Thursday, February 16, 2017

House Sparrow

Old World Species Gets Scarcer

House Sparrow - Male
 The House Sparrow (Passer domesticus) was once a common resident of New Brunswick.  Its numbers have been declining since about 1970.  It was very common in the first half of the 1900s probably because it embraced agricultural communities and city environments in which horses were common.  It is an introduced Eurasian species and was first reported in New Brunswick in 1884.  It all started when eight pairs were released in Brooklyn, New York in 1851.  Several more releases occurred after that, some in the 1870s.  Other groups were captured and released in various places throughout the United States.  One reason this was done was to provide familiar wildlife for local residents who had come from Europe.

House Sparrows are a unique species and have several behavioural traits which set them up for success as an introduced species.  They prefer to live near human habitation.  This provides food and nesting sites and some protection from predators.  They are an active, aggressive species and can successfully compete for food and nesting sites with native species.  They nest before our native species arrive back in the spring so have their preference of nesting sites.  They have 2 or 3 batches per year of up to 5 offspring each.  These traits lead to rapid population increases.

House Sparrow - Female
The House Sparrow is a gray/brown short-legged sparrow.  It represents a different family from our native sparrows.  The male has a black bib, gray crown and brown band from the eye backwards across the neck.  The female is gray/buff with a buffy line over the eye.  In the non-breeding season the male's plumage becomes more brown-buff in colour with a buffy colour infringing on the bib and brown eye line.  Many of us remember the discordant 'cheep cheep' sound these birds make.  They definitely are not musical.

The range of this species covers all of North America and Mexico and extending northward into Labrador and Northwest Territories.  I was surprised recently to see pictures of them thriving in Churchill, MB.  Having Eurasian distribution, they are native to Britain, Scandinavia, Siberia, northern Africa, Arabia, India and Burma.  Because of introductions by humans they have become established worldwide almost everywhere except Antarctica.  Because of this their population is extremely large.  In Europe alone their population is estimated to be 270 million.

House Sparrow - Male, Non-breeding Plumage
House Sparrow - Female, Non-breeding Plumage
Why has our population been declining since 1970?  That is a question pondered by many birders.  This year is the first year we did not find any on the Mactaquac Christmas Bird Count.  Every year since its inception we have found this species around cattle barns.  Very few House Sparrows live in Fredericton now.  The decline is a worldwide phenomenon.  Scientists do not know exactly why this is happening,  It certainly would be multi-factorial.  The huge decrease in the number of farms, removal of horses from the streets, improvement in grain-harvesting efficiency, and use of insecticides would be some of the reasons.  It will be interesting to see what will be the final results of scientific investigations.  As much as many people dislike these spunky little sparrows, it is sad to see them decline so severely.

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