If I have to choose a favourite summer passerine, I would go with the Eastern Kingbird, partly because there are so many to study in the marsh/arboretum near home, but mainly because their so friendly and cooperative. I greatly admire the character of this species—determined yet laid back, excellent mates, and devoted parents. Watching them build their nests and raise their broods between May and July is an annual treat. Less colourful than Robins, perhaps, but elegant and proud to a greater degree. The more I observe them, the better I’m able to identify individual idiosyncrasies that endear some even more than others. Last summer we were treated to four pairs in Thomson Marsh, fairly evenly spaced around the walking path that borders Thomson Brook on the south and eastern sides of Mission Recreational Fields. Three of the four pairs successfully raised youngsters. Sadly, the pair that began the latest and that built what I thought was the most luxurious nest, had it destroyed by predators after the young had hatched. I didn’t see which predator, but I suspect magpies. It was very sad to see the adult birds, completely at a loss the day after the predation, hanging around in the area but too late in the season to make another attempt….
Sometime in the future I’ll write a post that follows the progress of the EAKIs’ summer….
Another “E” bird that is becoming more common in our neighbourhood is the European Collared Dove, an invader introduced into the Bahamas from Asia. When several ECDOs escaped captivity there in 1974, some found their way to Florida. Wikipedia tells the story below, but first, this important admission:
NOTE: Although DOVES ARE NOT CONSIDERED PASSERINES, I have included one here because it doesn’t fit into the other broad categories that I’m using. This is NOT intended to be a scientific blog; it’s a highly personal one. Please don’t get too bent out of shape by this issue.
“The collared dove is not migratory, but is strongly dispersive. Over the last century, it has been one of the great colonisers of the bird world. Its original range at the end of the 19th century was warm temperate and subtropical Asia from Turkey east to southern China and south through India to Sri Lanka. In 1838 it was reported in Bulgaria, but not until the 20th century did it expand across Europe, appearing in parts of the Balkans between 1900 and 1920, and then spreading rapidly northwest, reaching Germany in 1945, Great Britain by 1953 (breeding for the first time in 1956), Ireland in 1959, and the Faroe Islands in the early 1970s.
Subsequent spread was ‘sideways’ from this fast northwest spread, reaching northeast to north of the Arctic Circle in Norway and east to the Ural Mountains in Russia, and southwest to the Canary Islands and northern Africa from Morocco to Egypt, by the end of the 20th century. In the east of its range, it has also spread northeast to most of central and northern China, and locally (probably introduced) in Japan. It has also reached Iceland as a vagrant (41 records up to 2006), but has not colonised successfully there.
In 1974, less than 50 Eurasian Collared Doves escaped captivity in Nassau, New Providence, Bahamas. From the Bahamas, the species spread to Florida, and is now found in nearly every state in the US, as well as in Mexico. In Arkansas, the species was recorded first in 1989 and since then has grown in numbers and is now present in 42 of 75 counties in the state. It spread from the southeast corner of the state in 1997 to the northwest corner in 5 years, covering a distance of about 500 km at a rate of 100 km per year. This is more than double the rate of 45 km per year observed in Europe.
Interestingly, as of 2012, few negative impacts have been demonstrated in Florida, where the species is most prolific. However, the species is known as an aggressive competitor, and there is concern that as populations continue to grow, native birds will be outcompeted by the invaders. However, one study found that Eurasian collared doves are not more aggressive or competitive than native mourning doves, despite similar dietary preferences.
Population growth has ceased in areas where they’ve been established the longest, such as Florida, but is still growing exponentially in areas of more recent introduction. Carrying capacities appear to be highest in areas with higher temperatures and intermediate levels of development, such as suburban areas and some agricultural areas.
While the spread of disease to native species has not been recorded in a study, Eurasian Collared Doves are known carriers of the parasite Trichomonas gallinae as well as Pigeon Paramyxovirus. Both Trichomonas gallinae and Pigeon Paramyxovirus can spread to native birds via commingling at feeders and by consumption of doves by predators. Pigeon Paramyxovirus is an emergent disease and has the potential to affect domestic poultry, making the Eurasian Collared Dove a threat to not only native biodiversity, but a possible economic threat as well.”
Finally, another species introduced from Europe that has now spread throughout North America—the European Starling. From a distance, their unattractive profile often provokes the “Oh, it’s just a Starling” response. Occasionally, when a large flock flies as a murmuration, they can be quite entertaining. But every so often, we get close enough to see a mature adult’s special colours and pattern, and we’re reminded that it’s usually a good idea to be fully informed before we jump to conclusions….