Podcast : Introductions

Why Conservation matters?

This text, including abstracts from scientific papers and pictures found here are supposed to illustrate what is being discussed in the trailer-why conservation matters?

Current extinction rates and loss of biodiversity is outstandingly high and is accelerating directly or indirectly from human activities. The role of human actions, which include biological impoverishment, habitat fragmentation, climate change, increasing toxification, and the rapid global movement of people, brings new escalating conservation challenges and emerging diseases. Unfortunately, this pressure impairs long-term survival of threatened free-ranging and captive wildlife species, while having hazardous effects on ecosystems and public health.

Our health, food and security depend on biodiversity. From medical treatments to food production, biodiversity is critical to society and people’s well-being. Of all the plant, amphibian, reptile, bird and mammal species that have gone extinct since AD 1500, 75% were harmed by overexploitation or agricultural activity or both.

All our economic activity ultimately depends on nature. It’s estimated that, globally, nature provides services worth around US$125 trillion a year .

Stable planetary systems have enabled modern human society to develop. Without healthy natural systems researchers are asking whether continuing human development is possible.

Five main categories of threats leading to biodiversity loss and ecosystem destruction include:

HABITAT LOSS AND DEGRADATION

Habitat loss and fragmentation

OVEREXPLOITATION

Cetacean entanglement

Illegal wildlife trade

CLIMATE CHANGE

INVASIVE SPECIES

POLLUTION

Aquatic pollution

Poisoning Vultures – 2 exemples: cyanide and diclofenac

In this post we will illustrate 3 of them: habitat loss and degradation, overexploitation through poaching and pollution.

POLLUTION

1. Aquatic pollution

Oil and Sea Turtles presents a basic overview of sea turtle biology, summarizes what is known about the effects of oil on sea turtles, reviews potential response actions in the event of a release, and presents case histories from previous spills.

This guidance document (see below) is the third in a series of publications prepared by NOAA’s Office of Response and Restoration to provide response-related information on specific warm-water resources. https://response.restoration.noaa.gov/oil-and-chemical-spills/oil-spills/resources/oil-and-sea-turtles.html

Cetaceans have been recognized as suitable bioindicators to monitor the health of aquatic ecosystems (Bossart 2011). They are telling us, human what is being poured into the Oceans. They are indicators of the ocean’s health, meaning our own health as we, human are using ocean ressources in many aspects of our lives.

Cetaceans are another species to be affected by oil spill. Check out this paper about a large Unusual Mortality Event (UME) coinciding with the Deepwater Horizon (DWH) oil spill. « The DWH is the largest marine-based spill in U.S. history. During and following the DWH oil spill, significantly elevated polycyclic aromatic hydrocarbon (PAH) levels attributed to this spill were detected in coastal Golf of Mexico waters, including Louisiana, Mississippi, and Alabama »

Adrenal Gland and Lung Lesions in Gulf of Mexico Common Bottlenose Dolphins (Tursiops truncatus) Found Dead following the Deepwater Horizon Oil Spill. 2015. PLoS ONE 10(5): e0126538. doi:10.1371/journal. pone.0126538

A northern Gulf of Mexico (GoM) cetacean unusual mortality event (UME) involving primarily bottlenose dolphins (Tursiops truncatus) in Louisiana, Mississippi, and Alabama began in February 2010 and continued into 2014. Overlapping in time and space with this UME was the Deepwater Horizon (DWH) oil spill, which was proposed as a contributing cause of adre- nal disease, lung disease, and poor health in live dolphins examined during 2011 in Barataria Bay, Louisiana. To assess potential contributing factors and causes of deaths for stranded UME dolphins from June 2010 through December 2012, lung and adrenal gland tissues were histologically evaluated from 46 fresh dead non-perinatal carcasses that stranded in Louisiana (including 22 from Barataria Bay), Mississippi, and Alabama. UME dolphins were tested for evidence of biotoxicosis, morbillivirus infection, and brucellosis. Results were compared to up to 106 fresh dead stranded dolphins from outside the UME area or prior to the DWH spill. UME dolphins were more likely to have primary bacterial pneumonia (22% compared to 2% in non-UME dolphins, P = .003) and thin adrenal cortices (33% compared to 7% in non-UME dolphins, P = .003). In 70% of UME dolphins with primary bacterial pneumonia, the condition either caused or contributed significantly to death. Brucellosis and morbillivirus infections were detected in 7% and 11% of UME dolphins, respectively, and biotoxin levels were low or below the detection limit, indicating that these were not primary causes of the current UME. The rare, life-threatening, and chronic adrenal gland and lung diseases identified in stranded UME dolphins are consistent with exposure to petroleum compounds as seen in other mammals. Exposure of dolphins to elevated pe- troleum compounds present in coastal GoM waters during and after the DWH oil spill is proposed as a cause of adrenal and lung disease and as a contributor to increased dolphin deaths.

What are PCBs?-PCBs or polychlorinated biphenyls https://www.epa.gov/pcbs/learn-about-polychlorinated-biphenyls-pcbs

PCBs belong to a broad family of man-made organic chemicals known as chlorinated hydrocarbons. PCBs were domestically manufactured from 1929 until manufacturing was banned in 1979. They have a range of toxicity. Due to their non-flammability, chemical stability, high boiling point and electrical insulating properties, PCBs were used in hundreds of industrial and commercial applications including:

• Electrical, heat transfer and hydraulic equipment
• Plasticizers in paints, plastics and rubber products
• Pigments, dyes and carbonless copy paper
• Other industrial applications

PCBs are persistent and still found in the environment, especially in the aquatic environment where they bioaccumulate along the food chain… Humans are part of this food chain!!! Scary?

PCBs have been demonstrated to cause a variety of adverse health effects. Their effects are numerous, including cancer in animals such as belugas: https://www.scientificamerican.com/article/cancer-wildlife-environmental-contaminant

See also:

Pathology and toxicology of beluga whales from the St. Lawrence Estuary, Quebec, Canada. Past, present and future. Sci Total Environ. 1994. 154(2-3):201-15.

An indigenous population of 450-500 beluga whales (Delphinapterus leucas) inhabiting the St. Lawrence Estuary has been exposed chronically for more than 50 years to a complex mixture of industrial pollutants including organochlorinated compounds (OC), polycyclic aromatic hydrocarbons (PAH) and heavy metals. From 1983 to 1990, we have necropsied 45 well preserved carcasses out of a total of 120 beluga whales reported dead over this period. Of these 45 animals, nine were affected by 10 malignant neoplasms. Fifteen animals (33%) were affected by pneumonia. Milk production was compromised in eight of 17 mature females (41%), by inflammatory changes (seven animals) and cancer (one animal) which affected the mammary glands. Opportunistic bacteria were found in pure culture, and/or in significant amounts in at least two organs in 20 belugas (44%). The concentrations of both total PCBs and highly chlorinated PCB congeners were much higher in St. Lawrence animals than in Arctic beluga whales. OC-induced immunosuppression has been repeatedly demonstrated in a wide variety of animal species. Therefore, it is probable that the immune functions of St. Lawrence beluga whales are impaired. Benzo[a]pyrene adducts were detected in 10 of the 11 St. Lawrence beluga whales of which tissues (six livers, 10/11 brains) were analyzed by a method based on HPLC. No such adducts were found in four Arctic animals. Since benzo[alpha]pyrene is one of the most potent chemical carcinogens known to man, these compounds might be responsible for some of the cancers observed in that population. Overall, our findings contrast vividly with those of others who found that cancers are exceedingly rare in free-ranging odontocete populations and that the major causes for mortalities in these populations are bacteria, parasites, and trauma.

Other effects on animals include the immune system, reproductive system, nervous system, endocrine system and other health effects. Studies in humans support evidence for potential carcinogenic and non-carcinogenic effects of PCBs. The different health effects of PCBs may be interrelated. Alterations in one system may have significant implications for the other systems of the body.

PCB pollution continues to impact populations of orcas and other dolphins in European waters. Nature.com Scientific RepoRts 2016 | 6:18573 | DOI: 10.1038/srep18573

Organochlorine (OC) pesticides and the more persistent polychlorinated biphenyls (PCBs) have well-established dose-dependent toxicities to birds, fish and mammals in experimental studies, but theactual impact of OC pollutants on European marine top predators remains unknown. Here we show that several cetacean species have very high mean blubber PCB concentrations likely to cause population declines and suppress population recovery. In a large pan-European meta-analysis of stranded (n = 929)or biopsied (n = 152) cetaceans, three out of four species:- striped dolphins (SDs), bottlenose dolphins(BNDs) and killer whales (KWs) had mean PCB levels that markedly exceeded all known marine mammal PCB toxicity thresholds. Some locations (e.g. western Mediterranean Sea, south-west Iberian Peninsula) are global PCB &laquohotspots&raquo for marine mammals. Blubber PCB concentrations initially declined following a mid-1980s EU ban, but have since stabilised in UK harbour porpoises and SDs in thewestern Mediterranean Sea. Some small or declining populations of BNDs and KWs in the NE Atlantic were associated with low recruitment, consistent with PCB-induced reproductive toxicity. Despite regulations and mitigation measures to reduce PCB pollution, their biomagnication in marine foodwebs continues to cause severe impacts among cetacean top predators in European seas.

2. Poisoning Vultures – 2 exemples: cyanide and diclofenac

a. Cyanide poisoning

Ivory poachers and poison: drivers of Africa’s declining vulture populations. Oryx, 2016, 50(4), 593-596 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/1BC7E51B8795739FE0149B282678E255/S0030605315001209a.pdf/ivory_poachers_and_poison_drivers_of_africas_declining_vulture_populations.pdf

Four species of African vultures have been recategorized as Critically Endangered, and two as Endangered, on the IUCN Red List. Their declining status is attributed partly to the impacts of widespread poisoning. Prior to 2012 poisoning of vultures was mostly associated with illegal predator control by livestock farmers, in which vultures were typically unintended victims. More recently, ivory poachers have been using poisons to kill elephants Loxodonta africana or to contaminate their carcasses specifically to eliminate vultures, whose overhead circling might otherwise reveal the poachers’ presence. Between 2012 and 2014 we recorded 11 poaching-related incidents in seven African countries, in which 155 elephants and 2,044 vultures were killed. In at least two incidents the harvesting of vulture body parts (for fetish) may have provided an additional motive. We show that vulture mortality associated with ivory poaching has increased more rapidly than that associated with other poisoning incidents, and now accounts for one-third of all vulture poisonings recorded since 1970. This recent surge in the illegal use of poisons exposes weaknesses in the regulations, for which we propose measures aimed primarily at retail controls. However, because ivory poachers already operate outside any legal framework, African governments require international support in applying more punitive sentencing against mass wildlife poisoning.

News from 2017 can be found here: https://www.voanews.com/africa/poachers-target-africas-lions-vultures-poison

b. Diclofenac poisoning

Diclofenac is an anti-inflammatory drug used in cattle since 2013 (approved for veterinary use in Spain). This drug is highly toxic to vultures of the genus Gyps who may consume it via dead cows. According to Rhys Green, a conservation scientist at the University of Cambridge, UK, the drug could cause populations of that country’s Eurasian griffon vultures (Gyps fulvus) to decline by between 1-8% each year.

Diclofenac is widely available in Asia. Since 1990, it has been the cause of decline of at least 96% for white-backed vultures (Gyps africanus) and 92% each for the long-billed vultures (G. indicus) and slender-billed vultures (G. tenuirostris). We know now that their death is associated with visceral gout (tubular necrosis with uric acid deposition in the kidney and other tissues) and consequently renal failure. There is no significant inflammation and experiments demonstrated a dose dependent toxicity. 

Diclofenac was banned in 2006 in India, then Nepal and Pakistan. It is still available in many European countries.…

OVEREXPLOITATION

3. Cetacean entanglement

Global marine mammal bycatch rates are estimated to exceed 650 000 animals annually (Read et al. 2006), a large proportion of which are discarded. 

The effect that entanglements can have on cetaceans is a concern worldwide. Most marine mammals, including cetaceans (whales and dolphins) and pinnipeds (seals and fur seals) are at risk from entanglements; as a result of rubbish, marine debris or marine industry activities.

Some large whale species (humpback whales and right whales) which make annual migrations are still making a gradual recovery from the impacts of whaling in the last century.

This recovery has coincided with a growth in coastal development, fishing activities, aquaculture and other off shore infrastructure. Much of this activity is within the migratory paths of these marine mammals. Reports of whale entanglements have been reported on the increase throughout the world.

Check out this paper (below) about bycatch and entanglement records across Australia with 1987 cases collected from 1987 to 2016. Since 2000 there has been a substantial increase in reported bycatch and entanglements. The marine mammal center, based in Sausalito (CA, USA) is a rehabilitation center, that rescues and treats and releases disabled marine mammals mostly pinnipeds. Please check out their webpage about entangled animals and disentanglements: https://www.marinemammalcenter.org/Get-Involved/awareness-campaigns/our-entangled-patients.html

Long-term trends and a risk analysis of cetacean entanglements and bycatch in fisheries gear in Australian waters. Biodiversity and Conservation volume 29, pages251-282(2020)

Assessments of fisheries interactions with non-target species are crucial for quantifying anthropogenic threatening processes and informing management action. We perform the first multi-jurisdictional analysis of spatial and temporal trends, data gaps and risk assessment of cetacean interactions with fisheries gear for the entire Australian Exclusive Economic Zone. Bycatch and entanglement records dating from 1887 to 2016 were collected from across Australia (n=1987). Since 2000 there has been a substantial increase in reported bycatch and entanglements and this is likely the result of improved monitoring or recording by some jurisdictions and fisheries as well as changing fishing effort, combined with continuing recovery of baleen whale populations after cessation of commercial whaling. A minimum of 27 cetacean species were recorded entangled, with over 30% of records involving interactions with threatened, vulnerable or endangered species. Three times the number of dolphins and toothed whales were recorded entangled compared to baleen whales. Inshore dolphins were assessed as most vulnerable to population decline as a result of entanglements, though humpback whales, common bottlenose dolphins, and short-beaked common dolphins were the most frequently caught. Only one-quarter of animals were reported to have survived entanglement, either through intervention or self-release from fishing gear. Spatial mapping of the records highlighted entanglement hotspots along the east and west coast of the continent, regions where high human population density, high fishing effort, and high density of migrating humpback whales all occur, augmented by high captures of dolphins in shark control gear along the east coast. Areas of few entanglements were more remote, highlighting substantial bias in entanglement reporting. Our gap analysis identified discrepancies in data quality and recording consistency both within and between jurisdictions. Disparities in the types of fisheries data provided for the analysis by different state agencies limited our ability to compile bycatch data in a representative and systematic way. This research highlights the need for improved standardised data recording and reporting by all agencies, and compulsory sharing of detailed fisheries interaction and effort data, as this would increase the value of entanglement and bycatch data as a conservation and management tool.

Entanglement in fishing gear is a major cause of morbidity and mortality in large whales. In the North Atlantic right whale (Eubalaena glacialis) these events have been shown to result in outcomes that range from transient to persistent entanglements. These wounds can evolve on the long term (years), or result in death after about 6 mo. Examination of entanglement mortalities has shown a variety of chronic impacts for persistent terminal entanglements (Moore et al. 2004). Recent measures to reduce the impact of entanglement in the US includes requirements for weak links on buoy lines and sinking ground lines between fishing traps and pots (U.S. Federal Register 2007). Disentanglement continues to be one option until effective preventative measures are developed, but many efforts are unsuccessful and there is no means of controlling the time between an entanglement and its first discovery by responders.

Rope trauma, sedation, disentanglement, and monitoring-tag associated lesions in a terminally entangled North Atlantic right whale (Eubalaena glacialis). MARINE MAMMAL SCIENCE, 29(2): E98-E113 (April 2013)

A chronically entangled North Atlantic right whale, with consequent emaciation was sedated, disentangled to the extent possible, administered antibiotics, and satellite tag tracked for six subsequent days. It was found dead 11 d after the tag ceased transmission. Chronic constrictive deep rope lacerations and emaciation were found to be the proximate cause of death, which may have ultimately involved shark predation. A broadhead cutter and a spring-loaded knife used for disentanglement were found to induce moderate wounds to the skin and blubber. The telemetry tag, with two barbed shafts partially penetrating the blubber was shed, leaving barbs embedded with localized histological reaction. One of four darts administered shed the barrel, but the needle was found postmortem in the whale with an 80degree bend at the blubber-muscle interface. This bend occurred due to epaxial muscle movement relative to the overlying blubber, with resultant necrosis and cavitation of underlying muscle. This suggests that rigid, implanted devices that span the cetacean blubber muscle interface, where the muscle moves relative to the blubber, could have secondary health impacts. Thus we encourage efforts to develop new tag telemetry systems that do not penetrate the subdermal sheath, but still remain attached for many months.

Consequences of injuries on survival and reproduction of common bottlenose dolphins (Tursiops truncatus) along the west coast of Florida. 2008 Marine Mammal Science 24(4):774 – 794

Accurate identification of human-induced injuries that lead to death or interfere with reproduction is important for marine mammal management, as deaths exceeding established limits can lead to restrictions on fisheries or vessel operations. The fates of cetaceans last seen swimming with attached gear, particularly in pelagic fisheries, or with vessel strike lacerations, have been difficult to predict. Survival and reproduction data from long-term research on resident common bottlenose dolphins near Sarasota, Florida were examined relative to consequences of fishing gear ingestion, line entanglements, vessel strikes, and amputations of unknown origins. Fishing hooks embedded in the throat, goosebeak, or esophagus, or line wrapped around the goosebeak, generally lead to death. Multiple, constrictive line wraps around fin insertions can lead to amputation, blood loss, impaired mobility, or infection. Dolphins with ingested gear or severe entanglements may swim away with the gear, but likely die later. Propeller injuries involving only soft tissue were often survivable. Some dolphins survived amputations of the distal ends of fins, and continued to reproduce. As a precautionary approach, dolphins with ingested gear or severe constrictive entanglements should be considered mortalities, but extrapolations of findings from coastal bottlenose dolphins to other cetaceans and different gear must be done with caution.

4. Illegal wildlife trade

UNITED NATIONS OFFICE ON DRUGS AND CRIME (UNODC)

UNODC is a global leader in the struggle against illicit drugs and international crime, and the lead United Nations entity for delivering legal and technical assistance to prevent terrorism. 

« Wildlife crime worth USD 8-10 billion annually, ranking it alongside human trafficking, arms and drug dealing in terms of profits »: from UNODC chief 2014 https://www.unodc.org/unodc/en/frontpage/2014/May/wildlife-crime-worth-8-10-billion-annually.html

For the following section, see UNODC, World Wildlife Crime Report: Tracking in protected species, 2016 for complete information.

a. Poaching: African elephant ivory– ART, DÉCOR, AND JEWELLERY

There are about half a million elephants left in Africa,  although their numbers is uncertain. Based on the most recent stimates (2013), over 60% of the known and probable populations of African elephants reside in just three countries: Botswana, Zimbabwe and the United Republic of Tanzania. 

Based on DNA samples, PIKE scores and the seizure records, most of the ivory supply appears to be coming from countries at peace, such as the United Republic of Tanzania and to a lesser extent, Kenya, Mozambique, and Central Africa. Two reserves in The United Republic of Tanzania have been the main sources of ivory tracked internationally in recent years: the Selous Mikumi/Niassa Ecosystem (until 2013) and the Ruaha Rungwa Ecosystem (from 2013) .

A second source of this ivory emanates from Western Africa, with seizures associated with departures from Nigeria and Togo. Much of this ivory comes from Central Africa, particularly Cameroon, Gabon, and the Republic of the Congo. The main mechanism of international transport appears to be containerised sea freight. Based on the seizure records, key transit countries for containerised tracking include Malaysia (particularly Port Klang), Viet Nam (particularly Da Nang and Hai Phong), Nigeria, Uganda, Togo, the United Arab Emirates, and Singapore. 

One of the most remarkable facets of the illegal ivory trade is the amount of contraband seized. Every year, law enforcement authorities in Africa and Asia make large ivory seizures, many measuring over 500 kg.

The CITES Elephant Trade Information System (ETIS) collects ivory seizure data from CITES parties. Between 2009 and 2014 ETIS has recorded 91 such shipments, totalling 159 metric tons of ivory. This represents ivory from at least 15,900 elephants. The largest national destination market for detected ivory shipments appears to be China (ETIS). World WISE documents over 800 raw ivory seizures between 2006 and 2015, for a total of just under 123 metric tons of ivory. For those seizures where the destination of the ivory was reported (104 metric tons), about 40% (42 metric tons) were directly destined for China and at least two-thirds of the ivory seized is destined for East Asian markets.

Another venue for illicit retail sales is the internet, including the dark web, and a number of studies have monitored on-line sales of alleged ivory products.

b. Poaching: Pangolin – FOOD, TONICS, AND MEDICINES

The use of wildlife as food and the use of wildlife as medicine are closely related, because in some countries, there is a persistent belief that consumption of wild products is benecial for health. 

There are eight species of pangolins,four species in Africa and four species in Asia. Of the four Asian pangolin species,two are classied as &laquoCritically Endangered&raquo, and two as &laquoEndangered&raquo by the IUCN. All four African species are classied as &laquoVulnerable&raquo by the IUCN. They have been consumed traditionally as food in both regions, and their scales are also used in traditional medicine.

Pangolins are dicult to breed and mortality rates amongst pangolins in captivity is known to be very high. Aside from a few zoos, there are no known captive breeding facilities for any pangolin species.

Pangolin scales, is used in traditional medicine in both Africa and Asia. In Africa, particularly West Africa, they are used to treat a wide range of physical and spiritual maladies. In Asia, whole scales are sold, raw or fried, from traditional medicine retailers.

These scales have multiple uses in traditional medicine: to cure skin diseases, improve blood circulation, and to stimulate milk production in lactating women. In illegal trade, however, some 20 metric tons of scales are documented in World WISE between 2007 and 2015, equivalent to about 54,000 live pangolins. Between 2007 and 2015, pangolins destined for culinary use accounted for about 55,000 pangolins.

 Asian countries were the source of the bulk of all the pangolin products seized, although Uganda and other African countries accounted for 20% of all seizures. Many of the seized pangolin scales originating from Africa were found in mixed consignments, alongside rhino horn or ivory. Most (92%) of these shipments were destined for China or Viet Nam.

c. Poaching: Rhinoceros – FOOD, TONICS, AND MEDICINES

Rhino horn is made from keratin and has NO medicinal properties.

Rhino horn has historically been used in traditional medicine in Asia to treat fever and cerebrovascular disease. More recently, it is used in treating other ailments, from hangovers to cancer. The prices that it currently commands (the tens of thousands of dollars /kg) – are disproportionate to any medical utility it might have.

The present rhino population is a fraction of what there once was. Asrecently as 1960, there were estimated to be 100,000 black rhinos in Africa. Due to heavy poaching from the late 1970s through the mid-1990s, there are less than 5,000 black rhinos today. Indeed, there are less than 28,000 rhinos of any species left in Africa and Asia. About 70% of the remaining population are southern white rhinos living in the eastern provinces of South Africa.

Demand for this horn has grown greatly over the past 10 years, driving an escalating wave of poaching. In 2014, most (94%) of the poaching in Africa took place in South Africa, and most (68%) of the rhinos poached in South Africa were taken from Kruger National Park, which is contiguous with Limpopo National Park in Mozambique. According to World WISE, in order of importance, South Africa, Mozambique, Zimbabwe and Kenya are the main sources of seized shipments.

The United Arab Emirates and European countries (including Slovakia, the Czech Republic, Belgium, Italy and Germany) are indicated as transit countries.

The most important destination countries are Viet Nam, followed by China. Other countries include Ireland, Czech Republic, The United States and Thailand.

HABITAT LOSS AND DEGRADATION

5. Habitat fragmentation and destruction: the orang-utan.

Agriculture is a leading cause of deforestation globally and, this is likely to get worse with increasing demands for food and commodities. Inevitably, deforestation leads to losses of biodiversity and ecosystem services (Chapin Iii et al., 2000). Southeast Asia has experienced some of the highest deforestation rates in the world (Hansen et al., 2013), especially in Borneo, Sumatra and Peninsular Malaysia, which, between 2000 and 2010 lost roughly 11% of their lowland forests and 20% of peatswamp forest (Miettinen, Shi, & Liew, 2011).

Forests have been cleared for commercial plantations (rubber, timber, and fast-growing trees for the pulp and paper industry), but clearance for oil palm (Elaeis guineensis) has been particularly extensive over the last 20 years (Gaveau et al., 2016).

Orang-utans (Pongo spp.) are the only non-human great ape found outside Africa. All three species of orang-utans are Critically Endangered on the IUCN Red List of Threatened Species (IUCN, 2017). Habitat loss, fragmentation, and hunting continue to be leading contributors of population decline (Meijaard et al., 2011; Voigt et al., 2018; Wich et al., 2016).

Orang-utan dietary and behavioral ecology makes these species highly adapted to tropical forests, where they prefer moving through areas of uniform canopy height, avoiding forest gaps (Felton, Engström, Felton, & Knott, 2003). Although orang-utans will readily move on the ground through areas of oil palm, most observations in oil palm (nests or signs of feeding) are within 50 m of forest areas (Ancrenaz et al., 2015). Three-dimensional structural features of the canopy are likely to be important determinants of orang-utan presence.

Currently, the highest densities of orang-utans in Borneo are in the lowland natural forests lower than 500m above sea level (Voigt et al., 2018), which are the same suitable for agriculture. This situation leads to high levels of deforestation and forest degradation within the orang-utan range (Santika et al., 2017).

Recent studies from Kalimantan (Indonesia) suggest that human-orangutan conflict and its related killings increase with proximity to newly converted forest to industrial agriculture (Meijaard, et al. 2011- Quantifying killing of orangutans and human-orangutan conflict in Kalimantan, Indonesia. PLoS One). Village communities tend to hunt orangutans for bushmeat, which increases with a decrease in forest cover surrounding the village and an increase in area for agriculture in the village but a decrease in income from this sector.

Densities of Bornean orang-utans (Pongo pygmaeus morio) in heavily degraded forest and oil palm plantations in Sabah, Borneo. Am J Primatol. 2019;81:e23030.

The conversion of forest to agriculture continues to contribute to the loss and fragmentation of remaining orang-utan habitat. There are still few published estimates of orang-utan densities in these heavily modified agricultural areas to inform range-wide population assessments and conservation strategies. In addition, little is known about what landscape features promote orang-utan habitat use. Using indirect nest count methods, we implemented surveys and estimated population densities of the Northeast Bornean orang-utan (Pongo pygmaeus morio) across the continuous logged forest and forest remnants in a recently salvage-logged area and oil palm plantations in Sabah, Malaysian Borneo. We then assessed the influence of landscape features and forest structural metrics obtained from LiDAR data on estimates of orang-utan density. Recent salvage logging appeared to have a little short-term effect on orang-utan density (2.35ind/km2), which remained similar to recovering logged forest nearby (2.32 ind/km2). Orang-utans were also present in remnant forest patches in oil palm plantations, but at significantly lower numbers (0.82 ind/km2) than nearby logged forest and salvage-logged areas. Densities were strongly influenced by variation in canopy height but were not associated with other potential covariates. Our findings suggest that orang-utans currently exist, at least in the short-term, within human-modified landscapes, providing that remnant forest patches remain. We urge greater recognition of the role that these degraded habitats can have in supporting orang-utan populations, and that future range-wide analyses and conservation strategies better incorporate data from human-modified landscapes.

Despite pledges by the Indonesian and Malaysian government to stabilize orang-utan populations, they have continued to decline by 25% over the past 10 years (Santika et al., 2017). Our results show forest conversion to oil palm negatively affects orang-utan populations, leading to reduced densities. The presence of orang-utans within oil palm estates demonstrates that these great apes may have greater ecological resilience to disturbance than previously assumed. Although forest patches alone cannot maintain viable populations, if managed appropriately, they may act as important corridors or stepping-stones, connecting isolated populations, and facilitate migration in response to climate change. As orang-utan habitats are the most suitable areas for oil palm production in Borneo and Sumatra, these modified landscapes should be taken more seriously in orang-utan conservation and monitoring efforts.

First integrative trend analysis for a great ape species in Borneo. Am J Primatol. 2019;81:e23030.

For many threatened species the rate and drivers of population decline are di cult to assess accurately: species’ surveys are typically restricted to small geographic areas, are conducted over short time periods, and employ a wide range of survey protocols. We addressed methodological challenges for assessing change in the abundance of an endangered species. We applied novel methods for integrating eld and interview survey data for the critically endangered Bornean orangutan (Pongo pygmaeus), allowing a deeper understanding of the species’ persistence through time. Our analysis revealed that Bornean orangutan populations have declined at a rate of 25% over the last 10 years. Survival rates of the species are lowest in areas with intermediate rainfall, where complex interrelations between soil fertility, agricultural productivity, and human settlement patterns influence persistence. These areas also have highest threats from human-wildlife conflict. Survival rates are further positively associated with forest extent, but are lower in areas where surrounding forest has been recently converted to industrial agriculture. Our study highlights the urgency of determining speci c management interventions needed in di erent locations to counter the trend of decline and its associated drivers.

• Pressure on orang-utan populations in the same period of time varied substantially among regions: high pressure in West and Central Kalimantan.
• Co-occurrence of orangutan populations with areas most suitable for human activities has led to an enhanced risk of human-wildlife conflicts.