Bigger Gorillas Better at Attracting Mates and Raising Young
ScienceDaily (May 1, 2012) — Beauty may be in the eye of the beholder, but even for gorillas, some traits stand out. A new study conducted in the rainforests of the Republic or Congo shows that female western lowland gorillas seek out bigger mates to father their offspring.
(via fyeahgreatapes)
A couple of photos from a fertility check on Dana the orangutan this evening. Late finish at work but definitely worth it. Amazing to get so close to a critically endangered animal, such as this. But also a bit sad to see such a powerful animal reduced to such a state. We had to dart her to put her under and transport her to the surgery. Once there we had a human gynecologist and anaesthetist in to do the procedure. They were pretty excited about it all. The good news is that although she had a still birth previously, after which she was shown to have blocked fallopian tubes, the blockage has now cleared. This means she should be staying at Durrell to try and breed from again. Had she remained infertile she would have been moved to a non-breeding group in France, which would have been a real shame as she has real character and is even know for her skills as an artist! She loves painting and her work fetches a tidy bit of money for the charity :O
(Source: headisananimal, via fyeahgreatapes)
While it may not be as socially acceptable among humans, a female choosing to take multiple mates is a common phenomenon in the animal kingdom. But why the practice of polyandry (a female having more than one male mate at a time) is so prominent is still a mystery in most species.
Most theories predict that taking multiple mates would be risky for a female without adding benefits. However, new research finds that in gray mouse lemurs, a type of small primate from Madagascar, healthy females seek out multiple mates in the few hours of one night they are receptive to mating every year. These multiple mates must confer some kind of benefit to the females, though exactly how they benefit is unknown.
“Males get benefits from mating with multiple females, because they can impregnate multiple partners,” study researcher Elise Huchard, of the German Primate Center in Göttingen, told LiveScience. “In most species, females only have a few oocytes [eggs], so mating with multiple males will not increase the number of offspring they will have.”
During the intense few hours female lemurs mate annually, two things can happen — either different males chase one female up to 100 times an hour, with some chases ending successfully in mating, or one male monopolizes her the whole night.
The females have a choice to make: Either let these males exhaust them while hunting for food, or choose to hide from the males and miss a night of feeding. During their normal breeding season, females are typically smaller than males. To see if size guided the choice and larger females could fight off the males better, the researchers fed the females either a normal food or a reduced-calorie chow.
They then watched the females on their mating nights, in a cage with three male lemurs. They expected to see the larger females push off the unwanted, harassing suitors. Instead, the researchers saw the heavy females scurrying around their cages mating with multiple males. The skinny females were more likely to be monopolized by one male lemur, and had fewer mates overall.
“Polyandry might not respond only to sexual conflicts [harassment], but also provide benefits to females,” Huchard said. “That’s probably quite general in animal societies; it’s been found in multiple studies in invertebrates.”
There is some evidence that a type of cryptic choice between different sperm donors occurs in these gray mouse lemurs. Previous studies have found that female lemurs in the wild preferentially use the sperm from mates with certain genes that are different from hers. Researchers don’t know how, but after mating with multiple males, the females are able to choose which male fathers her baby lemurs. It’s possible she can distinguish between each mate’s sperm, and uses only that from the most compatible mates. In other species, it seems a female’s ability to make a cryptic choice can offer benefits to her offspringl. The female can choose males that are better genetic matches, for example those that aren’t her close relatives, which would make for healthier offspring. And so this cryptic choice in mouse lemurs could be one way that taking multiple mates can benefit females in the long run, allowing them to choose the best genetic match, the researchers said. The study was published Tuesday (Oct. 4) in the journal Proceedings of the Royal Society B: Biological Sciences. From LiveScience
By now, I know of few people who haven’t seen the movie, Mean Girls. But in case you haven’t, here’s what you should know about it: the story is essentially an explanation of social cliques and aggressive teenage girl behavior. As a study recently published in Behavioral Ecology suggests, this agonistic behavior between females in cliques is not exclusive to human primates, but is found in our non-human primate kin as well. Over 18 months and 1027 interactions, Huchard and Cowlishaw (2011) discovered a correlation between sexually receptive female baboons and female-female aggression in groups. In female baboons, sexual receptiveness is typically a period in which individuals are estrous, or “in heat.” A way in which a female can display this information is through sexual swellings, or a swelling of the perineal skin, which indicates ovulation. Additionally, females with wider sexual swellings are perceived as “sexy,” as they attained sexual maturity earlier and generally have more offspring that survive (Domb and Pagel 2001). With that in mind, enter female-female competition. Female-female competition is thought to occur more often under circumstances where resources for success in reproductive factors might be limited: for example, yielded access to food resources inhibits successful gestation or production of milk or helpful mates that provide more access to resources through social rank. In the study performed by Huchard and Cowlishaw, sexual receptiveness was perceived to be the driver of aggressive behaviors as sexually receptive females received the most aggression, while lactating mothers received the least. It is thought this might be a tactic to delay conception; thus, females who have already conceived or have offspring would be more likely to receive access to resources and thereof prevents competition. Females who eat less (or would have limited access to food resources) also tend to have less reproductive success (Altmann and Alberts 2003). In addition, it is also possible by inflicting the cost of aggression onto sexually receptive females, the stress may make it more difficult to conceive or support a pregnancy (Beehner et al. 2006). Therefore, by being aggressive to these sexually receptive females, pregnant females or females who have offspring are conserving their resources and limiting the competition. While no reports of any baboons getting thrown in front of buses have been reported yet, if it does happen—be sure to check the sexual swelling for the baboon version of Regina George.
A Scottish zoo is planning to start a new breeding programme for chimpanzees, in the wake of recent research suggesting that captivity drives chimps mad. The plan for new chimpanzee breeding at Blair Drummond Safari Park near Stirling follows findings from the University of Kent showing that serious behavioural abnormalities – “some of which could be compared to mental illness in humans” – are endemic among captive chimpanzees. The research, focusing on 40 chimps in six leading but unnamed zoos in the UK and the US, found that all the animals studied engaged in abnormal behaviour, which included self-mutilation, repetitive rocking, the eating of faeces and drinking of urine. The chimps came from many different backgrounds, and the researchers were unable to isolate any single cause, other than the one thing they all had in common – that they were in captivity. “We suggest that captivity itself may be fundamental as a causal factor in the presence of persistent, low-level, abnormal behaviour – and potentially more extreme levels in some individuals,” said the leader of the study, Nicholas Newton-Fisher, an expert in wild chimpanzee behaviour. But the findings, published in the online science journal PLoS ONE, are not deterring the Blair Drummond Safari Park, which already has chimpanzees Chippy and his half-sister Rosie, born there 23 years ago, and wishes to bring in a new female in the hope that she and Chippy will mate. “I do not believe that captivity is inherently bad for chimpanzees,” said head keeper Alasdair Gillies. “There may be individuals in captivity who do display abnormal behaviour, but I think that is likely to be a result of their background. These abnormal behaviours could be learned culturally – chimps often imitate other chimps.” Mr Gillies added: “We will be pressing ahead with our breeding programme.” The Blair Drummond chimps live on a large wooded island on a lake at the park. The park believes they are of the subspecies Pan troglodytes verus, the western chimpanzee, and DNA tests are being carried out to establish this. “They are quite rare, with not many in zoos in Europe,” said the park manager, Gary Gilmour. “If it turns out that they are western chimpanzees, it would be very important from a conservation and breeding point of view. With around 30,000 left in the wild, and with deforestation in their habitat, and chimps being killed for bush meat and also taken for the pet trade, numbers are still decreasing, so we have to have stable groups in captivity for the future.”
Read More at The Independent
Howletts Animal Park near Canterbury in England is home to three Gelada Baboons – one male, named Agolo, and two females named Jima and Sereba. Keepers were thrilled when they discovered that Sereba had been successfully mated by Agolo resulting in the birth of a male baby named Leena. Agolo and Sereba have proved themselves to be very successful parents while Jima has taken on the role of Aunt to help out hardworking Mum and Dad.
Primate Keeper Jamie Wharton said: “It’s great watching Leena investigate his open-top enclosure and graze with his parents. As he gets older he will develop an impressive mane like his father.” As the male Gelada develop they grow a mantle (a mane of hair) that surrounds their head and neck. Neil Spooner, Animal Director, said “These baboons are quite unique in that they are the last surviving species of grass grazing primates. To have a successful birth is great news for the future.” 
Source ZooBorns
Photo Credit: Dave Rolfe
