A summary of "Surviving in sprawling suburbs: Suburban environments represent high quality breeding habitat for a widespread shorebird"

The following summary was written by senior Katie Anderson.
----------------------------------------------------------------------------

Cardilini et al. (2013) Surviving in sprawling suburbs: Suburban environments represent high quality breeding habitat for a widespread shorebird. Landscape & Urban Planning 115: 72-80.

As urbanization across the United States has rapidly increased, researchers have begun paying greater attention to urban impacts on the environment. One such research study, carried out in 2010 on Phillip Island in South Victoria, Australia, compared the reproductive success in suburban and agricultural habitats of an avian species, the Lapwing, which has been proven to be able to live in both suburban and agricultural environments. Researchers Adam P.A. Cardilini, Michael A. Westona, Dale G. Nimmoa, Peter Dannb, and Craig D.H. Shermanc sought to investigate the correlation between increasing urbanization and decreased biodiversity, using the Lapwing as their species of study.  In this study, the Australian-located researchers looked at nest characteristics, incubation and brood attendance, parental defense, and fledgling success to assess the reproductive survival rates of Lapwings in suburban versus agricultural habitats. Two predictions were made entering into the study. Prediction number one stated that the quality of parental care would be higher in an agricultural habitat than a suburban habitat. Prediction number two stated reproductive success would be higher in agricultural habitats than in suburban habitats.

Masked Lapwing, Vanellus miles. Photo courtesy of Wikipedia.

The article on Lapwing survival explains “the concept of urbanization encapsulates a broad range of land-use changes, from the conversion of native vegetation to densely populated cities, to the transformation of agricultural environments to low density, suburban environments; the latter process being known as ‘urban sprawl’.” The Lapwing study sought to understand how those changes in land use impact local native species and their ability to successfully reproduce in the ever-increasing urban environments compared to the decreasing abundant agricultural natural habitats.

To measure the level of parental care, researchers looked at incubation, brood attendance, and parental defense measures. Incubation involves the mature Lapwings sitting on their eggs and warming them. Brood attendance refers to care after the chicks hatch. Parental defense measures were noted as how aggressive and attentive birds got when their nests and chicks were approached. By close observation, researchers determined that the number one significant indication of difference in parental care between agricultural and suburban environments was parental defense. Lapwings living in suburban habitats showed a higher level of aggression. Much to the researchers surprise, Lapwings in agricultural environments did not have a higher level of parental care. With these results, Cardilini and his team rejected their first prediction, which states that the quality of parental care would be higher in an agricultural habitat than a suburban habitat.

The second prediction of higher reproductive success in agricultural habitats versus suburban habitats was measured by monitoring hatching success of chicks from their eggs, as well as fledgling success. Out of 105 eggs in each habitat type, 76 hatched in suburban environments, and only 57 hatched in agricultural environments. Causes of failure for eggs to hatch include nest abandonment, human interference, nest depredation, crushed by stock animals, and other unknown variables. The researchers found that although there was more human presence in suburban habitats, more direct threats were experienced by the Lapwings in agricultural settings, primarily that of other non-human predators and stomping from stock animals. The difference in eggs hatched was the most significant indication that there is disparity between suburban and agricultural habitats for reproductive success. With these results, the second prediction, which stated reproductive success would be higher in agricultural habitats than in suburban habitats, like the first, was rejected.

Although there have been other studies and statistics that have shown increased urbanization has led to decreased biodiversity worldwide, the study on the Lapwing birds did not do much in support of this claim. In response to their study results, the researchers made a point that “species that benefit from urbanization are the exception rather than the rule.” They also commented that species such as earthworms, which Lapwings commonly eat, are an exceptional species that thrives in urban settings. This change in food availability for the Lapwings very well could have influenced the mature Lapwing healthy condition, which in turn impacted the success of their hatchlings. Cardilini and team stressed, “the predictions we made at the outset of this study require further testing on a variety of species; their lack of application described here cannot be generalized.” What the research team is stressing here is important for everyone to take note of. The impact urbanization has on species biodiversity is a real concern, altering the lived experience of plants and animals, including humans, and should not be ignored. There will undoubtedly be further studies on this emerging topic of concern.