Two cotton-top tamarins, similar to the one shown here, died of cold exposure last week at the Alexandria Zoo. The zoo employee who inadvertently left the monkeys in the cold has resigned. (Photo: Courtesy photo via Gannett) 
 
 People for the Ethical Treatment of Animals is calling for a federal investigation of the recent deaths of two cotton-headed tamarins due to cold exposure at the Alexandria Zoo. 
 
 The city of Alexandria, which operates the zoo, said the small monkeys' deaths remain under investigation. 
 
 Three tamarins at the zoo were inadvertently left out in the cold on Jan. 7, and two of them died "as a direct result of the caretaker's responsibility for the evening," a city news release said. Temperatures were in the 30s that night. 
 
 The person responsible for caring for the animals has resigned from zoo employment, city officials said. 
 
 "The incident is under investigation," Public Works Director David Gill said. "The employee, who was initially on administrative leave and had been removed from any animal care, has resigned. This appears to have happened as a result of human error and not a system problem." 
 
 Zoo Director Lee Ann Whitt called the incident "a tragedy." 
 
 PETA Foundation Deputy General Counsel Delcianna Winders said in an email: "These tamarins lived a sad life of deprivation in captivity, and their deaths were totally preventable. 
 
 "This fatal neglect is all too common in zoos and other places where animals are displayed for human amusement, and that's why PETA's motto reads, in part, that 'animals are not ours to use for entertainment.'" 
 
 PETA is asking the U.S. Department of Agriculture to investigate the incident for possible violations of the federal Animal Welfare Act. 
 
 "PETA wants enforcement to prevent any future act that could result in needless harm or deaths at the zoo," PETA's email said. 
 
 On Tuesday, PETA sent a letter to a USDA official to request an investigation of the "gross oversight" by the Alexandria Zoo regarding the deaths of the "two critically endangered cotton-top tamarins" and to ask that steps be taken to ensure the safety of the tamarin which survived the cold exposure as well as the safety of other animals at the zoo. 
 
 The letter was sent from Brittany Peet, deputy director of Captive Animal Law Enforcement for PETA Foundation, to Dr. Robert Gibbens, regional director for the USDA Animal and Plant Health Inspection Service, Animal Care, Western Region. 
 
 Regarding the circumstances of the tamarins' deaths, Peet wrote, "… Such gross oversight by the zoo points to the following likely violations of the Animal Welfare Act: 
 
 "9 C.F.R. § 2.131 (b)(1) ('Handling of all animals shall be done as expeditiously and carefully as possible in a manner that does not cause trauma, overheating, excessive cooling, behavioral stress, physical harm, or unnecessary discomfort.') 
 
 "9 C.F.R. § 3.85 ('Every person subject to the Animal Welfare regulations … maintaining nonhuman primates must have enough employees to carry out the level of husbandry practices and care required in this subpart. …') 
 
 "9 C.F.R. § 2.131(a) ('All licensees who maintain wild or exotic animals must demonstrate adequate experience and knowledge of the species they maintain.')" 
 
 Peet added: "Please also hold the zoo fully accountable for any and all violations that you discover during your investigation." 
 
 The cotton-top, or cotton-headed, tamarin is one of the world's smallest primates and is recognized by its fan of long, white hair on its head. The species is found in the tropical forests of northwest Colombia. 
 
 Read or Share this story: http://www.thetowntalk.com/story/news/local/2015/01/13/peta-seeks-probe-tamarins-deaths-alexandria-zoo/21708793/ ||||| Two small endangered monkeys died because a caretaker "overlooked" them and left them out in the cold at a zoo in central Louisiana, officials said. 
 
 The cotton-top tamarins, which weigh less than a pound, were left out in the cold last week at the Alexandria Zoological Park, city officials said. A third monkey survived the exposure. 
 
 The monkeys are among the smallest new-world monkeys. They're black and white, with a fan of white hair atop the head. They need temperatures of 76 to 85 degrees. The high last Wednesday in Alexandria was in the 50s while the overnight low was in the teens. 
 
 It's not clear exactly how the monkeys were overlooked or whether they had an outdoor "nest box" with a heating unit. City spokeswoman Cynthia Jardon wrote in an email Tuesday that she couldn't provide details because of an ongoing investigation. The caretaker resigned Monday, she said. 
 
 The monkeys are critically endangered, with about 1,800 in captivity and about 6,000 in a small area of northwest Colombia, according to the International Union for Conservation of Nature. 
 
 Public Works Director David Gill said in a news release "this appears to have happened as a result of human error and not a system problem." 
 
 Federal inspectors did not find any violations during the zoo's 2012 or 2011 inspections, the latest available in an online database. Rob Vernon, spokesman for the Association of Zoos and Aquariums, said the zoo is fully accredited. 
 
 Vernon said zoos are not required to report animal deaths immediately to either the USDA or the zoo association. He did not know whether the tamarins' deaths had been reported to AZA. 
 
 "They do often notify us right away when an animal dies. Then we oftentimes will ask for a report if something seems unusual," he said. 
 
 ___ 
 
 Online: 
 
 Zoo: www.thealexandriazoo.com/ 
 
 Cotton-topped tamarin care: http://www.csew.com/cottontop/enhusbandry/ench5.htm ||||| Thomas Marent / Visuals Unlimited/Corbis A mustached tamarin 
 
 Related Top 10 Evil Animals 
 
 For any species hoping to survive in the wild, the lifetime to-do list is agreeably brief: eat, mate, defend your turf and, above all, protect your young. It's that last one that seems the most primally encoded, and for good reason: it's hardly possible to pass on your genes if your babies die before they're old enough to have offspring of their own. And yet not only do animals sometimes fail to protect the young of their species  they often kill them themselves. 
 
 Infanticide is disturbingly common in nature. It's typically committed by males that take over a pride or pack and kill whatever babies are present to make room for the ones they plan to father. It's not nearly as common for parents to behave murderously toward their own babies, and it's much rarer still for a mother to be the attacker  especially among primates. Now a study in the journal Primates has revealed that in a species of monkey known as mustached tamarins, the mamas can be a deadly menace indeed  and their infanticidal tendencies can provide some insight into human behavior too. (See pictures of the primate species facing extinction.) 
 
 Mother tamarins do not have an easy job. Gestation is long  about 150 days  and they usually have twins, and those twins are usually big. It's up to the mother to carry that double load around until the babies are old enough to navigate the forest canopy themselves. The only thing that makes the work tolerable is that tamarin troops cooperate to rear young, but the conditions have to be right. There must be plenty of males to do the protecting and provisioning, and there can't be too many other females with babies of their own that also require attention. 
 
 An international team of researchers led by primatologist Laurence Culot of the University of Liège, in Belgium, ventured into the Amazonian lowlands of Peru to observe four troops of wild mustached tamarins to determine what distinguishes the babies that survive infancy from the ones that don't. The data they collected made those differences immediately clear. 
 
 When there were at least three assisting males in the troop, the researchers found, the survival rate for infants was an impressive 75%; when there were two or fewer males, the number fell to 42%. When a mother-to-be was the only gestating female in a group, the baby she gave birth to had an 80% chance of surviving at least three months. When there were two or more pregnancies, that forecast plunged to just 20%. "Births must be spaced by three months or more," the authors wrote, "in order to allow efficient helping behavior." (Watch a video about langurs being trained in India.) 
 
 Some of the deaths that resulted from bad spacing or inadequate helpers were accidental or from unknown causes. But in a number of cases the researchers observed, infanticide was to blame. And unlike mothers in the marmoset, meerkat and social-carnivore species who kill the competing females' offspring, the tamarins killed their own. In some cases, a baby would fall from a tree and receive only indifferent care when it hit the ground  which suggested that the mother either dropped it deliberately or wasn't much concerned when it fell accidentally. 
 
 In one especially gruesome case, the mother killed her baby with a bite to the head, then devoured its brain and part of its upper body  a quick protein hit that she then went to sleep off. At the time of the killing, there were fewer than three helper males in the group, and another female was just a month away from giving birth to her own babies. "Before that," the authors wrote, "the perpetrator had given birth to twins three times successfully when four or five adult or subadult males were present in the group." 
 
 The explanation for such pitiless behavior is as cold as it is unavoidable: tamarin mothers are simply very good at balancing their genetic ledgers and know when they're heading for a loss. If they're raising babies that have a poor chance of surviving anyway, why make a pointless investment of time, resources and calories trying to keep them alive? Better to cut their losses, bag the babies and wait for a better season to breed. (See the top 10 evil animals.) 
 
 Humans recoil at such stark genetic number crunching, but while infanticide among our species is socially and criminally proscribed, it does happen  and far too often. And when mothers are the perps, they are often facing some of the same kinds of pressures as the tamarins: uncertain resources (read: money) and an absent or unreliable male. The overwhelming share of mothers in such situations do nothing so heinous as killing their babies, but one provocative 1999 study argued that postpartum depression (PPD) is an adaptive strategy to achieve the same genetic culling by different means. 
 
 Anthropologist Edward Hagen of the University of California at Santa Barbara, who conducted the work, looked at all of the things his sample group of PPD mothers had in common and was able to rule out some of the obvious variables, such as unemployment or lack of education. Repeatedly, he found that the two things that correlated the most strongly were the health of the infant and the amount of child-care support the mother was getting. "Mothers with PPD mother less," Hagen wrote in his paper. Their depression informs them "that they have suffered a reproductive cost and that successfully motivates them to reduce that cost." (The heat Hagen took for a study that put so unsettling a spin on a psychological condition for which mothers themselves are not to blame discouraged him from pursuing the line of inquiry much further.) 
 
 Clearly, depressed or unsupported mothers have options tamarins don't, and in our species at least, nothing excuses willful neglect, never mind murder. But excusing something is not the same as explaining it. We may be the highest of the primates, but we remain members of that sometimes brutish club, and our lower cousins still do have plenty to teach us. 
 
 See the top 10 animal stories of 2010.
– There are about 7,800 cotton-top tamarins left on the planet, 1,800 of them in captivity—and two fewer of the species of tiny monkey the AP dubs "critically endangered" after a Louisiana zookeeper apparently forgot about them and left them to freeze to death. The one-pound tamarins, which originate in a pocket of Colombian tropics, like it hot—between 76 and 85 degrees—and temps at the Alexandria Zoological Park last Wednesday dipped down into the teens, killing two while a third survived. City officials say an investigation is ongoing, though "this appears to have happened as a result of human error and not a system problem." The zookeeper was initially put on administrative leave, but resigned Monday. Predictably unimpressed is PETA, which was never a fan of zoos to begin with and is calling for a federal investigation, reports the Alexandria Town Talk. Says deputy general counsel Delcianna Winders, "These tamarins lived a sad life of deprivation in captivity, and their deaths were totally preventable. This fatal neglect is all too common in zoos and other places where animals are displayed for human amusement, and that's why PETA's motto reads, in part, that 'animals are not ours to use for entertainment.'" In a letter bemoaning the zoo's "gross oversight," it's asking the USDA to look into violations of the Animal Welfare Act and "hold the zoo fully accountable. (Things turned out much better for a rhino who survived a poaching attempt and gave birth Tuesday.)