in the same geographical region, and using equals sowing method and carbofuran/carbosulfan treatments of the anterior study. Likewise, the data collect method and the analysis were the same. The experiments were done with 664 kg of seeds, sowed in 5.74 hectares. A comparison between the number of deaths consistent with ingesting seeds treated with carbamates was made with the treatments: in the first rice trial: i) carbofuran and

mortality of birds in plantations, substituting rhodamine B (Almeida et al. 2010a).

camouflaged seeds.

1976; Dolbeer, 1994).

treatment of seeds or as gustative repellents.

Rhodamine B, ii) carbosulfan and Rhodamine B; and in the second wheat trial: i) carbofuran and Rhodamine B; ii) carbosulfan and Rhodamine B; iii) carbofuran and Rhodamine B plus methiocarb. Methiocarb was added to the seeds, after they received treatment with carbofuran and Rhodamine B. The dose of methiocarb powder was equal to 1 kg for each 100 kg seeds.

The resulting mortality of this experiment mounted to three species, distributed into 314 birds, which 308 were Eared Doves deaths. In the first trial plots, where seeds treated with carbofuran were sown, 109 birds were found dead, and in those treated with carbosulfan, 40 were recovered. These results differed significantly, suggesting that a greater mortality was caused by carbofuran, and that the use of carbosulfan may lessen the impact of grain farming on wild birds. In turn, data clearly showed that carbosulfan use will still result in notable mortality. Further, some birds were noted as having been visibly poisoned by carbosulfan, yet managed to leave the test plot and (though disorientated) reach refuge outside the test area (ca 550 metres away). It was not possible to know if these poisoned birds recovered or died after escaping the experimental plot. Given these points, just like in the anterior experiment, it's necessary consider: i) the number of deaths recorded was not accurate, since poisoned birds may have left the test plot; ii) carbosulfan didn't act as a secondary repellent which interrupts consumption; iii) birds poisoned with carbosulfan had a greater tendency to reach the adjacent forest, where they may be preyed upon by forest species, therefore be hidden from farmers, researchers and hence, public opinion. These points raise questions regarding the principle that carbosulfan may not be used as a substitute for carbofuran. The findings reported here suggest that carbosulfan is probably not an effective alternative to carbofuran.

Fig. 8. The distribution of seeds in a plot of the removal experiment.

Camouflage of Seeds, a Control Method of the Bird Mortality in Grain Crops 373

of columns was modified in each parcel so that all treatments could bear the same influence

Trial 2. The differences in the permanence of wheat, corn and rice seeds with the following treatments were evaluated: i) natural, undyed seeds; ii) rhodamine B-treated seeds; ii) brown powder dye camouflaged seeds; iv) industrialized camouflage with liquid brown dye; v) seeds camouflaged with mid-blue powder dye (Figure 13). Permanence differences among treatment (colors) and botanical species were also evaluated in using twelve experimental parcels (four parcels per grain species). All the parcels were weeded and leveled for making the counting of smaller seeds (wheat and rice) more accurate. Because columns with either natural colors, blue or rhodamine B could be more attractive to birds, the order of the columns was changed in each parcel, exposing the camouflage treatments to

influences identical to the closeness to groups with attractive colors.

Fig. 9. Corn camouflaged in a plot of the removal experiment

removal of blue-colored seeds.

reliable mitigation method.

The following findings were obtained: i) the camouflaged seeds were less removed than seeds with rhodamine B and natural colors, noticing that the removing of powder dye camouflaged seeds, standed between 84.5% to 98% bellow of those with rhodamine B; ii) the camouflaging was more effective in the presence of irregularities and litter; iii) there was no

Regarding the seed camouflaging, the authors concluded that the method presents low operational and financial costs, does not cause suffering to birds and may be used to diminish bird´s mortality by carbofuran in wheat, corn and rice plantations. In concern of the blue seeds, the absolute absence consumption reinforces the theory that there is aversion to this color, according to Avery et al. (1999), Hartley et al. (1999, 2000), with the possible occurrence of aposematism (Joron, 2003) and neophobia (Thomas et al., 2004). Nevertheless, as the usage of blue-colored granular carbofuran had been prohibited because of the mortality of birds caused by the direct ingestion, this color probably should not represent a

of closeness to the control groups.

In the second assay, the possible repellent effects of methiocarb and carbosulfan were not statically proven. In the treatment with methiocarb, 62 birds died, while similar results were obtained using carbofuran, where 82 birds died. Although fewer birds died when carbosulfan was used, as in the previous trial and experiment, many birds visibly affected by carbosulfan escaped the test plot, making an accurate estimation of mortality difficult.

Although previous experiments have shown the relative efficacy of methiocarb as a secondary repellent to birds (Nelms & Avery 1997; Avery *et al.* 2001; Avery 2002), its use in association with carbofuran did not generate results showing it to be a mitigating factor in bird mortality, probably because carbofuran is an extremely toxic pesticide, needing only one treated seed to kill a small or medium sized bird (Almeida et al., 2010a). Thus the toxicity of carbofuran would overrun any of the potentially beneficial effects of methiocarb.

Finally, a third field study, performed in two trials (Almeida et al., 2010b) aimed at evaluating if camouflaged seeds would be less consumed by wild birds in comparison to commercial seeds coated with red-colored rhodamine B and blue seeds (Avery et al., 1999; Hartley et al., 1999; 2000). Seed removal experiments were performed in an area reserved for annual planting of 2.78 ha in southeast of Brazil, where, because of the frequent planting of corn and other cultures, a great deal of granivorous birds could be found at the site. Experimental parcels (1.5 x 1.5 m) were randomly distributed in the area circa 50 m from each other. Seeds from each treatment were disposed in columns over the ground approximately 11 cm apart (Figures 8, 9 and 10). Daily samplings were taken for six days after setup, checking the number of remaining seed in these periods.

Camouflages tested corresponded to the treatments created with the ingredients: liquid dye and powder dye, both colored brown and/or terracota. The brown-colored powder dye was shaded and thus adjusted by comparison to soil samples from the area. The camouflaged coating elicited by powder dye gave the seeds a dark brown, rugged and opaque surface.

The brown-colored liquid dye was a novel product which attributed to the seeds a smooth, opaque coating, with a shade slightly lighter than the soil in the experiment location. Acrylic glue was added to the dye to enhance adhesion and resistance to camouflaging. Dye and glue were applied to seed as an aqueous solution. Soil of the trials' site was tested as a substitute to artificial dyes and/or as an accessory camouflaging element, aiming for a higher coincidence in shades of camouflaging colors in relation to the soil.

Camouflages were applied onto seeds with either natural or purplish-red colors previously treated with rhodamine B dye, the product ordinarily and legally used in Brazil to distinguish pesticides-treated seeds.

To evaluate the effect of the search image (Begon et al., 2006) of birds for non-dyed natural grains in comparison to the other treatments, ordinary corn seeds were also used to mimic the situation wild birds find in harvest wastes. Finally, to evaluate the possible aposematic or neophobic effect of blue color, seeds were treated with mid-blue powder dye.

None of the tested treatments had pesticides. Variance analyses of the daily seed permanence in the trials were performed.

Trial 1. To evaluate camouflaged corn seed remaining, natural and rhodamine B-colored, twelve squares with seven rows of seeds each were distributed. Five types of brown camouflage treatments were tested, natural undyed corn and corn with rhodamine B only. The soil under five parcels was weeded and leveled to elicit studying the influence of irregularities and litter on seed removal. The yellow corn grain (natural) and rhodamine Btreated corn columns could be more attractive to the birds, possibly exposing columns close to groups one and two to higher pressure than those more distant. For that reason, the order

In the second assay, the possible repellent effects of methiocarb and carbosulfan were not statically proven. In the treatment with methiocarb, 62 birds died, while similar results were obtained using carbofuran, where 82 birds died. Although fewer birds died when carbosulfan was used, as in the previous trial and experiment, many birds visibly affected by carbosulfan escaped the test plot, making an accurate estimation of mortality difficult. Although previous experiments have shown the relative efficacy of methiocarb as a secondary repellent to birds (Nelms & Avery 1997; Avery *et al.* 2001; Avery 2002), its use in association with carbofuran did not generate results showing it to be a mitigating factor in bird mortality, probably because carbofuran is an extremely toxic pesticide, needing only one treated seed to kill a small or medium sized bird (Almeida et al., 2010a). Thus the toxicity of carbofuran would overrun any of the potentially beneficial effects of methiocarb. Finally, a third field study, performed in two trials (Almeida et al., 2010b) aimed at evaluating if camouflaged seeds would be less consumed by wild birds in comparison to commercial seeds coated with red-colored rhodamine B and blue seeds (Avery et al., 1999; Hartley et al., 1999; 2000). Seed removal experiments were performed in an area reserved for annual planting of 2.78 ha in southeast of Brazil, where, because of the frequent planting of corn and other cultures, a great deal of granivorous birds could be found at the site. Experimental parcels (1.5 x 1.5 m) were randomly distributed in the area circa 50 m from each other. Seeds from each treatment were disposed in columns over the ground approximately 11 cm apart (Figures 8, 9 and 10). Daily samplings were taken for six days

Camouflages tested corresponded to the treatments created with the ingredients: liquid dye and powder dye, both colored brown and/or terracota. The brown-colored powder dye was shaded and thus adjusted by comparison to soil samples from the area. The camouflaged coating elicited by powder dye gave the seeds a dark brown, rugged and opaque surface. The brown-colored liquid dye was a novel product which attributed to the seeds a smooth, opaque coating, with a shade slightly lighter than the soil in the experiment location. Acrylic glue was added to the dye to enhance adhesion and resistance to camouflaging. Dye and glue were applied to seed as an aqueous solution. Soil of the trials' site was tested as a substitute to artificial dyes and/or as an accessory camouflaging element, aiming for a

Camouflages were applied onto seeds with either natural or purplish-red colors previously treated with rhodamine B dye, the product ordinarily and legally used in Brazil to

To evaluate the effect of the search image (Begon et al., 2006) of birds for non-dyed natural grains in comparison to the other treatments, ordinary corn seeds were also used to mimic the situation wild birds find in harvest wastes. Finally, to evaluate the possible aposematic

None of the tested treatments had pesticides. Variance analyses of the daily seed

Trial 1. To evaluate camouflaged corn seed remaining, natural and rhodamine B-colored, twelve squares with seven rows of seeds each were distributed. Five types of brown camouflage treatments were tested, natural undyed corn and corn with rhodamine B only. The soil under five parcels was weeded and leveled to elicit studying the influence of irregularities and litter on seed removal. The yellow corn grain (natural) and rhodamine Btreated corn columns could be more attractive to the birds, possibly exposing columns close to groups one and two to higher pressure than those more distant. For that reason, the order

after setup, checking the number of remaining seed in these periods.

higher coincidence in shades of camouflaging colors in relation to the soil.

or neophobic effect of blue color, seeds were treated with mid-blue powder dye.

distinguish pesticides-treated seeds.

permanence in the trials were performed.

of columns was modified in each parcel so that all treatments could bear the same influence of closeness to the control groups.

Trial 2. The differences in the permanence of wheat, corn and rice seeds with the following treatments were evaluated: i) natural, undyed seeds; ii) rhodamine B-treated seeds; ii) brown powder dye camouflaged seeds; iv) industrialized camouflage with liquid brown dye; v) seeds camouflaged with mid-blue powder dye (Figure 13). Permanence differences among treatment (colors) and botanical species were also evaluated in using twelve experimental parcels (four parcels per grain species). All the parcels were weeded and leveled for making the counting of smaller seeds (wheat and rice) more accurate. Because columns with either natural colors, blue or rhodamine B could be more attractive to birds, the order of the columns was changed in each parcel, exposing the camouflage treatments to influences identical to the closeness to groups with attractive colors.

Fig. 9. Corn camouflaged in a plot of the removal experiment

The following findings were obtained: i) the camouflaged seeds were less removed than seeds with rhodamine B and natural colors, noticing that the removing of powder dye camouflaged seeds, standed between 84.5% to 98% bellow of those with rhodamine B; ii) the camouflaging was more effective in the presence of irregularities and litter; iii) there was no removal of blue-colored seeds.

Regarding the seed camouflaging, the authors concluded that the method presents low operational and financial costs, does not cause suffering to birds and may be used to diminish bird´s mortality by carbofuran in wheat, corn and rice plantations. In concern of the blue seeds, the absolute absence consumption reinforces the theory that there is aversion to this color, according to Avery et al. (1999), Hartley et al. (1999, 2000), with the possible occurrence of aposematism (Joron, 2003) and neophobia (Thomas et al., 2004). Nevertheless, as the usage of blue-colored granular carbofuran had been prohibited because of the mortality of birds caused by the direct ingestion, this color probably should not represent a reliable mitigation method.

Camouflage of Seeds, a Control Method of the Bird Mortality in Grain Crops 375

Fig. 11. Eared dove (*Zenaida auriculata*) killed by ingestion of wheat seeds treated with carbofuran. Eared dove were the most numerous casualties in the plantation experiments. Aware of the fact that some birds poisoned by carbosulfan escaped into the surrounding habitat before dying, such estimates need to consider that the mortality caused by carbosulfan was probably conservative and not accurate. Moreover, counting did not provide a full tally of secondary poisoning mortality rates, since predators left the area or those carcasses were

The estimative of the number of birds potentially poisoned on Brazilian farms are very worrying. Agrotoxins like carbofuran are used on a very large scale in Brazil, and improper use occurs throughout the agricultural landscape. Governmental control is very absent, and millions of hectares are devoted to rice, wheat, and corn production. Species such as the eared dove are abundant in some regions, and they may be both, victims and vectors, effectively passing the agrotoxin legacy up the food chain to predators (some of whom may

Fig. 12. Activity of predators removing poisoned bird, as evidenced by the pile of feathers.

removed by scavengers before being counted (as described by Mineau 2005).

be rare) as the poisoned doves are predated or scavenged.

Fig. 10. Domestic pigeons (*Columba livia*) feeding near to the plots of the removal experiment
