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Since its doors first opened in 1910, the National Museum of Natural History has inspired curiosity and learning about the natural world and our place in it. Building upon the strong foundation of our extensive collections, the staff of the museum have been at the forefront of essential scientific exploration and research, and groundbreaking public exhibition and education. This slideshow and the website (www.mnh.si.edu/onehundredyears/) is a living documentary of the Museum’s 100-year history.

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Images: Lesser bulldog bats from Panama that were used in this study. (Photos courtesy Silke Voigt-Heucke)

To test the idea that echolocation calls can communicate social information for bats, the scientists recorded the ultrasonic echolocation calls emitted by lesser bulldog bats (Noctilio albiventris) and bats of other species, and then played them back to bulldog bats held in temporary captivity. They observed that captive bats reacted differently to calls made by bats of their same species than they did to calls by bats of another species. They also observed the bats respond differently to calls from bats which shared their roosts and to the calls of unfamiliar bats. The experiments were conducted in Panama. Ultrasonic white noise was used as a control in the experiment.

This video shows a lesser bulldog bat in a holding container responding to the ultrasonic calls of one of its roost mates. The audible chirps heard in this video is the bat’s non-ultrasonic voice. (Video courtesy Silke Voigt-Heucke)

“We were able to show that bats respond with a set of social behaviors [crawling, nodding, wing stretching, etc.] to the playback of echolocation calls,” the scientists write in a recent article in the journal “Animal Behaviour.” They conclude that N. albiventris can indeed distinguish between the ultrasonic calls of bats of their same species and bats of a different species, and between the calls of familiar and unfamiliar bats.

Our results demonstrate that echolocation calls are not only “perceived and processed by the individual producing the sound,” the scientists write, but that “other individuals may obtain information about species identity and group affiliation by listening to echolocation calls.” Authors of the paper are Silke L. Voigt-Heucke of the Leibniz Institute for Zoo and Wildlife Research; Michael Taborsky of the University of Bern, Switzerland, and Dina K.N. Denchmann, a research associate at the Smithsonian Tropical Research Institute in Panama.

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Image left: Prehistoric megafauna, painting by Jay Matternes.

New world megafauna such as mammoths, bison and camelids that were alive at the end of the Pleistocene epoch (some 13,000 years ago) would have produced massive amounts of methane-rich flatulence and belching, thanks to the cellulose-digesting microbes in their guts. Human hunting activities likely made a sizable dent–anywhere from 12.5 to 100  percent–in the level of atmospheric methane at that time. As a result, a cooling in transregional temperatures of the Younger Dryas period may be attributable in part to the rapid eradication of some 100 herbivorous species.

“The timing of the extinction aligns perfectly with the arrival of humans in the Americas,” Lyons says, “and their hunting may have contributed to this famous cool-down.” A drop of 9 to 12 degrees Celsius is believed to have occurred within the Younger Dryas stadial, or the “Big Freeze,” which came between the Pleistocene and Holocene epochs.

Chart right: The extinction of megafauna (indicated by red shaded region) closely coincides with an abrupt drop in atmospheric methane concentration at the onset of the Younger Dryas (indicated by blue shaded region). Time is given in kiloannum. Scientists estimate that prior to the extinction event, large-bodied herbivores in the Americas released about 9.6 Tg of methane to the atmosphere annually. The loss of these species could be responsible for 12.5 to 100% of the overall methane decline. Atmospheric methane concentrations during the past 15,000 years are derived from the Greenland ice core samples.

Ice core samples and fossil and archaeological records, combined with body mass and gut size calculations of these ancient animals, informed the methane estimates derived by the authors.

The research team, which was led by Felisa A. Smith of the University of New Mexico, and assisted by Scott M. Elliott of Los Alamos National Laboratory and Lyons, also found the Intergovernmental Panel on Climate Change is likely undervaluing the amount of methane emitted by non-domesticated animals.

As a result of their findings, the authors propose that the beginning of the ‘Anthropocene’ be recalibrated to 13,400 years ago instead of 8,000 years ago when ancient farmers are known to have cleared forests to grow crops. –Brian Ireley

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Photo left: A howler monkey eating Astrocaryum fruit. 
(Photo by Greg Willis)

Long before dawn on March 19 and 20, Katie Milton and a group of stalwart volunteers, each armed with flashlight and compass, spread out into the jungle to take up positions at 35 listening stations marked on their maps of the island. 

Just before sunrise, howler monkeys launch into a chorus of howls, roars and barks.  From 5:15 a.s. until 6:30 a.m., each volunteer recorded the time and direction of these vocalizations and estimated the distance to each group that they could hear from their stations.  As they walked back to the lab in the early morning light they noted locations of all monkey groups they saw.

“It amazes me that volunteers want to get up at 4 a.m. to walk through the dark forest alone for an hour or more. But it is a thrill when they hear that first howl and know the dawn chorus is beginning,” Milton says.

Photo right: Students from the University of Panama attend a pre-census workshop.

Lines drawn on a map from each station toward the compass angle of the observed sounds intersect, marking the estimated location of each group.  Based on this technique called triangulation Milton estimated that there are 60-70 groups on the island.  By multiplying the number of groups by the average number of individuals in a group—between 17 and 18 monkeys— she concluded that there are roughly 1200 individuals in fairly evenly spaced groups.     

Census volunteers always include internationally known ecologists: Smithsonian staff scientists and visiting scientists, as well as current students and fellows.  Barro Colorado’s game wardens and two Panamanian national forest police manned some of the most inaccessible listening stations. Eight highly-motivated students from the University of Panama arrived on the Island on March 18th to participate in a 2-day workshop on determining primate densities that included volunteering for the count.

Photo left: A baby howler monkey with a bot fly lesion on its neck. An ongoing study of the cause of death of howler monkeys on Barro Colorado has identified the howler monkey bot fly, Cuterebra baeri, as the single most important factor.

Milton organized the first island-wide group count 33-years ago in March, 1977. That census also revealed approximately 65 groups and thus, around 1200 monkeys.

“It doesn’t look like howlers on Barro Colorado have suffered from any devastating diseases or other catastrophic problems for the last three decades,” Milton says. “Groups are larger at some times of year and smaller at others, which seems to reflect births and the specific causes of death that affect different ages of monkeys at different times of the year.”–Beth King

To listen to audio Files of howler monkeys and interview with Katie Milton, visit this Web site:
http://biogeodb.stri.si.edu/bioinformatics/dfm/metas/search/stxt:howler/type:Audio

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Following a final ultrasound and hormone analysis, staff at the Smithsonian’s National Zoo confirmed late yesterday (Tuesday, April 27) that female giant panda Mei Xiang (may-SHONG) is not pregnant but was experiencing a pseudo, or false, pregnancy during the past several months.

Image right: National Zoo staff perform an ultrasound examination on giant panda Mei Xiang.

National Zoo scientists, veterinarians, keepers and volunteers from the Friends of the National Zoo were keeping a close eye on Mei Xiang, monitoring her hormone levels and behavior, as well as conducting weekly ultrasound exams in an attempt to determine if she was pregnant. On April 22, Mei Xiang’s progestagen concentrations had declined sufficiently to start the 24-hour watch. On reaching normal baseline levels, this decline ends in either the birth of a cub or the end of a pseudopregnancy. Based on current hormone analyses, and not having seen a fetus during the ultrasound exams, Zoo researchers have determined that Mei Xiang experienced a pseudopregnancy.

Image left: Mei Xiang (Meghan Murphy photos)

Female giant pandas almost always undergo a pseudopregnancy when they ovulate but fail to conceive. During a pseudopregnancy, hormonal changes and behaviors are identical to those of a true pregnancy, making it very difficult to determine if a giant panda is actually pregnant or not. This is the fifth time Mei Xiang has had a pseudopregnancy. Giant pandas ovulate only once a year. Mei Xiang gave birth in 2005 to Tai Shan, who was sent to Wolong’s Beifengxia Base in Ya’an, Sichuan, China, in February to join its breeding program.

National Zoo staff expect Mei Xiang to return to normal, hormonally and behaviorally, in the coming days, which includes an increase in appetite and activity level. The Fujifilm Giant Panda Habitat will reopen today at 10 a.m. It had been closed to provide Mei Xiang with a quiet environment in the event that she did give birth.

Giant pandas are endangered; scientists estimate there are around 1,600 remaining in the wild.

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This photo of an ocelot was taken by Smithsonian scientists during a recent camera-trap survey of these animals in the Peruvian Amazon.

[...more]

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“Because lions naturally live in social groups, introducing our lions into a common territory provides social enrichment,” said Rebecca Stites, a lion and tiger keeper at the National Zoo. “Providing appropriate and varied enrichment opportunities for our animals, including social enrichment, is just as important as ensuring that our animals have good medical care and proper nutrition.”

Image right: Male lion, Luke, spent more than a year interacting with females, Naba and Shera, through a mesh door before meeting them face-to-face. (Photo by Mehgan Murphy).

 Although the National Zoo has managed lions in the past, it has been many years since it had the right combination of animals by age and gender to develop a pride. But doing so takes more than merely putting the Zoo’s current three African lions, Luke, Nababiep and Shera, together and hoping they get along and breed—it is a process that requires extensive planning, knowledge of the species’ natural history and an understanding of the individual animals involved. 

“Animal keepers spend a considerable amount of time observing the behavior of individuals and getting to know their temperaments,” said Craig Saffoe, acting curator of lions and tigers. “Even though lions are a social species, introducing individuals who are not familiar with each other can be highly dangerous. Any of these animals can hurt or kill the other if we don’t do our job well.”

The research and patience has paid off. The sisters, Nababiep and Shera, have spent short periods of time with the male, Luke, individually and simultaneously. This happened only after they each had spent more than a year sniffing Luke through a mesh door (called a “howdy door”), and keepers observed their reactions to determine how they might respond face-to-face. If they continue to get along indoors, they will be brought together in an outdoor enclosure later this spring. The keepers will continue to watch the animals carefully throughout the process and if they determine that the safety of the animals is at risk at any point, this process may take longer.

Image left: Sisters Naba and Shera have, so far, been successfully introduced to male, Luke, as part of the National Zoo’s attempt to build a lion pride. (Photo by Jessie Cohen).

 As part of these introductions, 4-year-old Luke and 6-year-old Naba have bred, though the Zoo will not be able to determine whether she is pregnant until the beginning of April. If Naba does not go into heat by then, keepers can presume she is pregnant and not experiencing a pseudo-pregnancy. Although 5-year-old Shera has not mated with Luke, the Zoo ultimately hopes that both females give birth to two to four cubs (the typical number in a litter), resulting in a pride of up to 11 lions.

The Zoo’s cat experts reached out to about a dozen other institutions to learn how they built their prides, and it will conduct its own research in the coming months to contribute to the North American Species Survival Program for African lions. Volunteers will help keepers observe how the lions spend their time, how close they stay to one another and what times of the day they engage in social play. They will also watch the lions’ breeding and territorial marking behaviors.

“These three lions were brought to the National Zoo specifically for the purpose of breeding and introducing new genes into the existing U.S. captive population,” said Kristen Clark, a lion and tiger keeper. “The public will have the unique opportunity to observe the social interactions of a real lion pride, learn how charismatic and crucial this species is and hopefully be engaged enough to support conserving this species in the wild for future generations.”

In the wild, a typical male becomes the resident male in a pride, which consists of related females and offspring, at the age of 4. Although females in a pride do more than 80 percent of the hunting, the social structure of a pride is more complex than researchers once thought. For example, in smaller prides, males may be more active in hunting. The formation of prides makes lions unique among the great cats, many of which are solitary animals. Hunting, disease and habitat loss have contributed to a decline in the population of African lions, which are considered a vulnerable species by the International Union for Conservation of Nature and Natural Resources.

To follow the National Zoo’s progress in building a lion pride, read the updates from the Zoo’s lion keepers. You can also check for updates on our Twitter feed and Facebook page.

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