House Sparrows And Starlings Are Super Competitors
Like it or not, house sparrows and starlings are super competitors; they were born to rule. From small introduced flocks, they have spread like an avian plague across North America, out competing many of our native hole nesting birds. The starling, in particular, has proven itself to be the master of nearly every native hole nesting bird it confronts. How and why have such European imports been so successful in competing with our native birds from such humble beginnings?
Aggressive, persistent, well-armed physically, and endowed with an unbelievable instinctive drive to procreate, they are formidable adversaries. Evolution has been kind to the house sparrow and starling and has created two of the most successful bird species known to mankind.
The house sparrow is about 5 inches long and doesn’t look that intimidating. But looks are deceiving. The house sparrow is armed with a heavy, conical finch beak that can crush like a miniature vise. It is pointed and has a sharp edge used to crack seeds and inflict damage on weak bill birds like tree and cliff swallows and bluebirds. Swallows, in particular, have short bills with a wide gape. Their bills are relatively soft and rich in sensitive nerve endings. Such bills have limited crushing attributes and are no match in beak to beak confrontations with the vise-like grip of the house sparrow’s bill. House sparrows can severely injure and even kill swallows and bluebirds by crushing their soft bills, pecking out their eyes, and literally scalping them.
Purple martins, though swallows, are a different proposition and can often successfully defend their nests from house sparrows even though the sparrows have more powerful beaks. The purple martin has a larger and stronger beak than other swallows as it is used to capture bigger insects like dragonflies and the martin is larger than the sparrow. Martins are aggressive in defending their nest sites and such aggression and size can matter, particularly when intimidating an opponent! At established sites where martins have strong site tenacity and greatly out number any sparrows that are nesting or attempting to nest, martins can often hold their own and even keep sparrows at bay; at un-established sites, sparrows can easily chase away any martins that may visit. The martin’s larger size and aggressive behavior often initially intimidates house sparrows, particularly at established sites where martins have nested for many years. However, aggressive sparrows may eventually force their way into a martin colony and establish territory in vacant cavities. Martins are no match for aggressive sparrows in beak to beak confrontations as the sparrow’s crushing beak is a superior weapon. Yet, house sparrows are often reluctant to battle with the larger martins at close quarters and martins often prevail in conflicts inside the nests. House sparrows mainly adversely impact martin colonies by clogging up houses/gourds with almost martin-proof nests. House sparrows build a nest that is compactly constructed and contains a narrow tunnel entrance that leads to the nesting chamber. Such a nest that is so tightly packed in a house compartment or gourd may readily exclude the larger martin from easily entering. Sparrows can evict martins by simply filling the house/gourds with their nearly martin-proof nests; no fighting necessary! Sparrows can build a nest in record time and will build it over a martin’s nest when the martins are not there; in a few days the martins may not be able to enter their nest. At unmanaged colonies sparrows can seriously reduce the occupancy level by martins when the sparrows build their nests at will and no landlord removes them. Sparrows also sneak into unguarded martin nests and destroy eggs and kill recently hatched young.
The starling is about 8 inches long and is a virtual killing machine, an avian terminator. Armed with a dagger like beak, powerful long legs, sharp claws, and a muscular body, the starling is truly the super competitor. Purple martins, bluebirds, woodpeckers, house sparrows and other hole nesting birds are usually no match for starlings in combat at close quarters inside the nest cavity. On occasion, a determined flicker or other woodpecker will successfully defend its nest against starlings, but starlings usually reign supreme, particularly inside the nest cavity. Even large flickers are usually severely beaten by starlings in close quarter battles and I have seen screaming flickers hanging halfway out of a hole while a starling holds his victim from behind. Great crested flycatchers, in defense of their nests, will viciously attack and drive starlings away in open combat, but are no match in fighting starlings inside the nest. Starlings possess a killer instinct and will readily kill weaker birds, like purple martins, in ferocious battles inside the nests. The starling will grip the martin in its claws, hold it down, and savagely peck at the martin’s head and eyes. Few martins can escape the raptor like clutches of the starling and they may be killed or injured. Starlings will also destroy martin’s eggs and kill their young.
Starlings and particularly sparrows may remain in their territories year round and even roost in their old nests. I have seen chirruping sparrows on old martin houses in the dead of winter. Starlings and sparrows are usually looking for nest sites weeks before many native species are doing so and will claim them. By the time migratory native species have “returned home”, many of their older nest sites have already been taken over by starlings and sparrows and they are firmly bonded and aggressively fight to hold the territory.
Starlings are intimately familiar with the nesting habits of woodpeckers and will “watch” a pair of woodpeckers excavate their nesting cavity. Fresh woodpecker cavities are a favorite nest site for starlings; starlings frequently “investigate” dead trees/limbs in search of woodpecker holes. As soon as the cavity is large enough, the starlings start attacking and harassing the woodpeckers until the woodpeckers are driven off. And there is a possible reason for the starling’s “knowledge” of woodpecker nesting behavior as described below.
But there is more to the success of house sparrows and starlings in competing with our native hole nesting birds than brute force and aggression. They already had the genetic knowledge and behavioral mechanisms for competition in place when they were first released in America over 100 years ago. Think about the following. In their native home land of Europe and parts of Asia, both house sparrows and starlings have been competing for thousands and thousands of years with other hole nesting birds. And guess what? They have for the most part proven to be super competitors here, too! House sparrows out compete house martins and evict the weak billed martins from their mud-domed nests. House martins are similar in size to our tree and cliff swallows. However, house sparrows are not so successful in competing with the common swift which nests in holes. The common swift, though possessing a weak bill, is larger, aggressive and nearly as big as our purple martin and fights back. Interesting comparisons! Starlings may evict European woodpeckers, like the green and greater spotted woodpeckers from cavities. The green woodpecker is similar in size to our flicker and the spotted woodpecker is similar to our red-headed and red-bellied woodpeckers. More interesting comparisons!
So it appears that house sparrows and starlings had thousands of years of successful competition with other hole nesting birds in their native home land of Europe and Asia. When they were introduced in North America, they adapted perfectly and applied their powerful physical weapons, aggressiveness, and genetic knowledge to compete with native hole nesting birds. What worked with European house martins and woodpeckers for thousands of years also worked with American swallows and woodpeckers. House sparrows and starlings are truly super and, yes, intelligent competitors and just did and are continuing to do what is naturally programmed in their genes–they are continuing their species in an incredibly successful manner.
The introduction of house sparrows and starlings in North America is a premier example of the folly of humans adversely impacting the ecology of an entire continent. North America with its diverse geography, huge territorial expanses, many urban/suburban locations, various climate ranges, and numerous potential nesting sites provides the ideal environment for house sparrows and starlings to breed successfully and expand their range. The North American environment, particularly the urban/suburban complexes, is similar in some ways to parts of Europe and Asia and these species were able to easily adapt and prosper. Our malls, fast food establishments, farms, golf courses, backyard bird feeding stations, and closely mowed lawns in suburbia and city parks are ideal environments for house sparrows and starlings. House sparrows look for scraps and dropped human food items around businesses while starlings use their long beaks to probe for invertebrates in the short grasses of lawns.
Though North America has predators such as Accipiter hawks, merlins, peregrine falcons, owls, and rat snakes, house sparrows and starlings were first introduced in more urban areas where such predators are not as common. From this urban base, house sparrows and starlings were able to breed successfully, build up a huge population, and gradually expand their ranges to other cities and towns with limited predation pressures initially. Of course, predators, particularly Accipiters, began to exploit this huge burgeoning prey biomass, but by then house sparrows and starlings were so entrenched and numerous, that predation would be unable to limit their numbers sufficiently to provide any ecological balance. The avian plague of house sparrows and starlings was able to spread and infect nearly all areas of North America through the sheer force of numbers and the various predators were unable to help keep this pandemic under control.
In their native home land of Europe and parts of Asia, house sparrows and starlings are preyed upon by sparrow hawks (similar to our sharp-shinned and Cooper’s hawk), merlins (we have merlins, too), hobbies (extremely swift falcon, something like a miniature peregrine falcon), peregrines (we have them, too) and owls (we have great horned, barred and screech). This predator/prey relationship in Europe and Asia has evolved over thousands of years and a balance exists to a certain degree and helps keep house sparrow and starling population numbers in check.
Also, some European cavity nesters like greater spotted woodpeckers may nest later in the season to minimize competition pressure with starlings which typically breed earlier. And European woodpeckers will retreat to more wooded areas to nest and starlings do not usually breed in such locations. Some of our North American woodpeckers may be able to breed later after most of the starlings have finished nesting and this nesting behavior has helped flickers and red-headed and red-bellied woodpeckers to a degree to nest successfully in starling infested areas. And red-bellied woodpeckers in particular will nest in forests which are often not favored by starlings.
European house martins will construct their mud-domed nests in dense colonies under roof overhangs of buildings and nesting in large numbers may provide insulation from competition from house sparrows though sparrows can still evict some martins but not all. Additionally, house martins can build new homes if their first ones are usurped by house sparrows.
And finally, house sparrows and starlings may be more subject to periodic significant population declines in parts of Europe which is smaller in geographical size than North America. Any species that is concentrated in a smaller area would probably be more vulnerable to widespread adverse environmental factors. Currently house sparrow and starling numbers are declining in Europe. Scientists speculate that changes in farming practices that reduce left over grain as a food item, new human house/building construction designs that eliminate potential “cavities” in roofs, and increases in sparrow hawk numbers have contributed to the demise of house sparrow and starling populations. Perhaps similar scenarios have occurred in the past to reduce house sparrow and starling populations periodically which has helped keep these species in balance with others in Europe.
We, as responsible purple martin landlords, must vigilantly eliminate both house sparrows and starlings from our martin colonies and not let these super competitors nest in our yards. They are highly destructive competitors that adversely impact our native hole nesting birds like purple martins, tree swallows, bluebirds and woodpeckers.
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300+ pairs of martins each season
300+ pairs of martins each season
This was a good read. And reminder of when I look into that cute face of the sparrow why I do what I do. Not to be fooled. I also think they adapt so well with eating people food nesting anywhere. Sparrows make their own cavitys in my pine trees with a bunch of nest material. And they will nest in close proximity to each other. On like the blue bird. I hate when I go threw a town of ran down houses and I see them nesting every where in whatever they can get in. I think all towns should have a trap. This needs to get on a voting ballot. Why are we as people not caring or doing anything? These birds are like cockroaches. And stray cats.
2008 first year 1 pair. 2009 3 pair. 2010 7 pair. 2011 20 pair . 2012 44 pair 280 eggs 210 fledged. 2013 67 pair. 2014?