Science is not stagnant, but forever updating itself and relearning things. So too with our knowledge of the birds on the Philippines. Besides updated information because of actual changes in the status of bird populations, we also learn new things based on new evidence and new research methods. The Wild Bird Club of the Philippines therefore updates their Checklist of Philippine Birds each year, to reflect changes in taxonomy as well as updated records. A lot of information about the status of the birds of the Philippines is packed into that list; How many birds are there in the Philippines? How many of them are threatened? How many are migrants and how many are endemic?
Number of birds in the Philippines
Very briefly; 709 as of last check. However, not all of these are always in the country, and some have not been sighted for over a century, or are believed to be locally extinct. So some more explanation is warranted.
The science of taxonomy has made great leaps in recent decades. With the advent of DNA studies, new avenues of research are available to determine what a species is, and especially which population(s) contain(s) enough difference from other populations to be called a separate species. This is not the first time this has happened, bird taxonomy has gone through periods of ‘splitting’ and ‘lumping’ before, where a general trend is seen where more species are lumped together, or split from each other. Currently, certainly in the Philippines, there is a lot of splitting going on. More and more species are studied in detail and populations, usually on different islands, are found to contain sufficient variation from other islands population that a subspecies is upgraded to a new species. There are several authorities worldwide who are involved with this. The WBCP follows the line of the International Ornithological Congress (IOC). Each year, the species list for the Philippines is checked for taxonomic revisions, and these changes are reflected in the updated list. This occasionally results in a Philippine taxon becoming an endemic species.
Rising species count over the years
The actual number of bird species endemic to the country is not often changing; it is very rare to discover a completely new species. The last one for the Philippines was the Calayan Rail Gallirallus calayanensis, which was discovered by science (though local people were familiar with it of course) in 2004. As you can see in Table 1, a lot of species and also quite a lot of endemics have been added over the past 20 years. In recent years, although the total number of species has gone up significantly (26 species in the last 5 years), the number of endemics has increased by only 2. These two are the results of a subspecies being upgraded to full species. The vast majority of new species added to the list are due to an increased number of migratory birds that are found to visit the country. Most of these are rare visitors, perhaps accidentally blown off course during inclement weather conditions or other reasons. We therefore call these species vagrants or accidentals.
How many birds are residents, endemic or migrants?
Some birds migrate, and others don’t. Unfortunately, it’s not as straightforward as it seems. Some bird species migrate locally (within the country) and some species have both migratory individuals as well as resident populations. The migratory season also differs from species to species, and is quite stretched out, so it is generally always possible to find migratory birds in the Philippines. Generalizing, though, we can say that the peak in migratory season is October (southbound) and March (northbound). Out of the 709 species recorded in the Philippines, 270 are known to migrate. However, 139 of these are so called ‘accidental’ visitors, with fewer than 20 records (not individuals). That leaves 131 species that migrate, of which 20-25 species have both resident as well as migratory populations.
A total of 450 resident species have been recorded in the Philippines, of which around 20-22 are have migrating individuals. Of these 450 residents, 241 are endemic, and 12 more are almost endemic (near endemic), having populations on small islands that politically belong to other countries (Malaysia, Indonesia and Taiwan).
For those who can count while reading the above, you might have noticed that the numbers don’t quite add up to 709. This is because there are species, as mentioned, that fall under several categories; some species are counted as both migrants as well as residents. Then there are also some species that were recorded in the Philippines previously, however no longer do, and are now extirpated in the country. Finally there are a few species of which we are unsure; they are not migratory species however there are historical records in the Philippines. In some cases these are records from places that are difficult to access and not often visited; we cannot discount that they might still be there.
Threatened species of the Philippines
A relatively large number of bird species in the Philippines, 97 at the moment, are listed as threatened under the IUCN Red List of species (www.redlist.org). Under the recently published DENR Red Data List this is even higher, 151 species. This is among other reasons because the DENR list reflects the status of the Philippine populations, while the IUCN takes a global approach. In other words, some bird species which are doing relatively well in other countries are also threatened in
the Philippines. As the DENR list has only been updated twice since 2004, we will use the IUCN data to give an indication of rising numbers of threat among birds. In table 3 we can see the number of threatened species (combination of categories Vulnerable, Endangered and Critically Endangered) as well as the individual threat levels, as listed in the consecutive checklists published by the Wild Bird Club of the Philippines over the years. As you can see the number of threatened species has gone up from 75 in 2009, to 97 in 2020. That is a 29% increase over just 11 years!
Out of the 10.945 bird species listed by IOC (v10.2), a total of 709 (6.5%) have been recorded in the relatively small country that is the Philippines, a staggering 241 of which are found nowhere else in the world. Unfortunately, deforestation and hunting are taking a heavy toll on these precious species, and 14% of our birds are in danger of extinction.
The Wild Bird Club of the Philippines is the main record keeping body for bird records in the Philippines, and has been publishing its results freely on their website for years. Visit it at www.birdwatch.ph. The above data was all collated from the annual checklists, mostly from the most recent version (2020) but also from historical checklists, all can be found on the site. Jensen, A., D. Allen, R. Hutchinson, C. Perez, W. van de Ven & JJ. Brinkman (2020): Checklist of birds of the Philippines. Wild Bird Club of the Philippines. www.birdwatch.ph