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Archive for January, 2011

Blue tit on feeder (thanks to Alan Weir)

Spring is on its way in the UK, despite grey and drizzly days that try to claim otherwise, and today I watched a group of blue tits (Cyanistes caeruleus) squabbling in the trees outside my office while I was on a call… a very welcome distraction. So this fortnight’s photo is of this charming bird, found in gardens and woodlands across the UK and Europe.

Interesting random fact: birds and insects can see ultraviolet light (which is invisible to humans), and many flowers that have avian or insect pollinators take advantage of this ‘extra’ vision by advertising the path to their nectar in this spectrum – it often looks like a glowing airplane landing strip!

Further Information

RSPB         
British Garden Birds       
People’s Trust for the Environment      
Elizabeth & Malcolm’s blue tit diary (with live webcam of a nest)       
Britsh Trust for Ornithology      
BBC Springwatch

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Giant panda (thanks to Marit & Toomas Hinnosaar) The giant panda (Ailuropoda melanoleuca) is one of conservation’s icons, but these bears are secretive and their ecological needs are not well understood. Scientists have long known that panda populations are strongly associated with bamboo (no surprise, as bamboo is the only food that giant pandas eat); however, new analysis of a large dataset of giant panda habitat-use has shown that they also prefer old-growth forest. In fact, after bamboo, old forest is their second strongest habitat association, and this preference is substantially stronger than their link with other factors previously deemed important for pandas, such as slope, canopy cover, and altitude.

Knowledge of an animal’s habitat requirements is vital to ensure that preserved areas, such as nature reserves, contain sufficient correct habitat to allow a sustainable population to survive. This research demonstrates that secondary forest (forest that has been felled and then allowed to grow back) is not equal to pristine forest when viewed by a panda, and that primary forest is essential to the continued conservation of the giant panda.

Reference

Zhang Z et al. 2011. Old-growth forest is what giant pandas really need. Biology Letters 10.1098/rsbl.2010.1081

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Killer whales (Orcinus orca), or ‘orcas’, are the largest member of the dolphin family. Like all whales and dolphins, orcas are mammals – they breathe air, and mothers produce milk for their live-born young.

Killer whale mother and calf (photo by Sam)Killer whales were originally thought to solely eat fish but, increasingly, research is demonstrating that killer whales in different populations specialise in different prey – and that these populations may even be distinct enough to be separate species.  For example, in the northeast Pacific, off the coast of the USA and Canada, three distinct populations have been observed: the resident population lives close to the shore year-round, feeding only on fish (usually salmon). A transient population moves in and out of the area – these feed on marine mammals such as seal lions and other whales. The third, offshore, population are less well-known but researchers have recently found evidence that they may be specialist shark eaters, preying on Pacific sleeper sharks. These populations act differently to each other, make different vocalisations, and do not interbreed. Similarly in Antarctica, populations specialise on fish, or seals, or minke whales, with some observed hunting penguins.

Killer whales have different strategies for each prey, probably learned from other members of their group (called a ‘pod’). Those hunting seals among the ice of Antarctica will coordinate their swimming into a rush towards an ice floe, creating a bow-wave that can knock a seal off the floe and into the water where it can be caught. 

Other seal hunting pods risk stranding themselves as they launch onto a seal colony’s beach in an attempt to grab an unwary seal close to the ocean edge.

Those populations that hunt other whales, however, will stop using echolocation, which could alert their prey to their presence, while they stalk their prey, and (once caught up to the prey) will harry mother and calf pairs to exhaust the calf, before separating the calf from the help of its mother and then swimming on top of the calf to drown it. 

Killer whales are extremely intelligent predators and their behavioural repertoire is intriguing; I look forward to marine biologists unveiling more of their lives.

References

Ford JKB et al. 2011. Shark predation and tooth wear in a population of northeastern Pacific killer whales. Aquatic Biology 11: 213-224

Morell V. 2011. Killer whales earn their name. Science 331: 274-276

Morin PA et al. 2010. Complete mitochondrial genome phylogeographic analysis of killer whales (Orcinus orca) indicates multiple species. Genome Research 20: 908-916

Further Information

MarineBio

Smithsonian Ocean Portal

Convention on Migratory Species

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