Synthesis of Noise Effects on Wildlife Populations

1. Synthesis of Noise Effects on Wildlife Populations Paul Kaseloo Department of Biology Virginia State University

2. Purpose • To create a review and literature database that could be used to review the effects of noise (particularly road noise) on wildlife • Covers animals (invertebrate and vertebrate) – greatest amount of information deals with birds and mammals

3. Background • It has been estimated (in part based on the estimates of the effects on birds) that 20% of the land area of the United States is ecologically affected by public roads (Forman, 2000; Cons. Biol. 14:31-35)

4. Questions • What is known about the response of birds to road noise? • What are the implications of these findings? • What future work could be considered to answer outstanding questions?

5. Effect Distance • The distance from the road up to the point where reduced density was recorded

6. Early work • Avoidance (i.e. reduced breeding density) by at least two grassland species (lapwing and black-tailed godwit) • Rural road (Effect distance ~ 500-600 m) with 50 vehicles/day • Highway (Effect distance ~ 1600-1800 m) with 54,000 vehicles/day (van der Zande et al., 1980; Biol. Cons. 18:299-321)

7. Woodland birds • A study of 43 bird species (in deciduous and coniferous forests) found reduced breeding densities of 26 species (60%) with effect distances that increase with the amount of traffic: 40–1500 m at 10,000 vehicles/day 70-2800 m at 60,000 vehicles/day (Reijnen et al., 1995; J. Appl. Ecol. 32:187-202)

8. Woodland birds (cont…) • In a multi-year study 17 of 23 species studied showed a decrease in breeding density near the road in at least one year (40-52,000 vehicles/day) • This effect was reduced (only 4 species) in years with high population density

9. Woodland birds • High overall population levels will lead to underestimation of the quality of the habitat (i.e. would not see the effect in years of high density) (Reijnen and Foppen, 1995; J. Appl. Ecol. 32:481-491)

10. (Reijnen et al., 1997; Biodiv. Cons. 6:567-581)

11. Grassland Birds • Similar to the earlier study 7 of 12 species studied showed a reduction in breeding density adjacent to roads • The effect distances varied with species and increased with traffic density

12. Grassland birds (cont…) • Effect distances ranged between: • 20-1700 m at 5,000 vehicles/day • 65-3530 m at 50,000 vehicles/day (Reijnen et al., 1996; Biol. Cons. 75:255-260)

13. Grassland Birds (cont…) • Five years of data on birds (mainly based on two species - bobolinks and meadowlarks) near Boston found: • Effect distances: 3,000-8,000 vehicles/day – none 8,000-15,000 vehicles/day – 400 m (breeding only) 15,000-30,000 vehicles/day – 700 m ≥30,000 vehicles/day – 1200 m (Forman et al., 2002; Environ. Manage. 29:782-800)

14. Previous Recommendations • Sound levels above about 50 dB(A) • Estimate effect distances of about 1000 m (Reijnen et al., 1997; Biodiv. Cons. 6:567-581)

15. Other Possible Causes • Visual disturbance • Air pollution • Microclimatic effects • Road kill • Increased attraction of predators • Unlikely to have an effect at the distances reported (Forman et al., 2002; Environ. Manage. 29:782-800)

16. Other Considerations • Not all species appear sensitive (e.g. Study in Spain estimated ~ 15% of breeding bird species sensitive, although total density did not differ at different levels of traffic) (Peris and Pescador, 2004; Appl. Acoustics 65:357-366) • Some species become more common near roads (ecotonal environment) (Michael et al., 1976; Proc. 1st Nat. Symp. Environ. Conc.)(Ferris, 1979; J. Wildl. Manage. 43:421-427) (Adams and Geis, 1981; FHWA/RD-81/067)

17. Other Considerations • Some species breed well even in noisy environments (e.g. California gnatcatchers) (Awbrey et al., 1995; Inter-noise 65:971-974)

18. Other Considerations • Rights-of-way have been shown to provide breeding habitat for some species (e.g. pheasants, ducks, passerines) – particularly in areas of disturbance such as agricultural areas (Warner and Joselyn, 1986; J. Wildl. Manage. 50:525-532) (Oetting and Cassel, 1971; J. Wildl. Manage. 35:774-781) (Voorhees and Cassel, 1980; J. Wildl. Manage. 44:155-163) (Laursen, 1981; Biol. Cons. 20:59-68) (Warner, 1992; Biol. Cons. 59:1-7)

19. Mechanisms • It has been found that higher-pitched frequencies in bird songs may make species less susceptible to noise effects from roads implying masking as a causative mechanism (Rheindt 2003; J. für Ornith. 144:295-306)

20. Mechanisms • Birds in noisier urban environments also increased amplitude of songs when background noise increased (Brumm, 2004; J. Anim. Ecol. 73:434-440)

21. Important Questions • Is noise alone sufficient to cause the effect seen? • It has been established that it is not the presence of a road, but the level of traffic that influences the densities of birds, presumably due to noise because of the distances involved • Will mitigation of noise alone be sufficient to change the response?

22. (Reijnen et al., 1997; Biodiv. Cons. 6:567-581)

23. Future Research • Can noise (as opposed to noise with associated traffic) cause the same effect? (i.e. can mitigation of noise be expected to reduce the effect zone) • Will reduction in noise lead to a return of affected species? (How long until this response is seen?)

24. Future Research • What are the proximate effects of noise on birds? • Masking of vocalization? • Physiological changes? • Locomotor activity? • Behavioral patterns?

25. Future Research • Can we see areas where noise mitigation (for other purposes) has altered species composition compared to areas without mitigation?

26. Acknowledgements • Undergraduate research assistant Katherine Tyson • Paul Garrett @ FHWA for support and advice • Funded through FHWA cooperative agreement DTFH61-03-H-00123

27. Questions?