While I probably should not admit to it, my wife and I do make use of those amazingly low prices at our local Costco store. Yes, I am aware that some folks get sucked in and engage in rampant purchasing of things they don’t need, but we are, at least, smart about it. Besides the great deals, there is one other thing that I can always count on seeing at Costco, at least in western North America where I now reside --- lots of Brewer’s blackbirds strutting about the parking lot. I had initially surmised that they were there to climb up into the front of vehicles and glean dead insects off the radiators like some other songbirds have been observed to do (see below), but after some casual observations, I realized that they are scrounging for dropped food bits from customers munching on the various inexpensive snacks sold over the counter at Costco. And if some kind soul throws them a crumb or two, they won’t refuse it. Upon perusing the scientific literature on this species, it turns out that Brewer’s blackbirds are regulars in a large number of shopping mall parking lots all through its range, with Costco being among their favorite haunts.
My guess is that Brewer’s blackbirds do not suffer from ‘object neophobia’ or a fear of novel objects. No, I had not heard of the term either, that is until it showed up in an interesting paper in the June 2016 issue of the journal, Animal Behaviour. Alison Greggor in the Department of Psychology at the University of Cambridge in the U.K. and her colleagues examined this behavior in several corvid species and a number of non-corvids visiting platform feeders (the British call them ‘bird tables’).
You see, as we humans continue to drastically alter habitats on the earth, how fast birds can respond to novel stimuli may alter their chances of survival. The extent to which they do this can be good or bad for them, depending on what the item is. If it is dangerous, e.g. harbors a toxin or predator, then having a high level of object neophobia is useful. But if they are missing out exploiting something of value to them, e.g. a food item, they are hindering their success.
Past studies have shown that less neophobic birds more quickly interact with and solve novel foraging tasks, and in some avian species that inhabit a wide variety of habitats, specifically common mynas and house sparrows, those dwelling in urban environments are less neophobic and generally faster at solving tasks than their rural cousins. The best example I can think are those house sparrows in Australia that learned to trigger photoelectric doors of an airport lounge to gain access and feed upon crumbs on restaurant tables. At the same time, one has to consider the other side of the coin. Living in a human-altered habitat can present a number of life-threatening situations, e.g. exposure to novel predators or poisons, where having a high level of object neophobia can prolong one’s life. In that same species of sparrow, it has been documented that urban birds demonstrate higher levels of object avoidance than their rural counterparts. This has also been reported for shiny cowbirds.
So Greggor and her team presented free-flying bird communities with three kinds of objects:
1) natural items that mirrored natural stimuli (rocks, leaves or sticks found in that area)
2) litter items that represented food items in urban areas (man-made food wrappers such as potato chip bags, jam jars, styrofoam food packages, etc.)
3) novel objects built out of colorful, shiny artificial materials that did not resemble any naturally occurring shape or animal and contained no parts resembling eyes. They did this by establishing twelve bird tables in distinct geographical regions across the east and southwest of England with varying human population sizes that were representative of an urban and a rural habitat.
The study focused on five European corvid species: jackdaws, jays, rooks, magpies and crows, and seven non-corvid species: blue tits, great tits, European robins, common blackbird, common wood-pigeon, common chaffinch and house sparrow. Greggor and her colleagues were particularly interested in the corvid species if only because this group of birds has been shown to be paradoxically highly neophobic of foreign objects but also highly innovative in exploiting novel food sources.
To aid the study, a goodly number of these birds had been previously captured and leg-banded for identification. Moreover, before presenting the various objects, peanuts were offered to the birds to get them accustomed to visiting the feeding stations.
Greggor and associates predicted that:
1) the corvids would demonstrate a higher level of neophobia than non-corvids towards novel objects within habitats
2) both sets of species would reduce their neophobic behavior in urban areas towards objects that would be less novel there, e.g. litter
3) foraging birds would be more likely to approach objects after a member of their own species visited first.
Of the 77 experimental trials run, the team recorded a total of 4,300 visits to their bird tables whereupon 15,245 pieces of food were consumed. All five corvid species and all seven non-corvid species participated. Since the corvid visits were generally very brief, their presence did not deter the other species from attending the bird tables.
So what did they find? First, corvids were significantly more neophobic than the other species in avoiding tables bearing any one of the three kinds of objects, but were selective in how they responded to object types after a member of their own kind table foraged at the table first. In short, while corvids were willing to visit a table after one of their kind ‘broke the ice’, so to speak, they definitely ate and visited less at tables containing novel items. Second, there was no reduced neophobia in urban birds, as responses toward novel objects were similar in both habitats. However, both corvids and non-corvid groups arrived faster at tables bearing litter items in urban than rural areas. This likely reflects a specific reduction in fear toward a commonly occurring type of object.
Greggar and her team concluded that the corvids’ sensitivity to novelty was so obvious that the presence of new objects on familiar feeding tables, even natural materials that they may have encountered every day, reduced their probability of visiting tables. This should not be surprising, considering the fact that corvids are classified as vermin under U.K. law and are commonly and regularly targeted by various deterrents and culling efforts even in urban areas. On the other hand, the smaller songbirds or non-corvids represent birds that humans actively encourage to feed in their yards. In the U.K., no less than 60 percent of households with gardens provide food for wild birds.
How does all this fit with the corvids’ well known high rates of behavioral innovation? Well, we do not yet know how their neophobia subsides to allow them to manipulate and solve problems, but these highly intelligent birds seem to be able to rapidly learn to categorize novelty as ‘safe’ or ‘unsafe’. A number of studies have previously shown that corvids are able to recognize the faces of ‘dangerous’ humans or known versus unknown predators. The fact that the corvids in Greggor’s study had no problem visiting feeders containing natural and litter items but were less likely to do so at feeders bearing novel objects suggests that they were able to use social cues to classify objects as novel or safer according to their degree of novelty. This would explain why corvids can be so neophobic but at the same time, highly innovative around objects with which they have had prior experience.
With a human population of 7 billion and counting, and more and more wild habitat being turned into suburban and urban habitat, it becomes imperative that more studies on neophobia in birds must be done to better understand its importance in conservation and wildlife management contexts.
On a somewhat related note to all of the aforementioned, I was intrigued by an observation reported in the June 2016 issue of the Wilson Journal of Ornithology. It refers to the use of automobiles as shelter by the ubiquitous house sparrow. In the winter of 2015, Laure Cauchard and Thomas Borderie of the Department of Biological Sciences at the University of Montreal recorded on two different days a group of house sparrows sheltering under the fenders of several cars, i.e. in those empty spaces between the wheels and the fenders. Interestingly, the cars were located 10 to 15 feet from the bushes where the birds usually sheltered. On February 2, the day was bitterly cold (1 degree F) and snow (about 4 inches), while on April 13, the day was warmer (50 degrees F) but rainy. In each case, about 4 to 5 birds were involved and it was their endless chatter that attracted the attention of Cauchard and Borderie.
After ruling out the possibilities that the sparrows were inside the fenders looking for insects in other parts of the vehicles, as has been reported previously in this species, or gathering grit from the tires or inside fenders to aid in digestion, the authors are confident in proposing that the birds were simply using the unusual shelter as a means to avoid inclement weather, i.e. cold, snow and rain. And if the vehicles in question had been recently used, the warmth from the engine might have added even more to the birds’ comfort. Their constant flitting back and forth between the cars and the nearby bushes is suggested by the authors to be sentinel behavior whereupon the birds are simply keeping a vigilant eye out for cats, humans, and the like.
As much as many North American bird-lovers might despise the invasive house sparrow for out-competing native species for nest cavities, its street smarts are something to be respected. A total of 41 examples of innovative behavior have been reported for the house sparrow, but this is the first time one has involved a non-feeding activity, in this case sheltering under an automobile. Furthermore, while this behavior might well have been observed by others previously, Cauchard and Borderie were not able to find any published information on any bird species using a vehicle as shelter from bad weather. With that in mind, they encourage bird-watchers to publish anecdotes of behavior that they believe to be highly unusual or never seen before. It’s the kind of material that ends up in this column.