Habitat effects on bird surveys:  a simultaneous experiment using Point Count and active Audio Recording in a Mediterranean protected area

Gaia Porporato; Lorenzo Gordigiani; Matthias Gabriel Berger; Francesco Ferretti; Flavio Monti

doi:10.30456/avo.30985

Authors

Gaia Porporato University of Siena , Bielefeld University https://orcid.org/0009-0005-2793-9696
Lorenzo Gordigiani National Biodiversity Future enter, Palermo, 90133, Italy https://orcid.org/0009-0009-3695-8695
Matthias Gabriel Berger University of Siena https://orcid.org/0009-0000-6552-5439
Francesco Ferretti University of Siena
Flavio Monti CNR-IRET https://orcid.org/0000-0001-8835-1021

DOI:

https://doi.org/10.30456/avo.30985

Keywords:

avifauna, bird monitoring, habitat, Italy, acoustic analysis, pinewood

Abstract

Habitat structure can affect species detectability and the performance of bird survey meth-ods, particularly in heterogeneous habitats, as variation in vegetation complexity can affect both visual detection and sound attenuation. However, a clear understanding of how hab-itat structure interacts with survey methodology to shape detection probability remains limited, especially in structurally diverse ecosystems such as the Mediterranean. To evaluate this, we conducted a simultaneous count comparing two survey methods, Point Count (PC) and active Audio Recording (AR), to assess their effectiveness in measuring spatial variation in bird species richness across three habitat types with different vegetation typologies: pine-wood, ecotone/open habitat and sclerophyllous forest, within a protected area in central coastal Italy during the 2021 breeding season (May-June). We hypothesized that (i) PC and AR would differ in detected bird species richness, and (ii) this performance could be influ-enced by habitat type, resulting in species richness varying between methods depending on habitat structure. We surveyed 37 sites using both methods simultaneously, with two replicas per site, totaling 74 sampling units. Species richness varied with habitat type, being highest in ecotone and open habitat and lower in pinewood and sclerophyllous forest, a pat-tern consistent across survey methods. Non-vocalizing birds, detected exclusively through PC, affected method performance only at the habitat level, with no overall effect across all sampling points combined. With the applied sampling effort, both methods reliably reflect-ed spatial variation in species richness, confirming that AR can serve as an effective tool for assessing relative bird diversity across habitats. Moreover, this simultaneous experimental approach offers practical guidance for future bird monitoring programs, particularly for bio-diversity assessments in heterogeneous habitats.

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References

Alldredge MW, Simons TR, Pollock KH (2007). Factors affecting aural detections of songbirds. Ecological Applications 17:948-955.

Arrigoni PV (2003). The vascular flora of the Maremma Regional Park (Tuscany, central Italy). Webbia 58:151-240.

Brotons L, Herrando S, Sirami C, Kati V, Díaz M (2018). Mediterranean Forest Bird Communities and the Role of Landscape Heterogeneity in Space and Time. Ecol. Conserv. For. Birds 9:318-349.

Buckland ST, Rexstad EA, Marques TA, Oedekoven CS (2015). Distance sampling: methods and applications (Vol. 431), New York, Springer.

Canterbury GE, Martin TE, Petit DR, Petit LJ, Bradford DF (2000). Bird communities and habitat as ecological indicators of forest condition in regional monitoring. Conservation Biology 14:544-558.

Celis-Murillo A, Deppe JL, Ward MP (2012). Effectiveness and utility of acoustic recordings for surveying tropical birds. Journal of Field Ornithology 83:166-179.

Celis-Murillo A, Deppe JL, Allen MF (2009). Using soundscape recordings to estimate bird species abundance, richness, and composition. Journal of Field Ornithology 80:64-78.

Darras K, Batáry P, Furnas B, Celis-Murillo A, Van Wilgenburg SL, Mulyani YA, Tscharntke T, (2018). Comparing the sampling performance of sound recorders versus point counts in bird surveys: A meta-analysis. Journal of Applied Ecology 55(6):2575-2586.

Díaz L, (2006). Influences of forest type and forest structure on bird communities in oak and pine woodlands in Spain. Forest ecology and management 223(1-3):54-65.

Dudley N, Belokurov A, Borodin O, Higgins-Zogib L, Hockings MT, Lacerda L, Stolton S (2004). Are protected areas working? An analysis of forest protected areas by WWF. WWF International.

Farina A, Lattanzi E, Malavasi R, Pieretti N, Piccioli L (2011). Avian soundscapes and cognitive landscapes: theory, application and ecological perspectives. Landscape Ecology 26:1257-1267.

Ferretti F, Lazzeri L, Fattorini N (2023). A test of motion-sensitive cameras to index ungulate densities: group size matters. The Journal of Wildlife Management 87(3):e22356.

Garcia-Moreno J, Harrison IJ, Dudgeon D, Clausnitzer V, Darwall W, Farrell T, Savy C, Tockner K., Tubbs N (2014). Sustaining freshwater biodiversity in the Anthropocene. Sustaining Freshwater Biodiversity in the Anthropocene. In: Bhaduri A, Bogardi J, Leentvaar J, Marx S, (eds) The Global Water System in the Anthropocene. Springer Water. Springer, Cham. [https://doi.org/10.1007/978-3-319-07548-8_17](https://www.google.com/search?q=https://doi.org/10.1007/978-3-319-07548-8_17&utm_source=gemini)

Giovacchini P (2006). Uccelli. In: Checklist della fauna del Parco Regionale della Maremma. Plantamura G, Manganelli G, (eds). Ente Parco Regionale della Maremma, Alberese (GR).

Giovacchini P (2019). The Birds of the Maremma Regional Park and adjacent areas (Grosseto, Tuscany, Italy). Rivista Italiana di Ornitologia 89:7-99.

Hansen IJK, Otter KA, Van Oort H, Holschuh CI (2005). Communication breakdown? Habitat influences on black-capped chickadee dawn choruses. Acta Ethologica 8:111-120.

Haselmayer J, Quinn JS (2000). A comparison of point counts and sound recording as bird survey methods in Amazonian southeast Peru. The Condor 102(4):887-893.

Herrando S, Brotons L (2002). Forest bird diversity in mediterranean areas affected by wildfires: a multiscale approach. Ecography 25:161-172

Hoefer S, McKnight DT, Allen-Ankins S, Nordberg EJ, Schwarzkopf L (2023). Passive acoustic monitoring in terrestrial vertebrates: a review. Bioacoustics 32(5):506-531.

Hutto RL, Stutzman RJ (2009). Humans versus autonomous recording units: A comparison of point-count results. Journal of Field Ornithology 80(4):387-398.

Kahl S, Wood CM, Eibl M, Klinck H (2021). BirdNET: A deep learning solution for avian diversity monitoring. Ecological Informatics 61:101236.

Katsimanis N, Dretakis M, Akriotis T, Mylonas M (2006). Breeding bird assemblages of eastern Mediterranean shrublands: composition, organisation and patterns of diversity. Journal of Ornithology 147:419-427.

Klingbeil BT, Willig MR (2015). Bird biodiversity assessments in temperate forest: the value of point count versus acoustic monitoring protocols. PeerJ 3:e973.

Melin M, Hinsley SA, Broughton RK et al (2018). Living on the edge: utilising lidar data to assess the importance of vegetation structure for avian diversity in fragmented woodlands and their edges. Landscape Ecol 33:895-910. [https://doi.org/10.1007/s10980-018-0639-7](https://www.google.com/search?q=https://doi.org/10.1007/s10980-018-0639-7&utm_source=gemini)

Melini D, Agrillo E, Ferretti F, Tonelli L (2019). Piano di Gestione della ZSC/ZPS IT51A0016 Monti dell’Uccellina. Ente Parco Regionale della Maremma, Prot. n. 0002262 del 07-10-201.

Miller JR, Cale P (2000). Behavioral mechanisms and habitat use by birds in a fragmented agricultural landscape. Ecological Applications 10(6):1732-1748.

Monti F (2012). Waterbirds community composition and richness at the Ombrone river’s mouth (Tuscany, GR). Atti del Museo di Storia Naturale della Maremma 23:49-55.

Monti F, Ferretti F, Fattorini N (2024). Intrinsic and extrinsic factors modulating vigilance and foraging in two gregarious foragers. Behavioral Ecology 35(1):arad114.

Monti F, Ancillotto L, Viviano A, Mggioni M, Dondina O, Lipparelli T, Mori E (2026). Repurposing Bird Bycatch From Camera Traps in Urban Landscapes: A Correlate of Avian and Mammalian Richness?. Journal of Zoology 1-9. [https://doi.org/10.1111/jzo.70145](https://doi.org/10.1111/jzo.70145?utm_source=gemini).

Nikolov SC, Demerdzhiev DA, Popgeorgiev GS, Plachiyski DG (2011). Bird community patterns in sub-Mediterranean pastures: the effects of shrub cover and grazing intensity. Animal Biodiversity and Conservation 34(1):11-21.

Orlando G, Varesio A, Chamberlain D (2021). Field evaluation for playback surveys: species-specific detection probabilities and distance estimation errors in a nocturnal bird community. Bird Study 68(1):78-87

Petty SJ, Avery MI (1990). Forest bird communities. Forestry Commission Occasional Paper 26:1-110.

Pezzo F (2012). The breeding Bird Community of the “Granducale Pinewood of Alberese” (Tuscany). Composition, Structure and Management Implications for Conservation. Atti del Museo di Storia Naturale della Maremma 23:91-101.

Porporato G (2024). Point Count vs. Audio Recording for monitoring bird communities: a comparison in a Mediterranean protected area. MsC thesis, University of Siena.

Ralph CJ, Droege S, Sauer JR (1995). Managing and monitoring birds using point counts: standards and applications. In: Ralph CJ, Sauer JR, Droege S (eds). Monitoring bird populations by point counts. Gen. Tech. Rep. PSW-GTR-149. Albany, CA: US Department of Agriculture, Forest Service, Pacific Southwest Research Station: p.161-168, 149.