Fungsi Vokalisasi Wiwik Kelabu (Cacomantis merulinus) dan Respons Burung Inang Terhadap Acoustic Playback Wiwik Kelabu

Abstract

Burung menggunakan vokalisasi untuk berkomunikasi. Berdasarkan studi akustik, vokalisasi burung terbagi menjadi menjadi dua yaitu suara panggilan (call) dan suara kicauan (song). Kelompok burung kedasi atau cuckoo dari famili Cuculidae melakukan perilaku berbiak yang unik yaitu dengan brood parasitism. Salah satu spesies burung kedasi adalah wiwik kelabu (Cacomantis merulinus) yang menjadi parasit bagi sarang dari banyak spesies burung dan kurang diteliti karena sulit diamati. Metode acoustic playback cocok digunakan untuk meneliti wiwik kelabu dengan memancing individu ke suatu lokasi kemudian diamati respons perilakunya. Penelitian ini bertujuan 1) mengidentifikasi teritori wiwik kelabu, 2) mengidentifikasi sebaran burung inang, 3) mendeskripsikan perilaku dan menduga fungsi vokalisasi wiwik kelabu, dan 4) menguji respons burung inang terhadap suara playback wiwik kelabu. Penelitian dilaksanakan di Kampus IPB Dramaga (267 Ha) pada bulan Maret-Agustus 2024. Secara umum wilayah penelitian terletak di daerah tropis dengan curah hujan harian rata-rata 8 mm/hari dan suhu harian rata-rata mencapai 25,5°C. Tipe habitat yang ada meliputi lahan basah, lahan pertanian, perumahan, tegakan campuran, tegakan sejenis, dan taman. Identifikasi teritori wiwik kelabu dilakukan dengan metode pemetaan teritori. Identifikasi sebaran burung inang dilakukan dengan sensus dan observasi langsung. Pemilihan jenis burung inang untuk uji playback didasarkan pada kemudahan individu yang ditemui di setiap teritori wiwik kelabu. Sampel suara wiwik kelabu diambil dari hasil rekaman passive acoustic monitoring (PAM) pada bulan September 2022 hingga Mei 2023. Kriteria pola suara yang diambil yaitu jelas dan bebas dari kebisingan. Pola suara vokalisasi yang diuji yaitu “tii-tu-tit”, “wii-wiik”, “tweit…”, dan “wik-teuu-we”. Pengujian suara playback wiwik kelabu dan burung inang dilakukan di lokasi teritori wiwik kelabu pukul 06.00-10.00 pada bulan Juli-Agustus 2024. Jumlah ulangan uji playback sebanyak 100 ulangan yang terbagi menjadi 40 ulangan untuk respons wiwik kelabu dan 60 ulangan untuk respons burung inang. Pengamatan perilaku wiwik kelabu dan burung inang dilakukan dengan metode focal animal sampling. Durasi pengamatan respons burung target dilakukan selama 4 menit. Metode analisis yang digunakan pada penelitian ini meliputi analisis peta teritori, analisis spektrogram, analisis MANOVA, dan uji chi-square. Analisis peta teritori untuk menentukan batas lokasi penelitian. Analisis spektogram untuk mendapatkan nilai spektogram berupa durasi (s), amplitudo (u), dan frekuensi (Hz) pada setiap respons suara playback. Analisis MANOVA untuk mengetahui hubungan respons suara wiwik kelabu terhadap tipe pola suara playback dari wiwik kelabu yang diputar. Uji chi-square dilakukan untuk memeriksa apakah ada hubungan antara stimulus playback yang diberikan terhadap respons perilaku burung inang. Data pendukung lain dianalisis secara deskriptif dalam bentuk gambar, tabel, maupun diagram. Hasil penelitian ini menunjukkan bahwa ada 13 teritori wiwik kelabu di Kampus IPB Dramaga. Batas teritori dapat terdeteksi dengan jelas pada bulan Maret-Juli atau ketika peralihan musim hujan ke musim kemarau. Jenis burung inang wiwik kelabu yang dapat dijumpai selama pengamatan yaitu cinenen jawa (Orthotomus sepium) dan cipoh kacat (Aegithina tiphia). Aktivitas vokalisasi wiwik kelabu dapat berlangsung dalam periode pendek (1-3 menit) dan periode panjang (3-10 menit). Kriteria dahan atau ranting yang sering dipilih oleh wiwik kelabu untuk bertengger dan berkicau yaitu dahan atau ranting yang relatif terbuka dari dedaunan, berada di ujung atas kanopi pohon, dan pada ketinggian sekitar 10-20 meter. Pemutaran playback dengan pola “tii-tu-tit” menunjukkan respon komunikasi dan wiwik kelabu cenderung mendekati sumber suara. Pemutaran playback dengan pola “wii-wiik” menunjukkan respon penandaan teritori dan persaingan dengan individu lain. Pemutaran playback dengan pola suara “tweit…” tidak menunjukkan perubahan respon perilaku dari wiwik kelabu. Pemutaran dengan pola “wik -teuu-we” menunjukkan perilaku pengusiran individu lain dari wilayahnya. Hasil MANOVA menunjukkan efek multivariat yang signifikan dari jenis playback terhadap respons akustik wiwik kelabu, seperti yang ditunjukkan oleh keempat statistik uji (misalnya, Wilks' Lambda: p = 0,017; Pillai's Trace: p = 0,040). Hal ini mengindikasikan bahwa wiwik kelabu merespons secara berbeda terhadap setiap pola suara uji. Pengujian suara playback wiwik kelabu terhadap burung inang seperti cinenen jawa dan cipoh kacat menunjukkan perilaku yang beragam. Respons perilaku burung inang yang dapat diamati dapat dikelompokkan menjadi empat perilaku yaitu sembunyi (hiding), mencari makan (foraging), membalas kicauan (song vocalization), dan panggilan peringatan (alarm call). Hasil uji chi-square menunjukkan respons perilaku burung inang yang berbeda-beda karena dipengaruhi oleh jenis pola suara playback wiwik kelabu (?² = 14,79, df = 9, p = 0,0969). Perilaku yang paling sering dilakukan ketika diputar playback wiwik kelabu adalah sembunyi. Penelitian mengenai wiwik kelabu memiliki peran penting dalam mendukung upaya konservasi ekologi lanskap. Sebagai burung parasit, wiwik kelabu berkontribusi dalam mengatur populasi burung inang. Ketergantungannya pada sarang burung inang untuk berkembang biak menunjukkan bahwa kelestarian spesies ini sangat bergantung pada kelangsungan hidup burung inang di habitat yang sama. Oleh karena itu, penelitian ini perlu dikembangkan lebih lanjut dengan menitikberatkan pada kajian interaksi wiwik kelabu di sekitar sarang burung inang.

Birds use vocalizations to communicate, which can be divided into calls and songs. Cuckoos in the family Cuculidae exhibit a unique breeding behavior known as brood parasitism. One species of cuckoo bird is the plaintive cuckoo (Cacomantis merulinus), which parasitizes the nests of many bird species and is poorly studied because it is difficult to observe. The acoustic playback method is suitable for studying the plaintive cuckoo by attracting individuals to a specific location and observing their behavioral responses. This study aims to 1) identify the territory of the plaintive cuckoo, 2) identify the distribution of host birds, 3) describe the behavior and predict the function of the plaintive cuckoo's vocalizations, and 4) test the response of host birds to the plaintive cuckoo's playback sounds. The study was conducted at the IPB Dramaga Campus (267 ha) from March to August 2024. The study area is located in a tropical region with an average daily rainfall of 8 mm and an average daily temperature of 25.5°C. The habitat types include wetlands, agricultural land, residential areas, mixed stands, monoculture stands, and parks. The territory mapping method was used to identify the territory of the plaintive cuckoo. The distribution of host birds was determined by censuses and direct observations. The selection of host bird species for playback testing was based on the likelihood of encountering individuals within each plaintive cuckoo territory. The plaintive cuckoo vocalization samples were taken from passive acoustic monitoring (PAM) recordings from September 2022 to May 2023. The selected sound patterns met the criteria of being clear and free from noise. The tested vocalization patterns included "tii-tu-tit," "wii-wiik," "tweit...," and "wik-teuu-we." The playback testing of the plaintive cuckoo and host birds was conducted at the plaintive cuckoo's territorial locations from 06:00 to 10:00 between July and August 2024. A total of 100 playback trials were conducted, consisting of 40 trials to observe the response of the plaintive cuckoo and 60 trials to observe the response of the host birds. Observations of the plaintive cuckoo and the host bird’s behavior were made using the focal animal sampling method. The duration of the behavioral response observations for the target birds was 4 minutes. The methods of analysis used in this study include territorial mapping analysis, spectrogram analysis, MANOVA analysis, and chi-square test. Territorial map analysis to determine the boundaries of the research location. Spectrogram analysis to obtain spectrogram values in terms of duration (s), amplitude (u), and frequency (Hz) in each playback sound response. MANOVA analysis to determine the relationship between the plaintive cuckoo sound response and the type of pattern of the plaintive cuckoo pattern being played. Chi-square test was performed to determine if there was a relationship between the playback stimulus given to the host bird's behavioral response. Other supporting data were analyzed descriptively in the form of pictures, tables, or graphs. The results of this study indicate that there are 13 territories of the plaintive cuckoo on the IPB Dramaga campus. Territorial boundaries were clearly visible from March to July, especially during the transition from the rainy season to the dry season. The host bird species of the plaintive cuckoo observed during the study included the olive-backed tailorbird (Orthotomus sepium) and the common iora (Aegithina tiphia). The vocalization activity of the plaintive cuckoo can occur in short periods (1–3 minutes) and long periods (3–10 minutes). The preferred perching and singing branches are those that are relatively open to foliage, located at the upper edges of the tree canopy, and at a height of approximately 10–20 meters. Playback of the "tii-tu-tit" pattern indicates a communicative response, with the plaintive cuckoo tending to approach the sound source. Playback of the "wii-wiik" pattern indicates territorial marking and competition with other individuals. Playback of the "tweit..." sound does not elicit any response changes. Playback of the "wik-teuu-we" pattern shows a behavior of repelling other individuals from its territory. MANOVA results demonstrated significant multivariate effects of playback type on the acoustic responses of the plaintive cuckoo, as shown by all four test statistics (e.g., Wilks’ Lambda: p = 0.017; Pillai’s Trace: p = 0.040). This indicates that the plaintive cuckoo responds differently to each test sound pattern. The playback testing of the plaintive cuckoo on host birds such as the olive-backed tailorbird and the common iora resulted in a variety of behavioral responses. The observed host bird responses could be categorized into four behaviors: hiding, foraging, singing, and alarm calls. Chi-squared test results indicated that the variation in host bird responses was influenced by the type of playback sound pattern of the plaintive cuckoo (?² = 14,79, df = 9, p = 0,0969). The most frequently observed behavior in response to the plaintive cuckoo playback was hiding. Research on the plaintive cuckoo plays an important role in efforts to conserve ecological landscapes. As a brood parasite, the plaintive cuckoo can help regulate the populations of its host bird species. Its reliance on host bird nests for reproduction means that the species’ sustainability is closely linked to the stability of host bird populations. Further studies are needed to explore the interactions between the plaintive cuckoo and its host species, particularly around nesting sites.