Dr. Jayson C. Ibanez, Rowell Ron Taraya, Julia Lynne Allong
Philippine Eagle “Uswag”, a three-year old male eagle, was released at Marabong Watershed of the Anonang Lobi Range KBA in Burauen, Leyte last June 28, 2024. Together with female eagle “Carlito”, they were the first batch of eagles to be released in Leyte under the Species Reintroduction Project for the IUCN “critically endangered” Philippine Eagle by the DENR and the Philippine Eagle Foundation (PEF). The eagle was instrumented with a 70-gram, solar-powered GPS-GSM transmitter to help with tracking and monitoring of the bird post-release. The device was strapped on the back of the bird (backpack style) using a teflon harness.
Near midnight of July 30, 2024, Jayson Ibanez (first author) received the latest set of GPS readings from Uswag’s unit through email, and mapping of the GPS fixes on Google Earth showed that all of the readings for that day were already at sea. There were a total of 26 GPS coordinates transmitted, starting at 12:04 hr (noontime) until 19:59 hr. The last GPS reading that was received before July 30 was the July 9 reading, and the batch of GPS coordinates for that day was at the western slopes of the Mt. Pangasugan Range in Baybay City (see Figure 1). The ground distance between the last GPS coordinates on July 9 and the first GPS fix on July 30 is 5.98 km.
Figure 1. Philippine Eagle 'Uswag" inside his acclimatization cage in Brgy Kagbana, Burauen before his release.
On the afternoon of July 31, Dr. Jayson Ibanez flew to Tacloban City to meet with the third author (Julia Allong) and arranged a “search and recovery” operation for eagle “Uswag”. On the same day, partners from the BMB, DENR, EDC, and RCCTC were informed about Uswag’s situation. Letters were also sent to the Department of National Defense (DND) and Department of Transportation (DOTr) requesting possible air and sea assets to aid the search. Later that night, a meeting with DENR 8 staff Marissa Solite and Ingelina Lantajo, PENRO Leyte Winston Solite and Fr. Calvin Bugho of RCCTC was held to discuss and finalize the search plan.
The succeeding narratives below highlight the daily results of the search and retrieval operation, the discovery of Uswag’s carcass, the x-ray and post-mortem examination of the bird, and some insights and conservation implications of the incident.
Figure 2. Batch of GPS fixes from Uswag’s GPS transmitter dated July 30, 2024. All of the readings were already at sea off Baybay City coast.
August 1, 2024 (Baybay coast of Brgy. Gabas)
On August 1, we started our search off the sea of Baybay shoreline after a proper courtesy visit and coordination with LGU Baybay City, CENRO Baybay and the Baybay’s resident Coast Guard. On board the Baybay LGU’s rescue boat, we began our search from the coasts of Brgy. Gabas at 12:09 hr and headed straight to the where the last GPS fix on July 30 is located. Binoculars were used to aid the search, then we expanded our search to adjacent areas based on the Coast Guard assessments of wave directions and where the bird might have drifted to; however, rains started to pour, and we were forced to abort the search at 13:36 hr. We logged a total of 14.08 man-hours (10 personnel x 1.28 hours of search) and covered about 700 hectares of seas during this particular search effort.
We spent the rest of the afternoon meeting with VSU College of Forestry and College of Veterinary Medicine officials and arranged a necropsy plan in the event that Uswag’s body is retrieved. We also spent time at CENRO Baybay mapping and analyzing our search efforts for the day, and further planning the following day’s modus operandi.
August 2, 2024 (Baybay Pier to Cuatros Islas)
We hopped on the rescue boat and took off from the Philippine Ports Authority pier at 09:35 hrs and began searching the seas between the last GPS fix of July 30, and the Cuatro Islas - which is located southwest of the last GPS fix. We mapped out and measured the distances between each of the GPS fix of July 30, and we calculated a drift rate for Uswag at 625 m/hour. With this rate and the coast guard’s knowledge of wave patterns, we inferred the possible places where the bird/unit has drifted since the last GPS fix.
After reaching the islands of Digyo and Apid, we met with the leaders of two villages and asked their help with sharing any report of fishermen who might have encountered a dead Philippine eagle at sea. For this particular search, we logged a total effort of 32.8 man-hours and covered 6,000 ha of seas. Unfortunately, we failed to find Uswag.
While on our way back to the port, I (first author) received a new batch of GPS fixes via email, and the latest GPS fix was already along the coast between Poro and Ponson Islands (Camotes Islands) in Pilar, Cebu. Back to the port, we re-grouped and planned for the following day’s search operations at the Ponson Island. Upon our request, we were endorsed by Coast Guard (CG) Headquarters to the North Pilar CS sub-station whom we then contacted to arrange the details of the search. LGU Baybay and CG Baybay agreed to ferry us to Pilar and turn us over to their counterparts on the island.
Figure 3. Aug 2 batch of GPS fixes from Uswag's transmitter showing its latest location between Poro and Ponas Islands Camotes Islands).
August 3, 2024 (Ponson Island, Pilar, Cebu)
Joined by PEF Senior Biologist Ron Taraya, PEF Technician Rene Bacquiano, and Inquirer Correspondent Joselle Badilla, we left Baybay Port at 8:00 AM and arrived at the Northern Pilar pier in Ponson Island at around 9:30 AM. After a short meet-and-greet with our new host, we did a quick meeting and briefing with the CG team there. A motorized fishing boat for the search was arranged and re-fueled for the search.
Figure 4. Planning our search route with the Coast Guards stationed at the Northern Pilar Sub-Station, Pilar, Cebu
At 10:20 hrs, we began our search on board the motorized fishing boat provided by LGU Pilar. While scouring the northern eastern seas of Pilar, I received a new batch of GPS fixes at 11:24 hr and the latest reading was located about half km away from the shores of Brgy. Cawit in Southern Pilar. We headed straight to Cawit and began another bout of search there. Three additional motorized boats joined in the search with the boats occupied by PEF and CG personnel and volunteer fishermen from Cawit. After logging a total effort of 42 man-hours and covering 1,149.6 ha of sea between Northern Pilar and Brgy. Cawit, we finally found Uswag’s lifeless body floating together with a debris of sea grass and algae.
Figure 5. PEF Operations Director Jayson Ibanez and PEF Senior Biologist Ron Taraya loads the latest GPS fix unto the GPS tracking device during the search off Ponson Island.
Finding and retrieving Uswag’s carcass
When we were just about to lose hope, at 3:30 PM, CG ASN Patalinghug spotted "Uswag," floating in an area known as "Samo," where two different sea currents meet. Shortly thereafter, Fisherman volunteer Mark Bryan Marquezo Colminas retrieved Uswag from the water. Uswag was found floating along with sea debris with its GPS transmitter facing upward and its miniature solar panels exposed to the sun (see Figure 6). The body was already beginning to decompose.
Figure 6. Coast Guard Pilar personnel leading the search from the second boat at Brgy Cawit, Ponas Island
After retrieving Uswag’s carcass, we secured it inside a styrofoam box cooler, with ice filling the cooler to help in preserving the carcass. The carcass was placed inside a garbage bag. The team with the carcass then took the LGU Pilar Van to the Northern Pilar pier and prepared to leave for Baybay City. We hopped on our chartered boat and left the pier at around 18:00 hrs. Two Pilar CG escorted the team back to Baybay City and we safely reached the pier at 20:00 hrs. While in transit, an X-ray appointment and a Necropsy examination were arranged for August 4 with the help of Dr. Dennis Peque and Dr. Marjorie Cortes of VSU.
Figure 7. Last batch of GPS fixes (Aug 3) from Uswag's transmitter that guided the successful search and retrieval of the eagle's carcass and satellite GPS/GSM transmitter at Brgy Cawit, Pilar, Cebu.
Figure 8. A. Carcass of Philippine Eagle "Uswag" floating together with sea debris. B. Minutes after retrieval of
Philippine Eagle Uswag’s carcass.
Figure 9. PCG Pillar and locals assist in transporting the carcass of Philippine Eagle Uswag back to the mainland, Baybay City.
X-ray and Necropsy results
On August 4 at 09:00 hr, the x-ray examination was made at the Baybay Petlover’s Clinic. Based on Uswag’s X-ray plate, all the bones of the body were intact, and had neither signs of fracture nor trauma. No evidence of bullets or air gun pellets were also found in the x-ray. The veterinarians’ over-all impression is that there was no anomaly evident in the bird’s carcass. Radiographic readings and analyses were undertaken by Dr. Cortes of VSU together with Dr. Dara Bibera, the clinic’s resident veterinarian, with some vet aides assisting her.
From the vet clinic, we proceeded to the VSU College of Veterinary facility for the necropsy. There, post-mortem examination showed evidence of autolysis (bodily enzymes self-digesting cells and tissues) with some of the internal organs, such as liver, heart, and kidneys already disintegrated. The crop and proventiculus were also empty. Over-all, there was no visible evidence of shooting, trauma nor bodily injury and other anomalies. The cause of death is suspected to be drowning, and the estimate time of death of the bird based on the conversation with Dr Cortes is 4-5 days before it was retrieved. The necropsy team was led by Dr. Lotis Balala, Dr. Cortes, and their team of faculty veterinarian. A full necropsy report will be provided by the VSU team within the next few days of this report.
Figure 10. Veterinarians from Baybay Pet Lovers Veterinary Clinic conduct x-ray examination of Philippine Eagle Uswag's carcass.
Figure 11. VSU Veterinarians conducts a necropsy on Philippine Eagle Uswag.
Figure 12. Vets examined internal organs and gastrointestinal tract contents of PE Uswag.
Figure 13. Philippine Eagle Uswag preserved in 40% formalin, placed inside a plastic storage box.
Discussion and Insights
It is very unfortunate that we lost Philippine Eagle ‘Uswag” to accidental drowning. He was healthy and fit, and there were evidences based on field observations that he had already hunted successfully in the wild during the first few days after his release. Sadly, perhaps because of the rains and winds brought about by the Southwest monsoon, eagle “Uswag” lost his flight bearings and got sucked in towards the sea.
This is not the first time that a Philippine eagle had crashed accidentally at sea. Based on PEF records, we have eight cases of immature eagles found by fishermen floating on water (see cases of eagle crashing at sea). Remarkably, all except one of these cases were alive when rescued by their saviors (see Table 1). The eighth case happened in September 2022 at the coast of Maasim town in Sarangani Province. Named “Maasim III”, the bird washed ashore and was already lifeless when it was discovered by fisherfolks; but curiously, two more eagles crashed at the same sea prior to Maasim III - one was in 1993 and the bird was named “Princess Maasim” (now LDI). This bird is currently at the Philippine Eagle Center in Malagos. The second eagle is “Maasim Pride” who was scooped out of the same waters in 2019, but the bird died of a viral disease two months after it was rescued.
Table 1. Records of wild Philippine eagles crashing at sea (7 birds) and a lake (one bird) on Mindanao Island.
There are two more cases of sea crashes that happened within the same general seascape. One eagle named “Dawan” was rescued from Pujada Bay in Dawan, Mati City in 1984. In the same bay but closer to the open sea, Philippine eagle named “Kalayaan” was rescued in Cabuaya, Mati City.
Uswag’s is the 9th case of wild eagles accidentally crashing at sea (one crashed at Lake Lanao). However, he was the first reintroduced wild eagle and the first with a GPS tracking device to crash at sea. The rest of the eagles were untagged, but seven out of 8 birds were miraculously alive and saved by fishermen.
Interestingly, review of the general topography of the mountain range along Baybay City and the western slopes of the Mt Pangasugan Range show similarity with those areas in Mindanao where sea crashed also happened. The nature of thermals (highest at land surfaces and lowest or nil at sea surfaces) and how a predominantly gliding and soaring species like the Philippine eagle depend on them during dispersal) was cited as a plausible explanations to these cases (see cases of eagle crashing at sea). We suspect that the same ultimate cause can explain Uswag’s accidental drowning.
We will further investigate and explore systematic GIS mapping and modelling of topography, wind-patterns, and other climate parameters at these crash sites to determine patterns and assess risks. Doing so can allow us to predict which areas within Leyte and other future release sites, as well as in suitable Philippine eagle habitats across the country have the highest risk of crashes. This, in turn, have very important management and conservation implications particularly in this era where global climate change can exacerbate mortality rates among wild Philippine eagles, which can further drive them to extinction.
Acknowledgements
We extend our heartfelt gratitude to DENR 8 CDD Chief Marissa Solite, PAMBCS Chief Ingelina Lantajo, PERNO Leyte Winston Solite, and CENRO Baybay Elmer Labaclado for their logistical assistance. We are also grateful to LGU Baybay City, particularly Mayor Jose L. Cari, for their gracious welcome and prompt response. We deeply appreciate the invaluable contributions of the City ENRO team, including Engr. Gretel A. Cabrito, For. John Jochiel M. Artajo, Ma. Cris A. Calumba, and Arnel Baring. Our sincere thanks go to the Coast Guard Baybay team—CG PO1 Chris Ian L. Bulawan, CG PO3 Ryan James Y. Villamor, and CG SN1 Calvin G. Tabudlong—for their dedication and hard work. Additionally, we are grateful for the crucial support of Andy Nuñez from DENR-CENRO Baybay, Bithyl V. Valenzona from CFRMO, and Ritchard from CDRMO. We also thank our local contacts at Brgy. Gabas, Baybay City, Sitio Digyo, and Brgy. Apid of Inopacan.
At Pilar, Cebu, we deeply appreciate the support of the Coast Guard Camotes Islands and Pilar team and to Mayor Manuel Santiago for their prompt response and assistance. We are truly grateful for the dedication of CG PO2 Amando C. Iturriaga Jr., CG PO3 Josep C. Neis, CG SN1 John Rick Icaro, CG SN2 Kenneth Tan, CG SN2 Harvey Favila, and CG ASN Patrick Patalinghug, who spotted Uswag. Special thanks to Bayron Berezo and Mark Bryan Marquezo Colminas for their vital roles in retrieving Uswag, as well as Rommel Pilota for his generous contribution. Lastly, we thank the veterinary team of Visayas State University and Baybay Pet Lovers Clinic: Vet Tech Mark Palma, Vet Dara Gayle C. Bibera, DVM, and Vet Nurse Arah Cristyl Aguilar. Senior Vet Clinicians Alexie John Lood, Mark Clemen Palma, and Mark Lou Abela conducted the necropsy and X-ray, with support from Dr. Lotis M. Balala and Dr. Marjorie A. Cortes. Your expertise and dedication were invaluable.
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