During my times as a Master’s student at the University of Helsinki I visited Madagascar for a month and a half. Conducting my thesis fieldwork in Ranomafana National Park allowed me to get in close contact with the unique, highly threatened diversity of the island. As a side project in collaboration with my current PhD directors, I installed different camera-traps in the forest and baited them with carcasses. The community of vertebrate scavengers on the island was virtually unknown, other than the fact that no obligate scavengers (i.e., vultures) are known in Madagascar. Our research provided a first insight to the scavengers of the island, and has recently been published (link to the article here).
Different animals walking past triggered the camera sensors. This included different abundant birds, such as Madagascar magpie-robin (Copsychus albospecularis), red fody (Foudia madagascarensis) or Malagasy brush-warbler (Nesillas typica). However, the most exciting avian find was a Madagascar ibis (Lophotibis cristata), a bird foraging on the ground in Talatakely area. Incredibly, I managed to glimpse this mythical endemic on the following day, when I walked the area with my guide to retrieve the cameras.
In that same area, Talatakely, I heard strange calls as I finished installing the last camera-trap of the day, among the ubiquitous Madagascar cuckoos (Cuculus rochii), cuckoo-rollers (Leptosomus discolor) and souimanga sunbirds (Cinnyris sovimanga). I backed up and waited for a bit, my guides and assistants heading back to the headquarters as a storm was looming.
I had just passed an old pitta-like ground-roller (Atelornis pittoides) nest next to the trail, but I couldn’t believe my eyes when I spotted a brilliant adult calling from some open logs. This shy but gorgeous endemic usually barks from the understory, but that time delivered some sort of an alarm call, different from their usual song. All covered in goosebumps after my best observation ever of this stunner, I noticed two ring-tailed vontsiras (Galidia elegans) in the understory apparently within the territory of the ground-roller, causing all the hubbub. The mongooses eventually ran away in the direction of the carrion I had just installed.
My survey only found mammals and no other vertebrates feeding on carcasses during the first 24 hours. The diversity and density of large invertebrates feeding on them was astonishing, some of which showing up almost instantaneously at carcass deployment site. Given that I only had limited resources for this side project, surveying carcass consumption only during the first 24 hours seemed like a good compromise. Although I mostly focused on primary consumption, I registered a red-fronted coua (Coua reynaudii) feeding on a large arthropod on a carcass site. Birds and other animals are known to use carcasses as a source for preys, what we know as secondary consumption of carrion. Besides, capturing this endemic was great, as I only managed to properly see it a couple of times during my stay.
Among the scavenger mammals, I found both native and exotic species. Ring-tailed vontsiras and Malagasy civets (Fossa fossana) belong to an endemic family of carnivores and showed up in different carcasses within the National Park. Although threatened and very elusive, I managed views of both. The Malagasy civet (locally known as “fanaloka“) visited the camp at night in Vatoharanana, where we stayed some days to collect samples and survey scavengers in the middle of the rainforest.
A key result of our research relates to the role of protected areas in Madagascar. We only encountered native, endemic scavengers in the primary forest areas surveyed inside the National Park. However, secondary forests surveyed just outside the protected area only featured exotic scavengers, including the domestic cat (Felis catus) and the black rat (Rattus rattus). The ecological process of carrion removal by scavengers is maintained by a community assembled with native species only in the best-preserved habitats, and these lie in protected areas in Madagascar. As exotic species may dispatch native ones outside of the National Park, the whole community assemblage changes and carrion removal lies to exotic, generalist species.
On our days in Vatoharanana camp, we also connected with different endemic rodents. One of them was tentatively identified as a Tanala tufted-tailed rat (Eliurus tanala), a small arboreal mouse which sat quietly on a low branch during a night walk. The other one, most likely an eastern red forest rat (Nesomys rufus), foraged in a carcass site at midday while we approached it for camera retrieval. Both belong to a Madagascar-endemic group of rodents, traditionally known to feed exclusively on vegetables. However, we found tufted-tailed rats feeding at carcass sites (whether primarily or secondarily could not be determined), and hypothesized red forest rats might also exploit carcasses for food.
This first record of animal protein consumption showcases the poor knowledge of the diet of Madagascar endemic mammals. These results are only the tip of the iceberg, as this is the first contribution to the role of vertebrates and invertebrates in carrion removal at Madagascar tropical rainforests, to our understanding. Scavenging is a key ecological process that could be affected by the numerous conservation impact drivers of Madagascar.
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