Comparison of Soundscapes in Disturbed and Undisturbed Environments. Kathryn Ganter. Dominica Study Abroad Dr. Woolley and Dr.

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1 Comparison of Soundscapes in Disturbed and Undisturbed Environments Kathryn Ganter Dominica Study Abroad 2015 Dr. Woolley and Dr. Lacher Texas A&M University Highlighting indicates items, species names, and terminology that would have been looked up if the internet was working.

2 Abstract Soundscape ecology is a field that is increasingly being used to measure the health of an environment. This project compared the dawn and dusk soundscapes of an undisturbed area with that of a disturbed area. The two environments were shown to have vastly different soundscapes, suggesting that the human disturbance has had a significant effect on the ecosystem. Introduction A soundscape is the combination of all sounds from the surrounding environment. It includes the sounds generated by humans and animals, and nonbiological ambience such as rainfall or rivers. Humans affect the soundscape of an area not only through man-made sounds such as traffic but also through altering or destroying natural habitats. This is referred to as disturbing the environment. An environment is considered disturbed if it has undergone intense stress that significantly affected the ecosystem. The disturbed environment observed, Archbold Tropical Research and Education Center (Springfield) on the island of Dominica, was once a plantation. Its original flora was replaced with crops and the area around the facilities is continuously maintained. This type of disturbance can seriously alter an ecosystem by removing plants and leaf litter that serve as natural environments. The goal of this data collection was to examine the effect that human activities and disruption have on the soundscapes heard at dawn and dusk. To do this, the soundscape of Archbold was compared with that of an undisturbed area,

3 Emerald Pool. Emerald Pool is an area of primary wet rainforest in Morne Trois Pitons National Park. Materials and Methods Soundscapes were recorded with a Marantz Professional PMD661 Compact Digital Recorder and a Shure BG 4.0 Microphone. The morning soundscapes for both locations were recorded between 6:00 and 7:00, while the evening soundscapes were recorded between 20:00 and 21:00. Sounds were then manipulated with different computer programs. They were first converted to FLAC files using Audacity. Those files were then clipped and analyzed using Raven software. The Raven interface, shown in Figures 1-4, displays a graph of sound amplitude (how loud the sound is on the recording) and a spectrograph (a graph of the different frequencies recorded.) Isolation of different impressions on the spectrographs in Raven made it possible to identify songs and calls of the different species that composed the soundscape. The soundscapes were then compared qualitatively.

4 Results Figure 1 - Emerald Pool (Morning) 1. Sharp, rapidly descending call a. 9-7 khz b. accompanying harmonic khz c. continuous droning from 9-16 khz 2. Suspected mole crickets (continuous droning, 6-7 khz) 3. Setophaga plumbea (Plumbeous Warbler) (erratic call, khz) 4. Myadestes genibarbis (Mountain Whistler) (shrill whistling, 2-4 khz) 5. Distant water sounds (0-1 khz, throughout)

5 Figure 2 - Springfield (Morning) 1. Rain (continuous, 8-16 khz) 2. Chirping of birds (vertical lines, 6-12 khz) 3. Eleutherodactylus martinicensis (Tink frogs) (horizontal bands, 2 and 4 khz) 4. Cooing - Zenaida Doves (spots around.5-1 khz)

6 Figure 3 - Emerald Pool (Evening) 1. Katydids (pairs of vertical lines 9-13kHz) 2. Mole crickets (continuous droning, 6.5 khz) 3. Tinking (groups of 4-5; obvious lines in amplitude) 3a. 11 khz 3b. 5.5 khz 4. Eleutherodactylus martinicensis (Tink frogs) (2-4 khz) 5. Distant water sounds (continuous, 0-1 khz)

7 Figure 4 - Springfield (Evening) 1. Rain (continuous, 8-16 khz) 2. Suspected mole crickets (continuous droning 6.5 khz) 3. Suspected crickets (continuous droning 5 khz) 4. Tinking (groups of 4-5, 3 khz) 5. Eleutherodactylus martinicensis (Tink frogs) (2-4 khz) Discussion The Emerald Pool morning soundscape is abundant in loud, continuous birdcalls. It also had the sound of mole crickets, and what is believed to be an insect noise that could not be identified. The sound consisted of a sharp, rapidly descending call from 9-7 khz, with a much higher harmony accompanying it at 14-

8 16.5 khz. This frequency is much higher that any other recorded noise, so it is unlikely to be a birdcall. It is suspected to be an insect because there is a continuous droning from 9-16 khz throughout the recording except when the sharp call is heard. This suggests that the same animal is making the droning and the call. It is unlikely that a frog or bird could make such a continuous sound, as both of these organisms would need to draw breath. While the Emerald Pool morning soundscape was predominately birds, the Springfield morning soundscape was dominated by frogs. Some bird sounds were heard, but nothing like the magnitude or diversity seen at Emerald Pool. These differences were just as significant in the night recordings. The evening Emerald Pool soundscape featured abundant katydids, crickets, and an unidentified, almost metallic tinking noise unlike that of a tink frog. This may have been another species of katydid or cricket, or possibly a variation of the tink frog s call. Close inspection of the spectrograph shows that the tinking may be related to the katydid sounds, because it is seen almost exclusively in between two katydid calls (Figure 3.) The evening Springfield soundscape, on the other hand, had these same cricket sounds and metallic tinks, but the vast majority of the sounds observed came from the tink frog. Overall, Springfield had more frogs and Emerald Pool had more insects and birds. This may be because the primary growth of Emerald Pool serves as a habitat for many nesting birds. Emerald Pool also retains its leaf litter, which is a known habitat for many insects. The abundance of frogs at Springfield could be caused by a

9 variety of different factors. Because there are fewer birds, there could be less of a competition for insect meals. Because frogs do not seem to be as strongly affected by the loss of trees, the decreased competition would cause frog populations to increase. Another possible factor is the increased organic material in water sources around Springfield. The water at Emerald Pool runs mostly over rocks, while the water at Springfield has more vegetation and consists of runoff water from pipes. This increase in organic matter may be more suitable to the frogs themselves, or may attract aquatic insects that the frogs prefer to feed on. This subject has great potential in this area. Several interesting patterns were seen that we were not able to investigate due to time constraints. A longer study or a study over more environments would be very interesting to see, and could give interesting insight into the ecosystems of the island. References Pijanowski, BC, Villanueva-Rivers, LJ, Dumyahn, SL, Farina, A, Krause, BL, Napoletano, BM, Gage, ST, Pieretti, N Soundscape ecology: the science of sound in the landscape. BioScience 61: Acknowledgements I would like to thank Texas A&M University, Andrew Evans for telling me about sound ecology after my frogs failed me, and Dr. Lacher and Dr. Woolley for the mentorship, helping me identify animal noises, driving me to Emerald Pool at five in the morning, and putting up with all of us.

Comparison of Calls of the Rufous-Throated Solitaire in Different Locations on Dominica. By: Kiersten Wiley. Texas A&M University

Comparison of Calls of the Rufous-Throated Solitaire in Different Locations on Dominica By: Kiersten Wiley Texas A&M University Study Abroad Dominica 2012 Dr. Tom Lacher and Dr. Jim Woolley May 22-June