News Article | September 13, 2016
A study, by San Diego Zoo Global conservationists, released this week (Sept. 12, 2016) is shedding new light on how scientists evaluate polar bear diet and weight loss during their fasting season. On average, a polar bear loses up to 30 percent of its total body mass while fasting during the open-water season. Although some scientists previously believed land-based foods could supplement the bears' nutritional needs until the sea ice returns, a new study published in the scientific journal Physiological and Biochemical Zoology has revealed that access to terrestrial food is not sufficient to reduce the rate of body mass loss for fasting polar bears. The study—undertaken by Manitoba Sustainable Development, the University of Alberta, and Environment and Climate Change Canada—weighed polar bears that were detained in the Polar Bear Holding Facility in Churchill, Manitoba, Canada from 2009 to 2014. Polar bears were kept in this facility as part of the Polar Bear Alert Program, which aims to reduce conflict between humans and polar bears around the town of Churchill. To prevent habituation, polar bears are not fed while in the facility, which allowed for a controlled measure of their weight loss. On average, polar bears lost 2.2 pounds (1 kilogram) of mass per day—exactly the same amount as free-ranging bears measured during the ice-free season on the coastline of Hudson Bay. Scientists reported that even with land-based food opportunities, polar bears lost the same amount of weight. "Some studies have suggested that polar bears could adapt to land-based foods to offset the missing calories during a shortened hunting period on the ice," said Nicholas Pilfold, Ph. D., lead author of the study and a postdoctoral associate in Applied Animal Ecology at San Diego Zoo Global. "Yet, our results contradict this, as unfed polar bears in our study lost mass at the same rate as free-ranging bears that had access to land-based food." Researchers also estimated starvation timelines for adult males and subadults, and found that subadults were more likely to starve before their adult counterparts. "Subadult polar bears have lower fat stores, and the added energy demands associated with growth," said Pilfold, "Future reductions to on-ice hunting opportunities due to sea ice loss will affect the younger polar bears first—especially given that these bears are less-experienced hunters." Today, it is estimated that there are approximately 26,000 polar bears throughout the Arctic. The Western Hudson Bay subpopulation of polar bears is currently stable, as the length of the ice-free season has shown recent short-term stability. However, past increases in the length of the ice-free season have caused declines in the number of bears, with subadults having a higher mortality rate than adults. The current research helps to shed light on the mechanisms of past population declines, as well as to provide an indication of what may occur if sea ice declines again. For nearly a decade, San Diego Zoo Global's researchers and its U.S. and Canadian partners have focused on developing conservation strategies to boost wild populations of polar bears. At the San Diego Zoo, polar bears "collaborated" with researchers at the U.S. Geological Survey in Alaska by wearing an accelerometer collar to track their movements. The data gained from accelerometers on collared polar bears—at the Zoo and in the Arctic— will provide scientists with new insights into the bears' daily behavior, movements and energy needs, and a better understanding of the effects of climate change on polar bears. Bringing species back from the brink of extinction is the goal of San Diego Zoo Global. As a leader in conservation, the work of San Diego Zoo Global includes on-site wildlife conservation efforts (representing both plants and animals) at the San Diego Zoo, San Diego Zoo Safari Park, and San Diego Zoo Institute for Conservation Research, as well as international field programs on six continents. The work of these entities is inspiring children through the San Diego Zoo Kids network, reaching out through the internet and in children's hospitals nationwide. The work of San Diego Zoo Global is made possible by the San Diego Zoo Global Wildlife Conservancy and is supported in part by the Foundation of San Diego Zoo Global. Explore further: Arctic conditions may become critical for polar bears by end of 21st century
News Article | November 25, 2015
Whalers fined An Australian court fined a Japanese company Aus$1 million (US$724,000) on 18 November and found the firm to be in contempt of court for killing minke whales in an area declared a sanctuary by Australia. According to the animal-protection organization Humane Society International (HSI), which, along with the Environmental Defender’s Office, brought the case against the firm Kyodo Senpaku Kaisha, this is one of the largest fines issued under Australian conservation law. The company caught whales in four different years, despite a 2008 injunction against the practice, says the HSI. Climate repeals The US Senate voted on 17 November to repeal a pair of regulations by the Environmental Protection Agency that would limit carbon emissions from new and existing power plants. Votes on both rules were led by Republicans and passed by a margin of 52–46; the House of Representatives is considering similar resolutions. Coming just two weeks before the United Nations climate summit in Paris, the resolutions are largely symbolic. US President Barack Obama promised to veto both repeals, and supporters do not have the two-thirds majority needed to override a veto. Tasmanian devils returned to the wild Tasmania has 39 more wild devils, after the latest batch of healthy individuals was released from the Devils Ark Santuary (pictured is manager Dean Reid) onto the Forestier Peninsula on 18 November. The area was cleared of Tasmanian devils (Sarcophilus harrisii) after an infectious cancer that is devastating populations of the endangered animals was detected there in 2004. A ‘devil-proof fence’ has now been installed to prevent the new, healthy population from mixing with animals afflicted with the deadly and infectious devil facial tumour disease. Statoil Arctic exit Norwegian energy company Statoil announced on 17 November that it would cease exploration for gas and oil in Alaska’s Chukchi Sea. The decision comes just over a month after Royal Dutch Shell suspended its own exploration off the Alaskan coast, citing regulatory uncertainty and a disappointing survey of the area’s fossil-fuel prospects. The Statoil decision sees the company exit early from 16 leases that were set to expire in 2020. L’Aquila verdict Italy’s highest court of appeal on 20 November upheld a decision to acquit 6 seismologists accused of manslaughter in regard to the 2009 L’Aquila earthquake, which killed more than 300 people. Prosecutors claimed that the scientists misled townspeople about the risk, leading them to stay in their homes instead of seeking safety. The scientists were originally given six-year prison sentences, but an appeals court in L’Aquila acquitted them last November, and reduced to two years the sentence of Bernardo De Bernardinis, former deputy director of the Italian Civil Protection Department, who was also convicted. De Bernardinis’s reduced sentence was upheld; he still faces a separate charge of manslaughter. Ebola setback In a setback to efforts to end the Ebola epidemic in West Africa, the World Health Organization announced three new cases of the disease in Liberia on 20 November. One of those individuals, a 15-year-old boy, died on 23 November. The country had been declared Ebola-free on 3 September. Sierra Leone was declared Ebola-free on 7 November, and the last case in Guinea was reported on 29 October, leading to hopes that the epidemic, which began in December 2013, might finally be nearing an end. Pandemic report A panel of physicians, scientists and policy experts has called for major reforms to the World Health Organization and other international health-response systems following the Ebola epidemic that has killed more than 11,000 people. The panel, convened by Harvard University in Cambridge, Massachusetts, and the London School of Hygiene and Tropical Medicine, released its report on 22 November (S. Moon et. al. Lancet http://doi.org/9gf; 2015). It also recommends measures to improve prevention, detection and response to outbreaks, and to speed research on diseases that cause them. See go.nature.com/jxxvs6 for more. Rare rhino dies Northern white rhinoceroses (Ceratotherium simum cottoni) are one step closer to extinction, after a 41-year-old female named Nola had to be put down after surgery at the San Diego Zoo Safari Park in California on 22 November. The last three remaining individuals — two females that cannot reproduce naturally and a male with a low sperm count — live at Ol Pejeta Conservancy in Kenya. Conservationists hope that the species can be saved through assisted reproduction techniques, using southern white rhinos (Ceratotherium simum simum) as surrogates. CRISPR cress The Swedish Board of Agriculture on 17 November told two Swedish universities that they do not need special approval for field trials of some cress (Arabidopsis, pictured) varieties mutated by the CRISPR–Cas9 gene-editing technique. In June, the European Commission had asked European Union member states to hold back on such rulings until it makes its own proposals on how to regulate organisms modified by new genetic techniques. But the Swedish authority said decisions needed to be made now, so that trials can be prepared for the next growing season. Chimps retired The US National Institutes of Health (NIH) is ceasing its chimpanzee-research programme altogether, two years after retiring most of its chimps. In a 16 November e-mail to the agency’s administrators, NIH director Francis Collins announced that the 50 NIH-owned animals that remain available for research will be sent to sanctuaries. The agency will also develop a plan to phase out NIH support for the remaining chimps that are supported, but not owned, by the NIH. See page 422 for more. Coal curbs The Organisation for Economic Co-operation and Development agreed on 18 November to restrict public financing for coal-fired power plants. Two years in the making, the agreement removes support for large, low-efficiency coal-fired plants while maintaining support for medium-sized, high-efficiency plants in countries facing energy shortages, and for small, less-efficient plants in the poorest countries. The restrictions will not apply to any coal-fired plants that are equipped to capture and store carbon emissions. UK research review A tensely awaited report into the future of the major UK research-funding agencies, released on 19 November, suggests the creation of a powerful umbrella organization called Research UK to manage the agencies. The review was led by Nobel-prizewinning geneticist Paul Nurse. Many scientists feared that it would recommend a total merger of the research councils, which collectively distribute some £3 billion (US$4.6 billion) of government research funding each year. Nurse recommends that Research UK be led by an experienced researcher, who would in effect be boss of the heads of the seven discipline-based councils. See go.nature.com/2rwzeu for more. Mega-merger Two major pharmaceutical firms are to merge in a US$160-billion deal, they announced on 23 November. Pfizer of New York will combine with Allergan, based in Dublin, in a merger that is expected to be completed by the end of 2016. The resulting firm will be named Pfizer but will be headquartered in Dublin — providing a significant tax break for the US firm — and will have more than 100 medicines in mid-to-late-stage development. The availability of antiretroviral drugs for HIV has increased women’s lifespans more than men’s in KwaZulu Natal in South Africa, concludes a study of more than 98,000 people (J. Bor et al. PLoS Med. 12, e1001905; 2015). Since free antiretroviral treatment became available in South Africa in 2004, declines in life expectancy have reversed for both genders. But progress is uneven, with women gaining more years of life than men. The authors recommend that HIV outreach activities be targeted to men. 30 November The leaders of the world’s nations gather to broker a climate deal at the United Nations’ Paris Climate Change Conference. nature.com/parisclimate 2 December The European Space Agency’s LISA Pathfinder satellite, which will hunt for gravitational waves, launches from Kourou, French Guiana. go.nature.com/rxrzuc
News Article | April 6, 2016
After a California condor pair's egg went mysteriously missing in the middle of the night, the duo is back on track, raising a foster chick that biologists surreptitiously slipped into the birds' mountain nest. The family affair began with condors #111, a 22-year-old female hatched at the San Diego Zoo Safari Park, and #509, a 7-year-old wild male. The two began courting in 2014, and nested together near the Hopper Mountain National Wildlife Refuge in southern California, according to the Cornell Lab of Ornithology. Before long, #111 laid an egg. A team of U.S. Fish and Wildlife Service (USFWS) biologists snuck into the nest on March 2 to set up a bird cam and check the egg's viability with a candle test, in which a bright light is used to check the growing fetus inside. They reported that everything looked good, and estimated that the egg would hatch between April 4 and April 6. [10 Species You Can Kiss Goodbye] But then, the egg went missing. On the night between March 20 and March 21, it disappeared. In order to save battery power, the bird cam does not record during the night, so there's no proof of what happened to the egg. But, in all likelihood, a predator made off with it, leaving only a few eggshell fragments behind, according to the Cornell Lab of Ornithology, which runs the cam. This development was worrisome to scientists, as the California condor (Gymnogyps californianus) is critically endangered, according to the International Union for Conservation of Nature (IUCN). In 2010, there were only 104 adult California condors of breeding age in the wild, and just 44 had produced surviving offspring, the IUCN said. After the egg vanished, USFWS biologists devised an action plan: On March 21, they rappelled into the nest and replaced the missing egg with a dummy egg. Condor #111 entered the nest cavity just as they left, and — to everyone's relief — began incubating the fake egg. Her partner, #509, incubated the dummy egg, too. In the meantime, the recovery team called the Los Angeles Zoo, which was raising eggs that condors had laid in captivity. The zoo gave one of its eggs to the USFWS scientists, who furtively rappelled into the nest again and swapped the dummy egg for the new foster egg on April 3. The swap worked. The adults — which look a bit like hunchbacked, black umbrellas — incubated the egg, and it hatched on April 4, making it the first time that a condor chick had hatched live on a bird cam, according to the Cornell Lab of Ornithology. It's unclear whether the 9-ounce (255 grams) chick is a male or female, but a blood test within its first year of life will clear that up. Once the chick turns 4 months old, biologists will tag it so that they can track it when it starts flying, at about 6 months of age. For now, both #111 and #509 are taking turns keeping the chick warm and feeding it. Bird enthusiasts can watch the chick grow up on the California condor bird cam, and follow it on Twitter: @CornellCondors. The biologists hope that the mystery thief responsible for the first egg's disappearance will leave the new chick alone. "Sometimes, condors select nest cavities that are accessible to terrestrial predators that are skilled climbers, such as bobcats, black bears and mountain lions," the Cornell Lab of Ornithology said. "We will continue to closely monitor the condor nestling via the live streaming camera and newly placed motion activated Bushnell game camera that is capable of taking nighttime images." Condor chicks remain dependent on their parents for more than a year, so birdwatchers will have plenty of time to watch the little chick grow up, the lab said. Copyright 2016 LiveScience, a Purch company. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.
News Article | September 14, 2016
The use of statistical methods to predetermine sample sizes was not necessary: in the main experiment, all healthy individuals of the world’s ‘Alalā population were tested, and all other experiments (as detailed below) likewise attempted to maximise sample sizes. Randomization procedures were used to establish the order in which subjects were observed in some experiments (as detailed below), and the order in which all video files were analysed; all videos for the assessment of inter-observer agreement were randomly selected. For some video analyses (as detailed below), scorers were hypothesis naive. ‘Alalā were studied in two captive breeding facilities operated by San Diego Zoo Global. With the species considered extinct in the wild11, 30, the world’s population consisted of 109 individuals (58 males; 51 females) in early 2013, with: 64 birds housed at the Keauhou Bird Conservation Center (KBCC), Hawai‘i Island; 44 birds at the Maui Bird Conservation Center (MBCC), Maui; and a single individual off-exhibit at San Diego Zoo Safari Park, California. The captive stock originated from a few founder individuals that had been collected from the wild since the 1970s, as described in detail elsewhere11, 29, 30, 31, 32. All birds available for testing in our study (referred to throughout by their studbook numbers) were of known ancestry, sex (determined through genetic analysis of blood samples33) and age, and had been reared in captivity (Fig. 2b). Male #67 had hatched from one of the last eggs laid by a wild pair, and three other subjects (#77, #78, #86) had temporarily lived in the wild (they had been released in the late 1990s, but were later returned to captivity30). Adult birds were kept as breeding pairs, or sometimes as singletons, and immature birds were housed in groups of up to eight individuals, to facilitate their socialization34. All aviaries at the two main facilities are multi-chambered, spacious outdoor enclosures (varying in size from ~3.0 × 6.0 × 3.7 m to 7.3 × 17.0 × 5.5 m), which are open to the elements, but have a roofed section for shelter. At the KBCC (purpose-built in 1996), the ground is covered in lava stones, with patches of live vegetation, while at the MBCC (repurposed building in use since 1986, with later extensions), some aviaries have concrete flooring. Standard fittings include a variety of branches and ropes for perching, a nesting platform, and a large water bath. All birds have access to cut vegetation (‘browse’) and sticks year-round, and pairs receive supplies of assorted nesting material during the breeding season. Enrichment protocols have changed over the years and varied slightly between facilities. Initially, all enrichment given to ‘Alalā was made of natural materials (for example, fresh browse, and logs of deadwood), but this was supplemented with artificial items (for example, food hidden inside dog toys, or wrapped in newspaper) from 2008 at the KBCC (and at the latest from 1999 onwards at the MBCC); a human-imprinted male (#35) was given artificial items as early as 2000. Food items were hidden in holes and crevices in wooden logs, or tossed into water baths, intermittently since at least 1997, and about once or twice a week since 2004, at the KBCC (since 1999 at the MBCC), and baited PVC tubes were presented from late 2012 onwards (since 2007 at MBCC). While this enrichment provided opportunities for tool use, in the vast majority of cases bait could also be obtained by bill alone, in contrast to the extraction tasks of our formal behavioural assay (see below). Importantly, to the best of our knowledge, the use of tools to extract hidden food was never demonstrated to birds at either facility. We conducted a species-wide assay of tool-use competence, using a standardized food-extraction task set (see below). Following pilot experiments with two subjects (female #94, and her son #134) in August 2012 and January 2013, we tested all healthy birds in both facilities between 23 January and 27 February 2013. With five birds excluded from experiments a priori for medical reasons, and one male tested later in the year (#67; tool use confirmed on 31 August 2013), our final sample comprised 104 subjects, which was over 95% of the world’s ‘Alalā population at the time (see Fig. 2b). As we effectively tested an entire species, it was not necessary to use inferential statistics to support findings. The experimental set-up consisted of (Extended Data Fig. 2a): a Koa Acacia koa log containing four drilled holes and two crevices, each baited with a quarter of a neonate mouse (or other preferred food in early trials at KBCC); 12 sticks of varying lengths as potential tools scattered in front of the log; and assorted native plant materials (KBCC), or two dead branched stems (MBCC; native materials not readily available), from which tools could be manufactured, wedged firmly into a wooden board to stand upright (for further details, see Extended Data Fig. 2a). The four different types of extraction task were designed to resemble foraging problems New Caledonian crows regularly solve with tools in the wild2, 4, 23. At both facilities, we used the same two near-identical logs to run trials in parallel. Encouraged by earlier anecdotal observations during routine enrichment sessions (Supplementary Video 4), we usually also placed a piece of mouse head in the aviary’s water bath, to see whether the subject(s) would fish it out with a stick; this complementary task proved useful, as it often attracted birds’ attention, and confirmed tool-use behaviour in one female (#95) that failed to engage with the main log set-up. Trials were scheduled to last for ~1.0–1.5 h, but were terminated earlier on a few occasions at the start of the study, while the test protocol was being established (n = 6 trials), or when all bait had been extracted (n = 24), cameras failed (n = 2) or due to experimenter error (n = 1). Food bowls were usually removed shortly before trials commenced, but birds sometimes found food scraps in their aviaries, and always had ad libitum access to water. An experimenter placed the fully-baited experimental log and the board with plant materials on the ground, before scattering the sticks underneath a large cotton sheet, out of view of the subject(s). Before the experimenter removed the sheet and left the aviary, several small food items were conspicuously placed on top of the log, to encourage approach and exploration of the set-up, and the water bath was baited (see above). At the KBCC, birds could be filmed with experimenter-operated video cameras through tinted or one-way-mirror observation windows, while at the MBCC, all trials had to be filmed with static video cameras hidden inside a rainproof box, placed ~1.5–3.0 m away from the experimental set-up. Subjects were temporarily isolated for individual testing (n = 83 birds), but we also ran some trials with pairs early on in the study (n = 3 birds) and some with larger groups where isolation was impossible owing to aviary layout (n = 18 birds). For logistical and ethical reasons, birds remained in visual contact with other ‘Alalā in adjacent chambers even when tested individually. Subjects that did not show tool-related behaviours in their first trial were re-tested for varying amounts of time (Fig. 2f). Immature ‘Alalā are usually housed in groups (see above); to examine experimentally how social context affects the expression of tool behaviour, we tested a sample of birds in their second and third year of life, both in their usual housing group and individually (Fig. 2e). Video footage from experimental trials was scored in randomized order by the same observer (B.C.K.) using Solomon Coder software35, and a subsample of 10 trials was re-scored by a second observer (S.S.) to estimate inter-observer agreement (Cohen’s κ for ‘extraction type’ [tool/bill/not-extracted] = 0.97, n = 70 cases; correlation coefficient r for ‘time spent probing with a tool’ = 0.99, P < 0.0001, n = 38 probing bouts); all analyses are based on the original data. Two main types of data were generated by our standardized behavioural assay. First, we used trials to establish whether or not birds used tools, irrespective of deployment context and extraction success (see Fig. 2b, f). Second, for those birds that did use tools, we examined aspects of tool handling, modification (and possible manufacture) and deployment, and quantified the speed with which they extracted bait from the log’s holes and crevices (see Fig. 2g; trials included only when birds had been tested individually). Formal species comparisons are pending, but when extracting meat from vertical holes, ‘Alalā’s performance (n = 52 birds that probed; 63% of attempted extractions successful; cumulative probing time until extraction (median, range): 26.8 s, 3.2–215.6 s; see top-left panel of Fig. 2g) is broadly comparable to that of New Caledonian crows (more difficult, deeper and narrower holes3: n = 15; 49%; 42.3 s, 5.8–161.6 s; unpublished data). Visual-field measurements require that subjects’ heads are held completely still for ~30–45 min9. While such temporary restraint is tolerated well by most birds, it cannot currently be used with ‘Alalā, given the species’ critical conservation status. As the width of the binocular field is determined to a large degree by lateral eye-movement amplitude (correlation, r = 0.82, P = 0.02, n = 7 Corvus spp.; data from table 1 in ref. 9), we opportunistically assessed, during behavioural trials and when handling subjects for routine health checks, how much birds can rotate their eyes forward during full convergence (see Extended Data Fig. 1b and Supplementary Video 5). To gain insights into possible genetic predispositions15, 16, 36, we studied the development of object-oriented behaviour in seven juvenile ‘Alalā that had been bred and puppet-reared37 at the KBCC in 2012 (hatch dates between 20 June and 16 July). Subjects were housed in two mixed-parentage groups (offspring of five different pairs) of three (Group A: subjects #206, #207, #208) and four birds (Group B: #200, #201, #204, #205), respectively. Following the facility’s standard procedures, birds were transferred from fledgling aviaries (~2.0 × 1.8 × 2.3 m) to large outdoor aviaries after they had acquired basic flight skills, at 61–69 days old. From 15 September onwards, the groups were housed in adjacent aviary chambers (each ~3.0 × 12.0 × 5.5 m), with visual contact through a wire-mesh partition, but they never saw adults during the full duration of our study. Furthermore, all staff were briefed never to use ‘tools’ (of any kind) in front of subjects, both during formal observation sessions and in all other contexts, including general husbandry activities (owing to an oversight, large metal tongs were used on a few occasions, to scrape old food from logs). As subjects were co-housed in groups, individuals that only expressed tool use later in the experiment could potentially have learned from those that used tools earlier (see Fig. 3c). This means that only the very first tool behaviour expressed in either of the two experimental groups was certain to be an independent ‘discovery’15, 19. We collected two main data sets. First, we employed a standard focal-bird observation protocol15, 16, 17 to document the natural development of object-oriented behaviour. Up to three days per week (usually on Tuesday, Thursday and Saturday), we conducted a morning (between ~6:30–11:00 h) and an afternoon (~12:00–16:00 h) session, aiming to collect ~5 min of video footage per subject (that is, 3 × 2 sessions × 5 min = 30 min, per subject per week). To avoid biases, the order in which groups were observed, and the order in which subjects were observed within sessions, was pseudo-randomized, and session start times were varied slightly within the above-mentioned time windows. Second, once per week (usually on Fridays), we conducted a ‘probe trial’ to assess subjects’ tool-use competence. We presented each group for ~15–20 min with a wooden platform, containing food-baited vertical holes and crevices (Extended Data Fig. 2b). The rationale of our study design was to monitor the development of the subjects’ tool-related behaviour (see Fig. 3c) with minimal environmental ‘scaffolding’; note that, in contrast, the New Caledonian crows raised in an earlier study had ad libitum access to extraction tasks15, 16. Platforms were initially baited with waxworms and cereal treats, but from 5 October 2012 onwards, we switched to mouse heads, neonate mice, and bright-red ‘Ōhelo Vaccinium reticulatum berries38. By January 2013, subjects in both groups showed keen interest in the hidden food, and often handled objects near the platform. For two reasons, however, their tool-use attempts largely failed: they sourced inappropriate materials as tools (for example, decaying pieces of fern), and even when suitable sticks were found, they struggled to extract food from tasks. We addressed these problems by providing sticks of assorted length (6 of 10–15 cm; 6 of 20–25 cm), loosely placed in the centre of the platform (sticks were never handled in view of the birds, and never pre-inserted into tasks), and by adding horizontal holes and crevices from which food was presumably easier to extract. These changes implemented, we concluded our experiment by providing birds with abundant opportunities to practice their tool-use skills (see entries ①–③ in Fig. 3c; trial length extended to ~30 min), with: a week of almost daily platform trials (23–29 January 2013; pooled data shown as ①); two re-test trials about a week later (4 and 6 February 2013; pooled data shown as ②); and another 1.5 weeks of exposure to the platform and a range of other extraction tasks without observation (8–18 February 2013), followed by a final platform trial on 20 February 2013 (entry ③). For reference, when protocols were altered on 23 January 2013, subjects were 151–181 days post fledging. Following standard protocols, subjects received near-daily aviary enrichment (sometimes immediately prior to observation sessions), including a variety of food items that required processing but were accessible by bill alone. The exception to this were baited opaque PVC tubes, which were presented on a single day in weeks 11, 12, 16, 19 and 24 (with week 1 commencing on 3 September 2012), to assess how birds’ tool-related performance on this task compared to that expressed during formal probe trials with the more demanding platform-mounted set-up (see above). These sessions were not included in focal-bird analyses shown in Fig. 3a, but some object insertions were documented slightly ahead of formal platform probe trials (Fig. 3c). Videos from all observation sessions were scored with JWatcher software39 in randomized order by two hypothesis-naive observers (S.W. and Caitlin Higgott), who achieved very high inter-observer agreement for a subsample of three sessions (correlation coefficients for handling rates for the object categories shown in Fig. 3a, r = 0.96–0.99, all P < 0.0001, n = 10 scores for each test); sessions for post-fledging weeks 3–5 (data from fledgling aviaries included) were scored with a particularly detailed scheme, with some behaviours coded as states, rather than as events, for time-budget analyses (weekly sample sizes were 3, 5 and 7 birds, respectively; Fig. 3d). We wrote code in R40 for extracting data from raw JWatcher output files, to calculate either object-handling rates (Fig. 3a; data for ‘sticks’ and ‘stones’ analysed with simple correlations) or time budgets (Fig. 3d; calculated for the time focal subjects were in view). Except for cross-species comparisons (see below), we plotted temporal data by calendar week (Fig. 3a, c), rather than by bird age or time since fledging, because the development of the younger birds in Group A may have been accelerated through observing the older members of Group B in the adjacent aviary chamber. In videos of probe trials, we scored which behavioural actions subjects performed near or on the platform, ranging from merely approaching the set-up to successfully using tools to extract bait (action types are numbered in the panels of Fig. 3c, and descriptions are provided in Extended Data Table 1). For cross-species comparisons, we extracted data on the development of object-oriented behaviour in New Caledonian crows and common ravens from figure 2 in ref. 17. For ‘stick’ manipulation, we only used data from untutored New Caledonian crows (2 subjects)17, and the object category ‘perch’ included all non-portable aviary fixtures. These species comparisons are for indicative purposes only (Fig. 3d), as the three studies considered varied in a range of factors, including details of subject housing, access to objects and extraction tasks, observation conditions and behavioural scoring (note considerable variation for ‘stick’ estimates for ‘Alalā), and the species in question are known to exhibit different rates of juvenile development4, 5, 8. Prior to the commencement of our study, ‘Alalā had regularly been observed using tools in both captive facilities. Staff did not consider these cases particularly noteworthy, as they were aware that the behaviour had been previously described for the congeneric New Caledonian crow. To provide context for our study, we collated information on these earlier, opportunistic observations, trying to locate written records12, 13 and conclusive photo or video evidence (Supplementary Video 4). It is worth noting that our sample of well-documented historical observations constitutes only a small fraction of the observations made by facility staff over the years. To examine the influence of environmental and/or social factors on tool-use competence, we reconstructed our subjects’ lifetime housing histories—that is, the time they had spent at different facilities, their allocation to particular aviaries and chambers, and their co-housing with other birds—using paper files and electronic spreadsheets held at the KBCC and MBCC. First, we conducted some basic checks, to see whether competence was related to being raised (first two years of life), or kept, in a particular facility (Fig. 2c). Next, we used our detailed housing data to investigate how well our study population was admixed socially, by simulating41 the flow of information—such as tool use—across birds42, 43. Using all dated housing entries in our database (n = 1,501 for 135 birds in 1996–2013), we first generated contact networks that specified which crow dyads were in potential visual contact at any given time, by sharing an aviary or occupying adjacent aviaries/chambers with a see-through wire-mesh partition (cumulative ‘co-housing matrix’ shown in Fig. 3e, left). As the expression of ‘Alalā tool behaviour is strongly age-dependent (Fig. 2d), and studies in other systems have shown that learning is often particularly effective during a ‘sensitive window’ early in life18, we considered only the subset of co-housing events in which one of the birds was adult (>2-years-old) and the other immature (<2-years-old). Our idealised simulation model assumed that, if the adult had the information at the time of co-housing, it was expressed and transmitted instantaneously to the immature. The information was never lost, so both the adult (and the immature, once old enough) could pass it on in subsequent co-housing events. We then traced (computationally) for all potential ‘innovators’ of information all possible transmission pathways through the time-ordered contact networks, identifying those reaching confirmed tool users by 2013 (grey dots in Fig. 3e, left, refer to immature recipients that were not among the confirmed tool users in 2013); the results are summarized in the ‘reachability matrix’ (Fig. 3e, right). From this matrix we computed44 the smallest number (m) of independent innovation events (rows) needed to ensure that every tool user (column) is reached. For the transmission dynamics described, m = 8. To establish a lower-bound estimate, we relaxed the transmission rules so that information could be passed between birds of all ages, yielding m = 1. Both simulations assumed highly conservatively that transmission was not only instantaneous but also deterministic (although we would expect considerable between-dyad variation in transmission probabilities due to differences in social-learning opportunities and phenotypic plasticity18, 45), but inevitably had to ignore possible pathways created by birds for which exact aviary information was unknown (16.3% of 1,501 housing entries). As explained in the main text, these analyses helped us to characterize the ‘social connectivity’ of our study population, but further behavioural experiments are required to demonstrate social learning in ‘Alalā. To examine phylogenetic relationships within the genus Corvus, we built a consensus tree (Fig. 1a) from sequence data that had previously been archived in GenBank by two independent studies6, 46 (note that C. macrorhynchos culminatus had erroneously been logged as C. culminatus in GenBank6). Where more than one sequence was available for a given species, we aligned them and produced a consensus sequence. We then aligned each region (CR, Gapdh, ND2, ND3, and ODC) separately using MAFFT47, and concatenated these alignments. For species that did not have coverage for a particular region, these regions were coded as Ns. We used this alignment to generate a consensus tree, using MrBayes48 (n = 10,000,000). Uncertainty about the specific status of some taxa affects the total number of species within the genus6, 8, 46 (for example, recent authors46 treated C. violaceus and C. minutus as distinct species, rather than as subspecies of, respectively, C. enca and C. palmarum8), but not the gross topology of the phylogenetic tree. Importantly, although more work is required to resolve the close relationships of C. moneduloides4, 6, 46, our analyses confirmed that the two tool-using species C. hawaiiensis and C. moneduloides are only very distantly related49. While our concatenation method enabled us to maximise data coverage, it complicated the estimation of divergence times; according to an earlier study, however, the last common ancestor would have lived in the mid-Miocene, ~11 million years ago (see figure 2 in ref. 46). The ‘Alalā is the only survivor of at least five species of crow that once inhabited the Hawaiian archipelago5, 26, 30. To assess variation in craniofacial features, we used previously published photos (figure 3 in ref. 26) of the fossil skulls of two extinct species (C. impluviatus, C. viriosus), and adapted (mandibles closed; flipped horizontally; re-coloured) and re-sized them for direct comparison with the portrait photo of a live ‘Alalā (adult female #94; Fig. 1f). The evolutionary history of this species assemblage remains unknown, but variation in bill morphology indicates well-differentiated foraging behaviour50, 51. The distribution of an undescribed species with “a bill modified for hammering”5 may be of particular relevance4 for understanding the evolutionary ecology of tool behaviour in ‘Alalā.
News Article | November 24, 2015
One of the four northern white rhinoceros left on Earth died yesterday (Nov. 22), leaving only three surviving members of the critically endangered species. Nola, a 41-year-old female rhino, lived at the San Diego Zoo Safari Park since 1989. In recent weeks, Nola suffered from a bacterial infection, and on Nov. 13, the aging animal underwent surgery to drain a large abscess in her pelvic region, which veterinarians finally identified as the source of her sickness. Though the procedure was successful in reducing the infection, Nola's condition grew worse, leaving her without an appetite and unable to move around, according to zoo officials. When intensified treatment efforts were unsuccessful, the animal's caretakers chose to euthanize her yesterday, in what was a "difficult decision," according to a statement released by the San Diego Zoo. [In Photos: The Last Surviving Northern White Rhinos] Nola follows in the footsteps of Nabiré, a 31-year-old female northern white rhino that died of a ruptured cyst in July at the Dv?r Králové Zoo in the Czech Republic. The deaths of these two critically endangered animals mean that just three northern white rhinos remain in the world. Habitat loss and poaching have kept the northern white rhinoceros (Ceratotherium simum cottoni) on the brink of extinction for years. The three remaining members of the species reside in captivity at Ol Pejeta Conservancy in Kenya, where they were transferred after living at a zoo in the Czech Republic. The four remaining northern white rhinos that roamed the wild of the Democratic Republic of Congo as recently as 2007 are now presumed dead, which means there are no known members of the species still living in the wild, according to the Ol Pejeta Conservancy. Of the three endangered rhinos that remain, two are female and one is male. But at 42 years old, the last northern white rhino male, named Sudan, is too old to mount a female, and his sperm quality is poor, researchers from the San Diego Zoo Institute for Conservation Research told Live Science in June. The remaining female members of the species, Najin and Fatu, are also unable to reproduce. Najin's age and health problems prevent her from mating, according to Ol Pejeta CEO Richard Vigne. And Fatu, who has never bred, has uterine problems that may prevent her from ever becoming pregnant. However, veterinarians are developing in vitro fertilization (IVF) methods that could one day be used to create northern white rhino embryos. Researchers are attempting to harvest eggs from the remaining female members of the species, as well as sperm from the remaining male. The embryos that may be produced using these sex cells could one day be carried by southern white rhinos, which are close relatives of the northern white rhinos. Copyright 2015 LiveScience, a Purch company. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.
News Article | November 22, 2015
The extinction of the northern white rhino (Ceratotherium simum cottoni) draws ever closer. Nola, a 41-year-old female that has lived at the San Diego Zoo Safari Park since 1989, was euthanized this morning after she stopped eating and her activity levels dropped. Nola had undergone surgery on Nov. 13 to drain an infected abscess within her pelvic region. The surgery was successful, but the zoo reports that Nola’s condition worsened over the past 24 hours. With Nola’s death, there are now only three northern white rhinos left on the planet, all of which live at Ol Pejeta Conservancy in Kenya. The two remaining female rhinos are incapable of natural reproduction. The last surviving male, Sudan, has a very low sperm count but the conservancy still has hopes for in vitro fertilization. San Diego Zoo recently set aside $2 million as part of an effort to keep the species from going extinct by implanting northern white rhino embryos into surrogates from the related southern white rhino subspecies (C. s. simum). That plan may still come to fruition, as the zoo has a collection of suitable genetic material in its Frozen Zoo. Northern white rhinos went extinct in the wild after years of extensive poaching for their valuable horns, which are used in traditional Asian medicine. The last wild northern white rhinos were killed in the Democratic Republic of the Congo in 2006. Nola is being eulogized today on Twitter under the hashtag #Nola4Ever.
News Article | November 22, 2015
Nola, an aging rhino that had resided at the California zoo park since 1989, had been receiving treatment for a bacterial infection, according to a statement on the zoo's website. She was placed under constant veterinary watch last week as her appetite and activity levels declined. After her condition worsened significantly, caretakers decided to euthanize her, zoo officials said. "Nola was an iconic animal, not only at the San Diego Zoo Safari Park, but worldwide," the zoo said. "Through the years, millions of people learned about Nola and the plight of rhinos in the wild through visits to the Safari Park, numerous media stories and social media posts." The three remaining northern white rhinos are at the Ol Pejeta Conservancy in Kenya, the zoo said on Facebook in response to an outpouring of comments from Nola's fans.
News Article | November 23, 2015
The last four northern white rhinos in the world are now down to three, as San Diego Zoo Safari Park loses Nola Sunday. The 41-year-old female northern white rhino, already geriatric, was euthanized by the safari park team after a week of listlessness and a massive pelvic abscess and bacterial infection. "In the past 24 hours Nola's condition had worsened significantly. Early this morning, the team made the difficult decision to euthanize her," read an official statement from the Safari Park. Nola’s death leaves the world with only three northern white rhinos, all protected 24/7 from poaching Ol Pejeta Conservancy in Kenya. In 1989, Sudan-born Nola arrived at the park in Southern California from a Czech zoo as part of a breeding initiative. The 4,000-pound rhino, the last of her kind held captive in the Western hemisphere, was considered an iconic and well-loved animal at the park and around the world. "Through the years, millions of people learned about Nola and the plight of rhinos in the wild through visits to the Safari Park, numerous media stories and social media posts," the zoo said of the dead rhino, which was endeared for her gentleness and affinity for back scratches from the zoo personnel. The news of Nola’s death came months after Angalifu, a 44-year-old northern white rhino, yielded to cancer at the same park. It also followed a couple of weeks after the transporting of six southern white rhinos — the northern whites’ close kin and with fewer than about 20,000 remaining in the wild — from South Africa to San Diego in an effort to save them from extinction. Poachers are estimated to kill about three from this breed every day. It is yet to be known if the southern and northern white rhinos are two separate species or are subspecies of one another. According to zoo spokesperson Christina Simmons, they will determine if the southern whites’ genes are similar enough to maternally surrogate embryos from northern white DNA. For some good news, a baby red panda was safely brought back to the Sequoia Park Zoo in the far northern coast of California after being lost four days earlier. The one-year-old panda was spotted walking about half a mile away from the zoo entrance until it was herded up a small tree by a concerned citizen, ready to be lured back to the zoo by staff.
News Article | November 23, 2015
Nola, a 41-year-old rhino brought to the Southern California park in 1989 as part of a breeding program, took a turn for the worse over the weekend following a Nov. 13 surgical procedure to drain a large pelvic abscess identified as the infection source, the zoo said in a statement. The 4,000-pound (1,800-kg) rhino had been placed under constant veterinary watch last week as her appetite and activity levels declined. After her condition deteriorated significantly, caretakers decided to euthanize the animal, zoo officials said. "Nola was an iconic animal, not only at the San Diego Zoo Safari Park, but worldwide," the zoo said. "Through the years, millions of people learned about Nola and the plight of rhinos in the wild through visits to the Safari Park, numerous media stories and social media posts." Her gentle disposition and affinity for having her back scratched made her a favorite of zoo staff. Northern white rhinos were declared extinct in the wild in 2008 because of poaching for their horns, prized on the black market for their supposed medicinal properties in some cultures. Nola was the only member of her kind left in captivity in the Western Hemisphere. With her death, just three others remain, all at the Ol Pejeta Conservancy in Kenya, zoo officials said. Nola was born in the wild in Sudan and captured at about 2 years of age, according to the San Diego Union-Tribune. She arrived in California from a Czech zoo. Her death came weeks after six southern white rhinos, close cousins of northern whites, were brought to San Diego from South Africa in an effort to bring Nola's kind back from the brink of extinction. Scientists remain unsure whether northern and southern white rhinos are two distinct species or subspecies of each other. Studies are under way to determine if southern whites, of which fewer than 20,000 are estimated to remain in the wild, are genetically similar enough to serve as maternal surrogates for implanted embryos that would be developed from northern white rhino DNA, zoo spokeswoman Christina Simmons said. Wildlife experts say southern white rhinos are in dire straits, too, killed by poachers at the rate of three a day.
News Article | November 23, 2015
"A northern white rhinoceros, one of just four left on Earth, died on Sunday at the San Diego Zoo Safari Park after suffering from a bacterial infection and age-related health issues, zoo officials said. Nola, a 41-year-old rhino brought to the Southern California park in 1989 as part of a breeding program, took a turn for the worse over the weekend following a Nov. 13 surgical procedure to drain a large pelvic abscess identified as the infection source, the zoo said in a statement. The 4,000-pound (1,800-kg) rhino had been placed under constant veterinary watch last week as her appetite and activity levels declined. After her condition deteriorated significantly, caretakers decided to euthanize the animal, zoo officials said."