If you build a campground, jays will come
To people, camping in the midst of California’s giant redwoods – the tallest and some of the oldest trees on the planet – offers an unparalleled chance to get away from the human world and experience nature.
To wildlife, a campground – even one set amongst majestic redwoods – is the human world. And this form of the built environment, though it looks relatively rudimentary, affects wildlife behavior just as surely as a skyscraper or a highway does.
In a recent study in conducted in Redwood National and State Parks, researchers led by Will Goldenberg of Humboldt State University demonstrated this by fitting 30 adult male Steller’s Jays with radio transmitters and tracking their locations over the course of a summer. Twenty of the birds came from two popular campgrounds and the remaining 10 individuals were captured in parts of the forest away from human use.
Altogether the researchers amassed 2,806 daytime locations (an average of nearly 86 observations per bird) and 195 roost locations for the birds over the course of the study. Campground jays and non-campground jays have similarly sized home ranges, they reported recently in The Condor: Ornithological Applications.
But the home ranges of campground jays overlap more than do those of non-campground jays, suggesting that the abundance of human food around campsites makes the birds less territorial. The researchers also observed up to 15 jays foraging in close proximity within campgrounds, largely without squabbling with one another.
Campgrounds jays spent more time within a meter of the ground than did non-campground jays, the better to cadge unattended morsels from picnic tables, fire pits, dishwashing areas, and trash bins. (We humans are the low-hanging fruit – or at least, we provide it.)
Campground jays also gave the impression of enjoying life on easy street, spending more time perching and less time foraging compared to birds that inhabit areas farther away from human activity.
The home range overlap among campground jays means that jays reach higher population densities in campgrounds than elsewhere in the forest. Some closely related species of birds, such as Common Ravens, are less unfazed by human activity and do not make much use of campground food sources.
In other words, when we go out into ‘nature,’ our casual observations of which wildlife species are commonest are often distorted by our own presence in the habitat.
But the results of the study are important for reasons beyond philosophical pondering. All of the areas included in the study, including the two campgrounds, are breeding areas for the Marbled Murrelet, a federally threatened seabird species.
Steller’s Jays sometimes prey on murrelet eggs when they encounter nests while foraging for other foods. Since murrelets nest high in the forest canopy, and campground jays spend a lot of time near the ground, campgrounds could ease this predation pressure by reducing the probability that a jay will encounter a murrelet nest.
On the other hand, the researchers say, the increased population density of Steller’s Jays around campgrounds could make Marbled Murrelet eggs more vulnerable to predation overall. – Sarah DeWeerdt | 19 July 2016
Source: Goldenberg W.P. et al. “Steller’s Jay (Cyanocitta stelleri) space use and behavior in campground and non-campground sites in coastal redwood forests.” The Condor: Ornithological Applications DOI: 10.1650/CONDOR-15-187.1
Header image: A Steller’s Jay steals a peanut in a campground in Redwood National and State Parks. Credit: W. Goldenberg.
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