Dinamika Migrasi Raptor Di Lanskap Semarang

KARYADI BASKORO, Prof. Dr. JUSUP SUBAGJA, M.Sc; Dr. SATYAWAN PUDYATMOKO, M.Sc; Prof. Dr. TJUT S. DJOHAN M.Sc

2017 | Disertasi | S3 Biologi

Penelitian tentang migrasi raptor di Indonesia sudah dilakukan di beberapa daerah. Namun untuk Pulau Jawa masih minim data ekologinya dan belum ada data untuk periode migrasi balik. Lanskap Semarang sebelumnya diduga tidak merupakan rute migrasi raptor, namun ternyata kemudian tercatat keberadaanya. Penelitian ini bertujuan untuk mengkaji dinamika migrasi raptor di lanskap Semarang, meliputi: 1) dinamika selama musim migrasi balik tahun 2006-2013 dan satu musim penuh 2013-2014, mencakup: komposisi jenis dan cacah individu; respon terhadap kondisi habitat. 2) dinamika temporal perilaku pergerakan, meliputi: gaya, tinggi, waktu, kelompok, dan arah terbang; respon terhadap kondisi habitat. 3) mempelajari pola rute raptor migran di lanskap Semarang terkait dengan kondisi tata guna lahan dan geomorfologi. Pra survei dilakukan untuk mencari rute migrasi potensial. Lokasi paling potensial dipilih berdasar kriteria tingginya frekuensi perjumpaan dan cacah individu. Pada lokasi terpilih dilakukan pendataan setiap hari selama puncak musim migrasi balik, pada bulan Maret. Dilakukan pula pengamatan satu tahun penuh, dari bulan Agustus 2013 sampai Juli 2014. Pada semua waktu pengamatan, dilakukan pendataan jenis dan individu, perilaku pergerakan dan kondisi habitat. Cacah individu antar jenis dibandingkan dengan uji Kruskal Wallis. Pola dinamika populasi dianalisis dengan metode regresi polinomial. Perilaku pergerakan antar jenis dibandingkan dengan uji Chi-square.Analisis respon antara komunitas raptor dengan kondisi habitat dengan menggunakan Canonical Component Analysis (CCA). Pola rute raptor migran dalam lanskap dianalisis dengan metode pemetaan. Data kondisi geomorfologi dan tata guna lahan di ekstrak pada sepanjang rute migrasi di lanskap Semarang. Hasil menunjukkan bahwa lanskap Semarang merupakan salah satu rute migrasi utama raptor migran untuk wilayah Jawa bagian tengah, khususnya untuk musim migrasi balik. Hal ini didukung oleh data jumlah dan frekuensi lintasan yang selalu kontinu. Populasi raptor migran yang melintas di lanskap Semarang memiliki fluktuasi individu harian maupun tahun. Pola asosiasi fluktuasi individu dengan faktor lingkungan memperlihatkan variasi antar tahun, namun memiliki kecenderungan utama berkaitan dengan kecepatan angin, curah hujan, dan suhu. Pergerakan raptor migran memiliki variasi pola gaya, tinggi, kelompok, dan arah terbang. Gaya dan tinggi terbang berkaitan dengan kondisi termal di sepanjang lanskap. Raptor cenderung memilih strategi terbang secara kelompok tunggal. Arah terbang memiliki kecondongan dipengaruhi oleh arah angin di sepanjang lanskap. Pola rute utama migrasi raptor di lanskap Semarang memiliki ciri kondisi geomorfologi dan tata guna lahan yang khas. Rute lintasan memiliki variasi ketinggian dan tingkat kelerengan sedang. Karakter tata guna lahan didominansi oleh tutupan vegetasi.

Research on raptor migration in Indonesia is already done in some areas. But for Java is still inadequate in ecological data and lack for the period of spring migration. Semarang landscape previously allegedly not as raptor migration route, but then recorded its existence. This study aims to assess the dynamics of raptor migration in the Semarang landscape, include: 1) dynamics during migration season through the year 2006 to 2013 and a full season from 2013 to 2014, include: species composition and individual count; response to habitat conditions. 2) temporal dynamics of the movement behavior, include: style, height, time, groups, and their flight direction; response to habitat conditions. 3) study the pattern of raptor migration route along Semarang landscape, associated with the condition of land use and geomorphology. Pre-surveys were conducted to look for potential migration route. The most potential location selected based on the criteria of the high frequency and individual encounter. At selected location, data collected every day during the peak migration season in March. Observations also conducted for a full seasson, from August 2013 until July 2014. In all the time of observation, data of species, individual, behavioral movements and habitat conditions was recorded. Individual count among species were analyzed with Kruskal Wallis test. The pattern of population dynamics were analyzed by polynomial regression method. Behavioral movement between species were analyzed by Chi-square test. Analysis of responses between raptor communities to habitat conditions by using Canonical Component Analysis (CCA). Raptor migration route pattern in the landscape is analyzed by the mapping method. On the path along the landscape, geomorphological conditions and land use data was extracted. The results showed that the Semarang landscape is one of main raptor migration route for Central Java. This is supported by continuity data of number and frequency. Populations of raptor migrants passing through the Semarang landscape have individual fluctuations both daily and years. Association pattern of individual fluctuations with environmental factors showed variations between years, but has major trends related to wind speed, precipitation, and temperature. Raptor migration movement behavior has variation of style, height, group, and flight direction. Style and flight height related to thermal conditions across the landscape. Raptor tends to choose flight strategies in a single group. Flight direction tends to influenced by the wind direction along the landscape. Main pattern of raptor migration route in the Semarang landscape characterized by specific geomorphological conditions and land-use characteristic. The route has variation in altitude and a moderate degree of slope. Land use characters dominated by vegetation cover.

Kata Kunci : burung pemangsa, migrasi balik, dinamika populasi, rute migrasi