Diario de notoriousbiologist

SYNOPSIS

The remaining Forest in the areas of Alikoson-Macabol Mountains has been known to accommodate a pair of Philippine Eagle since 1986. A total of 4 known nesting trees has been monitored within the area. Since its discovery, the pair has been regularly producing offspring every breeding season, up until last 2014 -2015 breeding season. We suspect that the eagle pair has been nesting on a new nest tree since 2015. The objective of this year’s monitoring is to find that new nesting tree.
In this 1-day activity, a team was sent to conduct preliminary survey and reconnaissance of possible observation posts for future Philippine Eagle monitoring.

METHODOLOGY

Philippine Eagle Post Monitoring Survey

Last June 8, the team visited an observation post (OP) just adjacent from Sitio Falcata (see figure 1, Map). This area was occupied before during 2013-2015 Philippine eagle monitoring. As compared to rigorous hikes on the other day, going to the post observation site was relaxing, where the team only spend 30 minutes in walking. Equip with monitoring equipment the team scans the wide and overlooking area of the OP for any passing raptors seen during the activity. The team also discussed as to which sites should be visited on the next 10-day expedition.
For post monitoring and observations, the team used “look-and-see” method (Bibby, et al., 1998) accompanied with the following devices; three pieces of binoculars (2 Nikon Monarch 8x42, and 1 Swarovski 8x30 magnifications), one fieldscope (Swarovski optik) and a zoom-lensed camera (Canon EOS 800D head and Tamron 150-600mm lens) in recording observations for flying raptors and other birds. For other raptors and birds, the team listed each species they encountered during the fieldwork. All documented birds were identified using “A guide to the birds of the Philippines” book (Kennedy, et al., 2000) and were updated down to their species level using the “Checklist of Birds of the Philippines 2019” (Jensen, et al., 2019).

RESULTS

From our observation post, the team overlooked the forested areas of Masawang (previous nesting site in Alikoson forest) going to Sitio Kiandong, and Sitio Lais forested areas. During the whole day activity last June 8, the team did not detect any sightings of Philippine Eagle. Though based on our random interviews, the locals from Sitio Taupan and Sitio Tribal has reportedly seen sightings of Philippine Eagle recently.
A total of 8 hours was spent for observations during the activity, last June 8, 2022. Though there were no sightings of Philippine Eagle during the one-day survey, the team manage to detect four forest raptors. Namely the Philippine Serpent Eagle (Spilornis holospilus), Philippine Honey buzzard (Pernis steerei), Brahminy Kite (Haliastur indus), and Pinsker's Hawk-eagle (Nisaetus pinskeri), and 75 % of these detected raptors were endemic.
All and all the team documented 42 bird species belonging to 26 families were recorded namely Phasianidae, Rallidae, Accipitridae, Columbidae. Cuculidae, Apodidae, Trogonidae, Meropidae, Bucerotidae, Megalaimidae, Picidae, Psittaculidae, Artamidae, Campephagidae, Pachycephalidae, Corvidae, Paridae. Pycnonotidae, Cettiidae, Locustellidae, Zosteropidae, Sittidae, Sturnidae, Muscicapidae, Dicaeidae, and Nectariniidae (Annex).
Out of 42 species, 38% (16 species) were resident, and 61% (26 species) were endemic species (Annex). Part from the species listed during the activity includes the IUCN “Endangered” species Pinsker's Hawk-Eagle (Nisaetus pinskeri), the “Vulnerable” species Mindanao Rufous Hornbill (Buceros hydrocorax mindanensis), and the “Near Threatened” species namely the Writhed Hornbill (Rhabdotorrhinus leucocephalus) and the Lina's Sunbird (Aethopyga linaraborae) (IUCN, 2019). In such short opportunistic avifaunal survey, the team infers that the site holds plenty species of birds that where unrecorded, and highly recommends a further elaborative study. In addition, with rare and threatened species recorded, the site isan important habitat serving as important haven for this avifaunal species.

Table 1. List of Birds during the activity

Family Common Name Uvo Manuvu Name Scientific Name

Phasianidae Red Junglefowl Manok Gallus gallus
Rallidae Plain Bush-hen Tung-giyok Amaurornis olivacea
Accipitridae Brahminy Kite Monou' Haliastur indus
Accipitridae Pinsker's Hawk-Eagle Baog ta lutang' Nisaetus pinskeri
Accipitridae Philippine Serpent Eagle Kulihi Spilornins holospilus
Accipitridae Philippine Honey Buzzard Maninigbas Pernis steerei
Columbidae White-eared brown dove Alimokon Phapitreron leucotis
Cuculidae Philippine Coucal Kokok Centropus viridis
Cuculidae Black-faced coucal Lambugan Centropus melanops
Cuculidae Rusty-breasted Cuckoo Tiduding Cacomantis sepulcralis
Apodidae Ridgetop Swiftlet Sayaw Collocalia isonota
Trogonidae Philippine Trogon Ak-ak Harpactes ardens
Meropidae Blue-tailed Bee-eater Puloy-puloy Merops amercanus
Bucerotidae Rufous Hornbill Kalyawa Buceros hydrocorax mindanensis
Bucerotidae Mindanao Tarictic Hornbill Tugkos Penelopides affinis
Bucerotidae Writhed Hornbill Kayamutan Rhabdotorrhinus leucocephalus
Megalaimidae Coppersmith Barbet Pokpok Psilopogon haemacephalus
Picidae Philippine Pygmy Woodpecker Yungipicus maculatus
Psittaculidae Blue-crowned Racket-tail Kullet Prioniturus discurus
Artamidae White-breasted Woodswallow It-it Artamus leucorynchus
Campephagidae Scarlet Minivet Kuryot Pericrocotus speciosus
Campephagidae Pied Triller Sagksak Lalage nigra
Pachycephalidae Yellow-bellied Whistler Broing Pachycephala philippinensis
Corvidae Large-billed Crow Uwak Corvus macrorhynchos
Paridae Elegant Tit Kalimot-limot Pardaliparus elegans
Pycnonotidae Philippine Bulbul Bayako Hypsipetes philippinus
Pycnonotidae Yellow-vented Bulbul Ullou Pycnonotus goiavier
Cettiidae Mountain Tailorbird Kalinsawi Phyllergates cucullatus
Locustellidae Striated Grassbird Chakokok Megalurus palustris
Zosteropidae Warbling White-eye Katiyo Zosterops japonicus
Sittidae Sulphur-billed Nuthatch Padidit Sitta oenochlamys
Sturnidae Coleto Sal-ing Sarcops calvus
Muscicapidae Little Pied Flycatcher Tamsi Ficedula westermanni
Alcedinidae White-throated Kingfisher Tingkarol Halcyon smyrnensis
Dicaeidae Red-keeled Flowerpecker Tamsi Dicaeum australe
Dicaeidae Orange-bellied Flowerpecker Tamsi Dicaeum trigonostigma
Dicaeidae Buzzing Flowerpecker Tamsi Dicaeum hypoleucum
Dicaeidae Pygmy Flowerpecker Tamsi Dicaeum pygmaeum
Dicaeidae Fire-breasted Flowerpecker Dicaeum ignipectus
Nectariniidae Lina's Sunbird Tamsi Aethopyga linaraborae

Rowell L. Taraya
Philippine Eagle Foundation, Philippine Eagle Center, Malagos, Baguio District, 8000 Davao City

ABSTRACT

(see this article https://www.sunstar.com.ph/article/1881201/davao/local-news/search-for-a-philippine-eagle-family-at-mt-apo-geothermal-reservation )

The Philippine Eagle Foundation (PEF) endeavors to find all eagle nesting sites within the Mt. Apo Key Biodiversity Area (KBA) and help protect each of these nest sites. Philippine eagle nest sites are ancient breeding areas – generations of eagle pairs have occupied the same nest site over and over again. Conserving these core areas of reproduction and keeping the nesting pair and their young safe is pivotal to the success of saving the species from being lost forever. In 2019, the PEF, Energy Development Corporation (EDC), and the Department of Environment and Natural Resources (DENR) launched the “Search for the King of Birds” project at the western slopes of Mt Apo. The search began at the Mt. Apo Geothermal Reservation in Kidapawan City where eagles were seen in the past. Apart from enhancing local awareness and capacity for eagle conservation, project implementers also wanted to find and study an eagle pair and their active nest at the reservation. After spending 192 observation hours deep in the forest finding and documenting Philippine eagles and other raptors, the team managed to detect one eagle pair and their two-year-old young.

INTRODUCTION

THE Philippine Eagle Foundation (PEF) endeavors to find all eagle nesting sites within the Mt. Apo Key Biodiversity Area (KBA) and help protect each of these nest sites. Philippine eagle nest sites are ancient breeding areas – generations of eagle pairs have occupied the same nest site over and over again. Conserving these core areas of reproduction and keeping the nesting pair and their young safe is pivotal to the success of saving the species from being lost forever.

In 2019, the PEF, Energy Development Corporation (EDC), and the Department of Environment and Natural Resources (DENR) launched the “Search for the King of Birds” project at the western slopes of Mt Apo. The search began at the Mt. Apo Geothermal Reservation in Kidapawan City where eagles were seen in the past. Apart from enhancing local awareness and capacity for eagle conservation, project implementers also wanted to find and study an eagle pair and their active nest at the reservation. Two expeditions in 2019, one in July and another in September, found one Philippine eagle. The bird is suspected to be immature, perhaps over 3 years old, and thus is a floater (sexually immature and unpaired eagle). The presence of an immature eagle indicates that its eagle parents could be nearby. The PEF Team -- Senior Biologist Ron Taraya and Field Intern Keanu Sitjar -- together with EDC Forest Aides Climclim Lumayon and Renjie Sinding, embarked on the month-long expedition in November 2020 to check on a possible new nesting territory of the Philippine Eagle.

The group focused their eagle search on the forests where a lone Philippine eagle was detected in2019. The terrain at the survey site was very steep, and the forest vegetation is lush. With binoculars and field telescopes, the team alternately manned four observation posts (OP): three on the ground (OP1-3) and one on an elevated platform (OP4). OP4 offered the closest view of the gorge and its forests. After spending 192 observation hours deep in the forest finding and documenting Philippine eagles and other raptors, the team managed to detect one eagle pair and their two-year-old young.

RESULTS

Confirming a Philippine eagle couple

It was on November 4, 2020 when the team saw their first Philippine Eagle pair. The first eagle was found perched inside the canopy above the waterfalls. The bird then took off and flew in circles above the falls. As it was about to head towards the other hill, another eagle appeared and started “chasing” the other eagle. The team recalled that their hearts raced at the sight of the eagles doing their elegant aerial rituals.

The eagle couple then began what appears to be a courtship routine. The two eagles mutually presented their talons in mid-air called “talon presentation”. They also did several bouts of flying together in spirals or “mutual soaring”. Then they flew to different directions; one disappearing inside the deep gorge, while the other landed on an emergent tree. There, the eagle stayed on its perch cleaning its feathers with its beak called preening. It was also seen scratching, stretching, and moving its head. After performing these general maintenance behaviors, the eagle finally flew off and glided beyond the waterfalls until it disappeared behind the tree line.

In Mindanao, September to January is the nesting season for Philippine eagles, and courtship displays precede each egg-laying. Eagle pairs at several nests sites of Mindanao start their courtship rituals above their nesting area as early as July, but the routine can last even until the pair is already rearing a chick. These observations strongly suggest that the forest the team investigated is a new Philippine eagle nesting territory at the Mt. Apo KBA.

Documenting a juvenile Philippine Eagle

On November 5, 2020, while occupying OP 2, the team was eager to see “prey delivery” and/or “sprig delivery” behaviors that would lead them to a possible nest. To the group’s great delight, two eagles were spotted. The eagles glided steadily on a level cruise, with one trailing the other. They emerged from the same spot where one of the eagles disappeared the day before. One eagle landed on a tree that is visible to the group, while the other rested on a concealed spot. While observing the pair, the team then heard loud, crying calls from another eagle. The calls were typical of “food-begs” from a very hungry young eagle. Food-begging calls are mostly exhibited by juveniles whenever an attending parent is nearby. The hungrier the eaglet, the louder its calls get. The team occupied the post early the following day in anticipation of another eagle encounter. It was early in the morning when loud eagle calls were heard once again. The “food-begs” echoed across the forests and it took the team a while to find the eagle. Finally, the eagle emerged out of a tree directly above the waterfalls. The bird was over a kilometer from the research team’s post, and at that distance, it was very difficult to see the bird’s physical features in detail. One can tell whether a bird is a juvenile or adult based on the shape of its feathers, the color of its legs, and its general appearance. The birdcalls resemble infantile vocals, but the team needed to have a closer look to be sure. An adult delivering food and feeding the eagle is another proof that the bird is a juvenile. While observing the eagle, an adult eagle appeared above the ravine and flew towards the direction of the calling bird. The adult eagle was seen to be carrying a freshly killed prey. The “food begs” intensified as the other eagle flew above the ravine. Minutes later another eagle appeared behind the forests. The eagles were not seen for several days after this encounter. To know for certain if the tree is a nesting tree, the team decided to find a closer observation post at the forest edge on November 12. Upon closer inspection of the tree, it showed that it does not qualify as a suitable nesting tree. It did not have the typical nest bowl structure, the associated thick ferns, and other epiphytes that one will find in an old nest. It appears that the tree is more of a “feeding tree” than a nesting tree. On November 13, the established OP4 – an elevated platform that gave them a good view of the whole forest. The following day, they occupied our new platform and waited. It was in the afternoon when two Philippine eagles were again spotted circling just above the ridge. But the mutual soaring did not last a minute. Only one Philippine eagle landed on a spot that is visible to the team. The other eagle, which they suspect is the juvenile, hid behind the foliage. They heard it calling but never saw it for the rest of the day. The team had another encounter with the juvenile Philippine Eagle on November 19 after it soared just above OP 4. Now closer to the bird, about 200 to 300 meters, the relatively sword-tipped flight and tail feathers of the juvenile eagle were visible. The bird also had all the other features typical of a two-year-old juvenile such as awkward hunting moves, lower flight confidence, and limited flight duration. The juvenile eagle was also observed to hunt when it took on a group of long-tailed macaques(Macaca fascicularis) foraging on an escarpment just in front of the waterfalls. Researchers saw the bird leaping from the tree and darting towards the macaques. The macaques panicked and ran frantically in different directions to avoid the eagle. While it did attempt to corner a macaque, the juvenile eagle’s attempt to hunt was unsuccessful as the macaque it had its eye on was able to escape. The macaques were also observed to have rallied together to scare off the eagle.
Aside from detecting the critically endangered Philippine eagle, seven other raptors seen during the expedition. These raptors are the Philippine Eagle (Spilornis holospilus), PhilippineHoney buzzard (Pernis steerei), Brahminy Kite (Haliastur indus), Philippine Falconet (Microhieraxerythrogenys), Chinese sparrowhawk (Accipiter soloensis), the crested honey buzzard (Pernisptilorhynchus), and the Peregrine falcon (Falco peregrinus). (PEF)

Ron Taraya and Jayson Ibanez. Ron and Jayson are Biologist and Director for Research and Conservation, respectively, at the Philippine Eagle Foundation