Mikolajczak, J. et.al. Preliminary Studies, Growing Geese in Proximity of Wind Turbines
Preliminary studies on the reaction of growing gees to the proximity of wind turbines
J. Mikolajczak, S. Borowski, J. Marc-Pienkowska, G. Odrowaz-Sypniewska, Z. Bernacki, J. Siodmiak, P. Szterk published in the Polish Journal of Veterinary Sciences vol 16, No 4, (2013) 679-686
Key findings include:
- “cortisol concentration increased with the residence time in the vicinity of the wind turbines”
- “Animals kept near the wind turbine had about 10 percent lower body weight than those kept at a distance of 500m from the turbine”
- “The lower cortisol concentration in animals kept at a distance of 500m may indicate that this distance is safer for animals but still not safe enough”
Wind farms produce electricity without causing air pollution and environmental degradation. Unfortunately, wind turbines are a source of infrasound, which may cause a number of physiological effects, such as an increase in cortisol and catecholamine secretion. The impact of infrasound noise, emitted by wind turbines, on the health of geese and other farm animals has not previously been evaluated. Therefore, the aim of this study was to determine the effect of noise, generated by wind turbines, on the stress parameters (cortisol) and the weight gain of geese kept in surrounding areas.
The study consisted of 40 individuals of 5-week-old domestic geese Anser anser f domestica, divided into 2 equal groups. The first experimental gaggle (I) remained within 50m from turbine and the second one (II) within 500m. During the 12 weeks of the study, noise measurements were also taken. Weight gain and concentration of cortisol in blood were assessed and significant differences in both cases were found. Geese from gaggle I gained less weight and had a higher concentration of cortisol in blood, compared to individuals from gaggle II. Lower activity and some disturbing changes in behaviour of animals from group I were noted.
Results from the study suggest a negative effect of the immediate vicinity of a wind turbine on the stress parameters of geese and their productivity.
Sound waves are divided into infrasound, audible sounds and ultrasounds (Pawlas 2009). Infrasound is a sound or noise with a frequency spectrum ranging from 1 to 20 Hz (Augustynska 2009), and is perceived not as a “normal” tone, but rather as a pounding and the feeling of “tightness” in the ears (Pawlas 2009).
Continuous sounds (both audible and infrasound noise) may be produced by wind turbines. The level of noise emitted by wind turbines, ranges from 100-107 dB and decreases as the distance from the turbine increases (Pawlas 2009).
Currently, there is no European and international legislation concerning the exposure limit values for infrasound (Augustynska 2009). The results of animal studies suggest considerable nuisance and harmfulness of infrasound, and therefore indicate the need to determine the safe level of noise.
The effect of infrasound on animals under laboratory conditions, has often been studied (Nekhoroshev and Glinchikov 1992, Bohne and Harding 2000). During such studies the adverse effects of infrasound were noted in animals such as mice, rates, guinea pigs, chinchillas, dogs, monkeys and other mammals. Changes maybe observed in the cardiovascular system (narrowing of arteries and coronary vessels (Alekseev 1985), in the brain (Nekhoroshev and Glinchikov 1992) and in the lungs (thickening of alveoli and filling of the pulmonary acinus with erythrocytes, the partial destruction of the acinus and the disruption of blood vessel walls) (Svidovyi and Glinchikov 1987). Infrasound with a very high intensity may cause serious damage to ear structures (Johnson 1980). Continuous exposure may cause significant changes in comparison to intermittent exposure. In chinchillas constantly exposed to infrasound at a frequency of 0.5Hz and a level of 95 cB, damage to hearing may occur after 2 days up to 432 days of exposure (Bohne and Harding 2000). In humans exposed to infrasound some psychological and physiological changes such as fatigue and wakefulness disorders, related to changes in the central nervous system, have been reported (Landstrom et al. 1983).
Under natural conditions, infrasound generated by wind turbines reduces species diversity during nesting (Francis et al. 2009) and may have negative effects on the behaviour, communication skills, health and survival ability of birds (Barber et al. 2010), and also on squirrels’ ability to recognise predators (Rabin et al. 2006). In the case of animals living fenced in, held without the possibility of free movement, noise can lead to an increasing level of stress (Flydal et al. 2004). In domestic animals, such as sheep and horses, the noise form wind turbines at a level of 60-75 dB may cause acceleration of breath, rapid heart rate, increased alertness and reduced grazing time (Ames and Arehart 1972). Increased cortisol secretion in sheep was observed as a response to stress cause by exposure to the noise emitted during the shearing procedure (Hargreaves and Hutson 1990). However, more research showing the impact of noise emitted by wind turbines on farm animals is needed.
Glucocorticoids (GCs): cortisol and corticosterone, are the front-line hormones in overcoming stressful situation (Palme et al. 2005). Although corticosterone is considered to be the dominant avian glucocorticoid and is well known as a stress hormone in birds (Koren et al. 2012), there are some papers demonstrating that birds also produce cortisol (Walsh et al. 1985, Schmidt and Some 2008, Sohail et al. 2010, Swathi et al. 2012, Jadhaw et al. 2013). We, therefore, examined the changes of cortisol concentration in blood of geese as a response to the possible stress caused by infrasound generated by a wind turbines.
Discussion – Cortisol
48 hours after transportation and placement of the birds at the sites, located at a distance of 50 and 500 metres from the wind turbine, the cortisol concentration in the blood of geese from group I was significantly higher than the concentration of cortisol in animals from group II. In addition, the geese in gaggle I exhibited reduced adaptability and their behaviour (reduced physical activity and feed intake) indicated exposure to stress.
In the 10th week the average concentration of cortisol in the blood of birds from group I was significantly higher than the concentration of cortisol in geese from group II. Also in the 17th week of rearing the concentration of cortisol in the blood of birds kept in the immediate vicinity of the wind turbine was noticeably higher than in the geese that lived at a distance of 500m from the turbine. The differences in cortisol concentration recorded during all three measurements, between the two groups of birds, were found to be highly statistically significant (p<0.001).
After 48 hours, geese from group I had twice the cortisol concentration in blood compared to group II. In the 10 week of the experiment, the concentration of cortisol in the blood from group I was 3.5 times higher than the concentration of cortisol in the blood from group II. In the 17th week, the cortisol concentration in the blood of birds from group I, compared to geese from the group II, was 2.7 times higher, so it is possible to assure that even though there are some significant differences in the cortisol concentration in the blood of animals from both groups, there is a tendency which suggests that geese may become accustomed to a stressor.
In the 5th week, males from gaggle I had a higher cortisol concentration in blood than female geese, in gaggle II the result was the opposite. In the 10th week, a higher concentration of cortisol in the blood of females from group I was noted, but in group II the result was opposite. At the end of the study in both gaggles females had a higher concentration of cortisol in blood than males, however, the difference was not sufficiently significant to claim that gender influences sensitivity to infrasound.
Moreover, the concentration of cortisol in the blood of geese increased with the time of exposure to the immediate vicinity of the wind plant.
All three successive measurements of cortisol concentration showed a higher concentration of “stress hormones” in birds kept at a distance of 50m from the turbine. The lower cortisol concentration in animals kept at a distance of 500m may indicate that this distance is safer for animals but still not safe enough, as mentioned below.
In birds, due to their endocrine dissimilarity, the corticosterone concentration during the stress response is commonly tested, and there are few publications on the change in the cortisol concentration in the blood of birds that are influenced by a stressor. Sohail et al. (2010) examined the impact of cyclic heat stress on serum cortisol concentration in broilers. Tokarzewski et al. (2006) studied the impact of the stress caused by transportation on the changes in the cortisol concentration in broiler blood. In the studies mentioned above, the results for control groups were as follows: 1.04 ng/mL (mean) (Sohail et al. 2010) and 1.55 ng/mL (mean) (Tokarzewski et al 2006), whereas in the experimental groups the results were: 1.91 ng/mL (mean) and 9.26 ng/mL (mean), respectively. In the present study, all results of the cortisol concentration were higher than the control values outlined above. The concentration of cortisol, determined in both gaggles, in every week of rearing (except for the concentration of cortisol in geese from group II in the 5th week), was also higher than concentrations of “stress hormones” obtained in the experimental groups by Tokarzewski et al. (2006) and Sohail et al. (2010. This information suggests that infrasound noise may be a very serious source of stress. In addition, it was noted that the cortisol concentration in the animals from group II was higher than the control concentration, which may therefore suggest that the distance of 500m from the turbine is still not a safe distance.
The reaction of the birds confirmed that geese have a sensitive sense of hearing and are responding to both audible sounds and infrasound.
Furthermore, a change in the animals’ behaviour was observed. Birds of group I, for the most part, remained in a compact group and showed less physical activity, while individuals from gaggle II moved freely. This change is likely to result from the exposure of the animals to chronic stress and may be associated with a higher concentration of cortisol, as was shown for birds from group I.
The literature review indicates that any stress, particularly mental, is accompanied by an excessive secretion of the adrenocorticotropic hormone (De Jong et al. 2001).
Discussion – Body Weight
In the 5th week, the body weights of birds from both groups were similar. In the 10th week, the average body weight of animals in group I was lower than the mean weight of individuals from gaggle II. Seven weeks later, the difference was even greater and was statistically significant (p<0.05). The mean body weight of both groups of animals, in 10 weeks of rearing, was lower than in the studies of Biesiada-Drzazga et al. (2006). Depending on the experimental group, the authors reported that the male’s body weight was from 5.29 to 5.61 kg and for females from 4.88 to 5.11.
In the 17th week, the body weight of geese from group I was much lower, but achieved weights in both groups were satisfactory and high than those found in the literature. During 17 weeks of rearing, Klos et al. (2010) obtained a weight of 5.74 – 6.00 kg for males and from 5.18kg to 5.38kg for females. Similarly, Lukaszewics et al. (2008) reported lower body weights – 7.09kg for males to 6.30kg for females. Moreover, in our experiment, sexual dimorphism was observed. The greatest differences in body weight between the sexes were found in the 17th week of rearing.
At the end of the study, the differences in the body weights between birds from both groups were found to be statistically significant (p<0.05). Animals kept near the wind turbine had about 10 percent lower body weight than those kept at a distance of 500m from the turbine. The lower body weight of group I was caused by reduced feed intake. Animals ate less willingly, which could have resulted from the stress caused by infrasound noise emitted by the wind turbine.
To sum up, the results of measuring noise generated by the wind turbine are in accordance with the results obtained by other research (van der Berg 2004). When the distance from the turbine increased, the intensity of infrasound decreased greatly, and at a distance of 1000m the intensity was 40 dB. Geese from the gaggle which was kept at a distance of 50m from the turbine, grew slower, gained less body weight (by 10%) and had a higher concentration of cortisol in blood, compared to birds reared 500 meters away from the wind plant. It was also noted that even the distance of 500 meters cannot be considered a safe one; this was confirmed by the results of infrasound measurement and cortisol concentration in blood, which exceeded the control values.
In addition, cortisol concentration increased with the residence time in the vicinity of the wind turbines. Differences in both weight and cortisol concentration were proven to be statistically significant. The cortisol concentration in both groups, which was higher than the concentration in the control groups, could have resulted from stress caused by the noise generated by the wind plant. Stress may have caused the disturbing changes in behaviour.
The results indicate the negative impact of the immediate vicinity of wind turbines on feed consumption, weight gain and cortisol concentration in blood. Nevertheless, further studies, with a larger number of animals and with a variety of distances, are needed, so that the safe distance appropriate for keeping animals can be determined.