Sticks and tricks: Bowerbirds use interior design and optical illusions to attract females

Human men aren’t the only ones to show off for the ladies.  In fact, their stabs at romance seem a bit shabby when compared to the courtship displays bowerbirds put on for females they are trying to charm.

Imagine if a man built you an entire house and put all of your favorite things in it to get you on his good side?  A male bowerbird does just that, building a shelter or “bower” of sticks and elaborately decorating it with anything he can find to impress the female in question:

Bowerbird 1

Bower of a Vogelkop bowerbird (Amblyornis inornata) decorated with natural and man-made objects

But that’s not all – it turns out that bowerbirds are very particular about the type and arrangement of objects they place in and around their bowers.  Apparently, female satin bowerbirds prefer the color blue, which is perhaps why they have evolved such strikingly blue eyes (see picture below) so the males seek out blue objects over those of other colors.

Satin_bowerbird

Satin bowerbird (Ptilonorhynchus violaceus)

Furthermore, male bowerbirds construct their bowers to create an optical illusion.  Objects are not randomly placed around their court, but instead placed in a size gradient with smaller objects closer to the entrance of the bachelor pad and larger objects farther away.  This optical illusion is called forced perspective, and causes all of the objects to look the same size while the entrance of the bower appears smaller than it actually is.

bowernest

Satin bowerbird with female

12713-satin_bowerbird-cswHow does this help the male bowerbird snag a female?  If the bower entrance looks smaller than it is, then the male hopping and dancing around the bower entrance in his courtship display will appear larger than he actually is!  Males are very specific about constructing this optical illusion and will in fact recreate it in three days if it is disturbed.

Perhaps we humans should take a leaf out of the bowerbird’s book – I’m sure the ladies wouldn’t complain!

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References:

“Bowerbird.”  Wikipedia.org.  http://en.wikipedia.org/wiki/Bowerbird

Photographs from Arkive site:  http://www.arkive.org/vogelkop-bowerbird/amblyornis-inornata/image-G66592.html.

Bowerbird optical illusions:  http://www.livescience.com/18015-bowerbird-mating-illusion.html.

Animal romance National Geographic page: http://newswatch.nationalgeographic.com/2013/02/14/wild-romance-weird-animal-courtship-and-mating-rituals/

Bowerbird informational video from National Geographic:  http://ngm.nationalgeographic.com/video/player#/?titleID=bowerbirds&catID=1

Bowerbird information from National Geographic:  http://ngm.nationalgeographic.com/2010/07/bowerbirds/morell-text

Bowerbird stealing man-made objects video from National Geographic:  http://video.nationalgeographic.com/video/animals/birds-animals/ground-birds/weirdest-bowerbird/

Satin bowerbird picture from Wikimedia commons is under a Creative Commons license.

Arkive photographs taken by:

© Tim Laman / naturepl.com

Nature Picture Library
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Tel: +44 (0) 117 911 4675
Fax: +44 (0) 117 911 4699
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Arkive pictures may be reproduced for educational, scientific, or conservation purposes.

From Marlin to Marilyn: Clownfish Change Their Genders! Bizarre Courtship and Mating Rituals in the Animal Kingdom

Clown_fish_in_the_Andaman_Coral_Reef

Clownfish in anemone home

It turns out Finding Nemo had it wrong.  When a barracuda ate mom in the first scene of the movie, Marlin would not become a single dad, because being a single dad clownfish is impossible.  Realistically, Marlin would have become Marilyn– a single mom!

Clownfish are protandrous sequential hermaphrodites.  In other more pronounceable words, clownfish start their lives as males and then change into females.  Why is this necessary?

Clownfish2

Clownfish live in sea anemones and have adapted so they are unharmed by the anemone’s stings.  Because of its unique mutualistic relationship with the anemone (the clownfish eat parasites off the anemone, effectively cleaning it), the clownfish is reluctant to wander too far beyond its tentacly home.  This becomes problematic when the clownfish wants to meet members of the opposite sex, so the clownfish has evolved an interesting mechanism – sequential hermaphroditism – to overcome this obstacle.

Nemo

Marlin and Dory from Finding Nemo movie

Instead of braving the dangerous open waters beyond the reef (no, neither Marlin nor Nemo would realistically breach the “drop-off” and make it back alive), all the clownfish living in one place are males except the oldest, which is always a female.  After the head female dies, the next-oldest male turns into a female!

I suppose Pixar would’ve had a hard time explaining why they turned Marlin into Marilyn after one scene – I would’ve been confused too.  But in reality, the animal world of romance hosts a plethora of bizarre courtship behaviors, mating rituals, and other such oddities that put human courtship to shame!

References:

Clownfish picture 1 by ecatoncheires on Flickr: http://www.flickr.com/photos/ecatoncheires/2335044473/.

Nemo picture: from Cthomasuscg on Flickr:  http://www.flickr.com/photos/cthomasuscg/3304908183/

Interesting animal romance behaviors:  http://www.care2.com/greenliving/animal-romance-they-have-sex-how.html?page=1.

“Sequential hermaphroditism.”  Wikipedia.org:  http://en.wikipedia.org/wiki/Sequential_hermaphroditism

Clownfish information at Shedd Aquarium:  http://sea.sheddaquarium.org/sea/fact_sheets.asp?id=72

Clownfish information at Visit Sea Life:  http://www.visitsealife.com/explore-our-creatures/clownfish.aspx

Clownfish information at Evolution Faq:  http://www.evolutionfaq.com/articles/sex-change-nature-coral-reef-fish

Lions, tigers, and bears, oh my! What is a keystone species and how can conservationists use them?

Lion (Panthera leo)

tiger cub

Tiger (Panthera tigris)

Grizzly bear (Ursus arctos horribilis)

Grizzly bear (Ursus arctos horribilis)

What do these three animals have in common?  No, it’s not that they’re all featured in a popular film.  It’s not even that they’re all at the top of the food chain, although that’s closer.  Lions, tigers, and bears are all keystone species.

In architecture, the keystone at the top of an arch holds the arch together.  Without the keystone, the whole arch and building surrounding it will collapse.  Similarly, “keystone species” are animals that have a disproportionately large effect on the ecosystems they live in.

For example, Robert T. Paine first tested the keystone species hypothesis empirically (scientifically) by removing a species of starfish (Pisaster) from its intertidal habitat and observing the dramatic changes this removal wrought on the starfish’s prey, mussels (Mytilus) and the ecosystem as a whole.  It turns out that the starfish helped to keep the mussels’ numbers in check, and without the starfish to eat the mussels, the mussel population exploded and took over the habitat, crowding out other species and decreasing biodiversity (the numbers of different species in an ecosystem).

Keystone species can fall under several different categories.  Top predators, like the starfish, are often keystone species because of the inherent role they play by eating lots of smaller animals.  That’s why it’s so important to conserve large mammalian carnivores like lions, tigers, and bears – all endangered species – which unfortunately attract a lot of poaching due to their magnificent furs and sought-after meat.

arch1

Another category of keystone species are mutualists, which are animals that help many other species for something in return (in a mutually beneficial relationship).  For example, fruit trees are keystone mutualists because they provide shelter and food for many animals like monkeys and birds, which repay the tree by dispersing their seeds far and wide.

Finally, ecosystem engineers are keystone species because they are animals that change the physical landscape in which they live.  Beavers, elephants, and prairie dogs are all examples of ecosystem engineers because they build dams, destroy trees, and make burrows, respectively.

Prairie_Dog_closeup

Prairie dog (Cynomys)

Learning about these concepts helps scientists and environmentalists define categories in which to place animals and know which animals to target in conservation efforts.  It is far easier to conserve a whole ecosystem by protecting one species than by trying to protect the entire community of animals.  In this way, scientists use keystone species to protect Mother Nature, one animal at a time!

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References:

See No Ordinary World’s post on sea otters, another important keystone species:  https://thisisnoordinaryworld.wordpress.com/2013/03/06/sea-otters-adorable-endangered-and-a-keystone-species/.

Keystone species definition: http://animals.about.com/od/animalswildlife101/f/keystonespecies.htm.

“Keystone.”  Wikipedia.org.  http://en.wikipedia.org/wiki/Keystone_(architecture).

“Keystone Species.” Marietta.edu.  http://www.marietta.edu/~biol/biomes/keystone.htm.

“Keystone Species.”  Wikipedia.org.  http://en.wikipedia.org/wiki/Keystone_species.

“Mutualism.”  Wikipedia.org.  http://en.wikipedia.org/wiki/Mutualism_(biology).

Sea Otters: Adorable, Endangered, and A Keystone Species

Here_I_am.. sea otter baby sea otter

This cuddly creature is a sea otter, or Enhydra lutris, a well-known marine mammal native to the coasts of the northern and eastern North Pacific Ocean.  This furry, playful fellow is more than just adorable, however.  Otters are a keystone species.

In architecture, the keystone at the top of an arch holds the arch together.  Without the keystone, the whole arch and building surrounding it will collapse.  Similarly, some species of animals are called “keystone species,” meaning that a whole ecosystem, or interplay between living organisms and their surroundings, depends on that particular species to keep it running smoothly.

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Sea otters play a crucial role in their watery home.  How do we know?  Here’s the story:

In the 1700s, sea otters along the coast of California were hunted nearly to extinction for their furs and killed by fishermen who thought they were eating too much of the fish they wanted to catch.  When the otters disappeared, the animals they normally eat, sea urchins, enjoyed a large population boom.  Soon, there were so many sea urchins that they ate all of the kelp, a type of seaweed, at the bottom of the ocean, and caused an “urchin barren” to form, which means that the ocean floor is scraped clean and becomes an “ocean desert” in the ocean that is essentially devoid of life.  This is bad!  Fish raise their young in the protection of the kelp and other animals hide it in to avoid prey, and all those animals began to flee the scene as well. The fishermen now had less fish to catch, not more.  It turns out the otter was playing a much more crucial role in this ecosystem than people previously knew.

What happened to the otters?  In 1911, a treaty was passed to protect the sea otters from being hunted.  In some places, the populations of sea otters recovered, and eventually so did the kelp and fish.  But there are still some areas that have suffered near-permanent damage from the removal of just one type of animal – the sea otter – from its home.

Now, the sea otter is globally an endangered species, meaning that its numbers are so low that it is under imminent threat of becoming extinct, or dying out entirely.  The sea otter’s story shows us that if we take action we can achieve a remarkable success story that seems daunting, if not impossible, at first.

Sources:

“Here I am..” Top left photograph.  Photograph taken by Alan  Wolf and distributed under a Creative Commons License: CC BY-NC-SA 2.0

Baby sea otter photograph: sflo1822 on tumblr.

Three otters photograph: jamoore52 on tumblr.

Seat otter:  http://en.wikipedia.org/wiki/Sea_otter

Keystone species (definition): http://animals.about.com/od/animalswildlife101/f/keystonespecies.htm

Keystone species hypothesis: http://www.washington.edu/research/pathbreakers/1969g.html

Keystone species empirical evidence:  http://rspb.royalsocietypublishing.org/content/early/2012/07/03/rspb.2012.0856.full