Ecological news and research

I have only just seen this research paper that was published last year, but I thought it was interesting enough to warrant posting.

Because of their large size and perceived need for large terrestrial prey, it has been thought that jaguars living in seasonally flooded rainforests in South America would seasonally migrate when water levels rose. But a study of jaguars living in Mamiraua Sustainable Development Reserve in central Brazil, using radio collars, has found they adopt a unique lifestyle in which they spend three to four months of the year as arboreal animals, only leaving to swim between tall trees.

During times when water levels were lower, jaguars fed predominantly on spectacled caimans and caiman eggs while during flood seasons they adapted to a diet of arboreal prey, primarily three-toed and two-toed sloths as well as howler, capuchin and squirrel monkeys and tamanduas. A female jaguar in the area was also recorded successfully weaning a healthy cub during the flood season.

This behaviour may explain the appearance of jaguars in floodplain forest habitat - the males are relatively small compared to those of other flooded environments like the Pantanal, probably because survival depends on them being small enough to easily climb. The findings could also change jaguar conservation, as many conservation plans have ignored floodplain forest because it was not believed to be suitable year-round habitat.

The full paper can be read here:
https://www.mamiraua.org.br/documentos/4efa9687760e6803157d98658b165b55.pdf
 
The first dedicated behavioural study of wild golden-bellied mangabeys, at Luikotale in Salonga National Park, has recorded high levels of predation on mammals. The group, consisting of 65 individuals (12 adult males, 30-40 adult females and subadult males and females and 15-25 juveniles) were followed for 46 days.

Over that research period, mangabeys killed and ate four duikers (probably all blue duiker) and an Alexander's cusimanse. At three of the kills, other mangabeys were seen begging for meat but on only one occasion was this successful.

Both red and blue duikers were seen following mangabeys (on 75 and 50% of tracking days), possibly benefiting from a reduced effort in searching for food. More research is needed to determine how duikers balance predation risk against possible social foraging benefits when feeding alongside mangabeys.

More research will also be needed to see if duiker predation is as consistent as was observed here - the mangabeys killed duikers at a similar rate (4 duikers over 46 days) to leopards in Tai National Park, Cote d'Ivoire (killed duikers at a rate of 1 every 10 days).

Information about the research project can be found here:
Research | Edward McLester

A PDF of the paper can be accessed via this page - it is the third link down:
Publications | Edward McLester
 
Research from central Africa has revealed how the two native wild cats of the area, the leopard and the African golden cat, may be the key to healthier forest regrowth.

The research was carried out at three sites - Nouabalé-Ndoki National Park in Republic of Congo, a sustainable logging concession just south of the national park and another certified logging concession in Cameroon. While both species of cat were present in the two Republic of Congo sites, they were absent from the Cameroon site because of hunting - while wildlife seemed more abundant at sustainably logged sites than intact ones, it all depended on them not being poached.

To determine how the cats affect the germination of trees, bottles of carnivore scent were hidden next to the seeds of an important timber tree species. This experiment was done at the Cameroonian site to ensure there was no scent pollution from real cats. The findings are still being analysed, but suggest that seeds at the scented stations survived and germinated more than those left exposed to seed predators without the carnivore scent.

More detailed information can be found in this article:
Elusive wildcats may hold the key to healthier forests in Africa

The unpublished abstract can be seen here:
ORBi: Detailled Reference
 
I have just seen this very interesting new discovery about the ecology of a little-known species of mammal, the mountain paca Cuniculus taczanowskii.

The scientists studying the animal first did a literature review into its diet and found that the species was recorded to mainly be herbivorous-frugivorous. However, a camera trapping study in the Madrigal del Podocarpus Reserve of southern Ecuador found that the mountain paca is actually an important scavenger in this ecosystem.

Chicken carcasses had been placed down in the forest to record the native scavenger community - it was found that mountain pacas fed from three of the chickens (11% of the carcasses used in the study), with one case of almost an entire chicken being consumed solely by mountain pacas over the course of six days. On some occasions, multiple individuals fed from a carcass simultaneously without conflict.

This discovery may make the mountain paca even more important to the montane forest ecosystem - as well as dispersing seeds, they could also remove a significant amount of carrion from the forest.

The full paper about the study can be seen here:
https://www.sciencedirect.com/science/article/pii/S2352249624000272#bb0050
 
I have seen three more recent scientific papers about species that serve as ecosystem engineers, which I will include here:

Brazilian bats
Research in Carajas National Forest in Brazil has found that enormous colonies of big naked-backed Pteronotus gymnonotus and Wagner's mustached bats Pteronotus personatus, over 150,000 individuals strong, has a big impact on the caves they roost in. The mineral-rich and acidic guano, when combined with percolating water, resulted in corrosion that enlarged the cave. Caves with either active bat colonies or evidence of inactive bat colonies were, on average, six times longer, had five times more area and a volume five times bigger than the regional average for bat-free caves. The amount of speleothems (mineral formations) were also more abundant, diversified and bigger in bat caves.
Bats as ecosystem engineers in iron ore caves in the Carajás National Forest, Brazilian Amazonia

Rufous-bellied woodpecker
Research in Nepal has indicated that this sap-feeding woodpecker can completely alter the shapes of the trees it feeds upon. This species taps trees, primarily oaks, birches, hollies and maples, with a series of small holes around the trunk in a ring shape. This resulted in the trees growing thicker bark around these rings, which are sap-rich and encourage the woodpeckers to tap them again. The result is trees with multiple rows of thick rings around their trunks. Some trees were left bent and deformed by repeated use by woodpeckers. As well as shaping the trees, the sap wells served as an attractant for insects such as bees, butterflies and ants, and sixteen other bird species were recorded drinking from them:
  • Darjeeling and crimson-breasted woodpeckers
  • Rufous sibia
  • White-browed and rufous-winged fulvettas
  • Hoary-throated barwing
  • Chestnut-tailed and blue-winged minlas
  • Buff-barred, lemon-rumped, ashy-throated and grey-hooded warblers
  • Green-backed and yellow-browed tits
  • White-tailed nuthatch
  • Green-tailed sunbird
Because the rufous-bellied woodpecker only fed from trees in intact forest, and are the only known sap-tapping woodpeckers from the Himalayan forest, they probably hold a uniquely important role in the local ecosystem and are suggested as being an ideal indicator species for the health of the environment.
View of Ecosystem engineering: Rufous-bellied woodpecker Dendrocopos hyperythrus (Vigors, 1831) modifying tree shapes of Himalayan broadleaved forests

Lesser Antillean iguana
Research on these critically endangered iguanas on the island of St. Eustatius has shown the other species that benefit from their nesting behaviour. These iguanas dig nesting burrows, some singular and others being communal warren-like nests with multiple tunnels and chambers that could extend to 1.5m underground. The most common species found using the study burrows was the red-faced ground lizard Pholidoscelis erythrocephalus, which also nests in the burrows and may also have been foraging for both iguana eggs and tarantulas. A red-bellied racer snake Alsophis rufiventris, a known predator of ground lizards and their eggs, was also seen entering an iguana nest. Among invertebrates, species found in iguana nests included tarantulas, crickets*, ants, a land crab and a giant centipede. The nests, with their eggshells or unhatched eggs, also make an ideal growth medium for plants, and one nest had the roots of a nearby tree growing through a pile of old and decomposing eggs. The chances are high that, because of the limited number of nests observed, lesser Antillean iguana nests host even more species.
https://www.researchgate.net/public...catissima_Laurenti_1768_as_ecosystem_engineer

* Although the paper mentions the cricket as being the invasive tropical house cricket, Gryllodes sigillatus, the photograph of the cricket in the paper does not look like that species and, to me, looks more like a species of camel cricket.
 
Here's something recently discovered that I didn't expect - Ethiopian wolves may be pollinators. Researchers in the Bale Mountains recorded wolves making repeated visits to the blooms of Ethiopian red hot pokers Kniphofia foliosa, and licking nectar from the flowers. In the process, their muzzles were seen to become coated in pollen. Sometimes the wolves could visit up to thirty flowers in a single foraging session. In addition, researchers recorded wolves from at least three different packs feeding from the flowers, indicating that this may be a widespread behaviour in the species. Ethiopian wolves are the only canid and the only large carnivore so far recorded to feed on nectar.

An article can be found in this link:
Ethiopian Wolves Become First Large Carnivore Documented Feeding on Nectar | Sci.News

The scientific paper can be found here:
https://esajournals.onlinelibrary.wiley.com/doi/full/10.1002/ecy.4470
 
An interesting study has recently been published, looking at the role that three species of lizard from the dry forests of Ankarafantsika National Park, Northwestern Madagascar, can play in seed dispersal. The three lizards in question were the Oustalet's chameleon, Cuvier's Madagascar swift and Western girdled lizard.

As part of the study, a total of 89 chameleons, 254 swifts and 38 girdled lizards were captured so that their faeces could be examined. Altogether, 24.7% of chameleons, 20.1% of swifts and 15.8% of girdled lizards passed seeds in their droppings. The chameleon and girdled lizard each consumed fruits from 8 species of plant, while the swifts fed from 18 species. Some of the species of plant showed high levels of germination - over fifty percent of seeds - having passed through these lizards. All three lizard species also fed on a different range of fruits to those eaten by the common brown lemur, another local seed disperser.

These three lizard species may be important seed dispersers in their habitat, and could also be useful for reforesting degraded land - all three species can survive in fragments of forest too small for larger seed dispersers such as lemurs.

The abstract for the paper can be read here.

An article about the research can be read here.
 
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