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

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

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)

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?

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

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

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 m at 60,000 vehicles/day (Reijnen et al., 1995; J. Appl. Ecol. 32: )

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

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: )

(Reijnen et al., 1997; Biodiv. Cons. 6: )

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

Grassland birds (cont…) Effect distances ranged between: m at 5,000 vehicles/day m at 50,000 vehicles/day (Reijnen et al., 1996; Biol. Cons. 75: )

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: )

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

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: )

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: ) Some species become more common near roads (ecotonal environment) (Michael et al., 1976; Proc. 1 st Nat. Symp. Environ. Conc.) (Ferris, 1979; J. Wildl. Manage. 43: ) (Adams and Geis, 1981; FHWA/RD-81/067)

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

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: ) (Oetting and Cassel, 1971; J. Wildl. Manage. 35: ) (Voorhees and Cassel, 1980; J. Wildl. Manage. 44: ) (Laursen, 1981; Biol. Cons. 20:59-68) (Warner, 1992; Biol. Cons. 59:1-7)

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: )

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

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?

(Reijnen et al., 1997; Biodiv. Cons. 6: )

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?)

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

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

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

Questions?