Wednesday, March 30, 2011

The importance of feathers

All birds have feathers and any animal with feathers is a bird.

Haven't been able to find the original author of this quote but it makes the classification of Aves pretty clear doesn't it?

Feathers are complicated structures. An evolutionary marvel.

The original pressure to adapt such an accessory was for warmth. Flight came much later. The insulating properties of feathers allow birds to live in the coldest and hottest environments that few other creatures can tolerate. Think of penguins in Antarctica or ostriches in the Sahara desert.

A different kind of bond between keratin protein strands in the feathers, beaks and claws of birds give them a greater toughness than the keratin parts of mammals (i.e. hair, horns, and hoofs).

The many colours seen in bird plumage come from either pigments absorbed from the diet or the microscopic refractive structures.

The arrangement of microscopic structures in combination with a certain angle of light give many species spectacular iridescent plumage. 

The bright whites of seagulls and egrets come from air trapped between feathers that scatters all the wavelengths of light. 

Illustration by Adolphe Millot (1857 - 1921)
In some species the growth of wild feathered appendages would seem to put them at a disadvantage by either making them very visible to predators or too clumsy to escape. 

Evolutionary biologists puzzled over this until they realized that the outlandish diplays signalled to potential mates what high quality genes must be carried by an individual that survives despite such an obvious handicap.

Thursday, March 24, 2011

An oystercatcher by any other name

The black oystercatcher is not quite correctly named.

It could be called the black limpetcatcher, or the black musselcatcher to be more accurate in terms of what this shore bird eats.

Described as "just plain comical" by Nancy Baron and John Acorn in their Birds of Coastal British Columbia guide book, some researchers are taking this bird seriously.

The Pacific Wildlife Foundation and Parks Canada selected the bird as an indicator species of rocky intertidal community health.

To start that meant learning all about populations and movements to get a baseline measure. It is already known that the species is not threatened. The global population is around 10,000 individuals. Most live in British Columbia and Alaska.

They forage along rocky shores, often in urban settings, making it a good species for measuring the effects of human disturbance. 

This fellow at left was boldly stalking the shores of a beach in Sidney, just north of Victoria. About 100 pairs nest in the Strait of Georgia between Vancouver Island and the mainland.

To get the local population data, many birds were banded. Researchers hope people will report sightings here.

Haida Gwaii oystercatchers have orange or dark blue bands on their left leg.
Pacific Rim National Park birds have white bands with black letters on the right leg.
In the Gulf Islands they have orange bands with black letters.
BC mainland coast oystercatchers have yellow bands with black letters.

If you see a banded oystercatcher, note the band colour and numbers (if visible) and your location.

Thursday, March 17, 2011

Clip from Bird Studies Canada

11 March 2011 – A few weeks ago, the oldest known wild bird in the Northern Hemisphere was spotted at Midway Atoll National Wildlife Refuge in Hawaii. The bird, a female Laysan Albatross named Wisdom, is at least 60 years old; she is also a new mother. 

   Wisdom was spotted with her chick a few weeks ago by John Klavitter, a U.S. Fish and Wildlife Service biologist and the deputy manager of the Midway Atoll National Wildlife Refuge. She has sported and worn out five bird bands since she was first banded by U.S. Geological Survey (USGS) scientist Chandler Robbins in 1956. At the time, he estimated the albatross to be about five years old. Robbins rediscovered Wisdom in 2001, when she was at least 50. 

   “She looks great,” said Bruce Peterjohn, the chief of the North American Bird Banding Program at the USGS Patuxent Wildlife Research Center in Laurel, Maryland. “And she is now the oldest wild bird documented in the 90-year history of our USGS Fish and Wildlife Service and Canadian bird banding program,” he added. “To know that she can still successfully raise young at age 60-plus, that is beyond words. While the process of banding a bird has not changed greatly during the past century, the information provided by birds marked with a simple numbered metal band has transformed our knowledge of birds.” 

   Wisdom, Peterjohn said, has likely raised at least 30 to 35 chicks during her breeding life. Almost as amazing as being a parent at 60 is the number of miles she has likely flown. Adult birds average about 50,000 miles annually, so Wisdom has flown at least two to three million miles since she was first banded. That’s the equivalent of four to six trips from earth to the moon and back again, with plenty of miles to spare.

Tuesday, March 08, 2011

Have you seen this bird?

It's British Columbia's most widespread and abundant warbler.

A small number of these hearty songbirds overwinter on Vancouver Island. A pocket population socks in on Stubbs Island near Tofino, B.C. where a forest of California wax-myrtle provides them with food and shelter. It's the only place the plant grows on Vancouver Island.

The berries are purple, contain a single seed and have a white wax coating. They are unusual in that the fruit ripens late in the fall, providing a bounty of calories in the winter when other plants are dormant. If the bushes were removed, the birds could not stay.

Each time we cut a tree, hack a bush, pull up a plant the little community of organisms that depend on it have to find a new home or source of food. When we need we should harvest. When we don't, we should leave it for the other species that live on this planet.

Tuesday, March 01, 2011

Amazing tales from nature

I read a lot of comic books as a kid. Well, as an adult too. Giant grasshoppers and runaway tomatoes are imprinted on my brain.

Giant kelp is a real life plant, or algae, that lives up to the comic book hype.

Giant kelp and bull kelp are two characteristic species of algae on this coast. They wash up on the beach when they die and become whips in the sandy adventures of kids walking the shores.

Giant kelp grows an average of 27 cm per day in the spring. It can grow as much as 61 cm in 24 hours. That's two feet!

These tree-like algae form underwater forests where invertebrates, fish, marine mammals and birds find food and shelter. Even grey whales hide from killer whales amongst the stipes.

The popular image of a sea otter (not to be confused with the much more common river otter that is seen in the ocean around southern Vancouver Island) lying on its back, surrounded by kelp with an urchin between its paws illustrates and interesting interrelationship between those three species.

Sea otters were nearly wiped out in this coast in a hunting frenzy for their pelts in the 1800s. When their numbers were reduced, the kelp forests nearly disappeared. This was because the favourite prey of the otters - sea urchins - expanded their populations rapidly once they were free of their furry predators. The urchins eat the kelp and devoured the forests up and down the coasts.

It's one of the classic examples of a keystone species. An animal that may not be the most numerous, or obvious, but if removed from an ecosystem has a big impact.

All species have some function in their environment. Most of the time we do not see it, or understand it or make any decisions based on it.