Early life disadvantage strengthens flight performance trade-offs in European starlings, Sturnus vulgaris

Abstract

Developmental stress has been shown to affect adult flight performance in birds, with both negative and positive effects reported in the literature. Previous studies have used developmental manipulations that had substantial effects on patterns of growth. They have also examined mean levels of flight performance per individual, rather than investigating how developmental stress might alter trade-offs between different components of flight performance. We recorded multiple components of escape flight performance in 20 adult European starlings previously subjected to a manipulation likely to have altered levels of developmental stress. Siblings had been cross-fostered to nests where they were either slightly larger (advantaged treatment) or slightly smaller (disadvantaged treatment) than their competitors. The manipulation had no detectable effect on growth. However, developmental treatment affected performance in escape flights a year later by strengthening the trade-offs between different flight parameters. Disadvantaged birds faced a steeper trade-off between take-off speed and take-off angle, and a steeper trade-off between take-off angle and total time in flight, than advantaged birds. The results suggest that even subtle early life adversity that has no obvious effect on growth or size can leave a lasting legacy in the form of constraints on locomotor performance later in life.

Keywords: developmental stress; early life adversity; flight performance; locomotor performance; starlings.

Figure 1

The experimental arena. (a) Side view showing perch locations, measuring arcs and aerial maze. (b) Plan view indicating positions of the three cameras.

Figure 2

Between-bird means and SEs for each flight performance measure by developmental treatment. ADV: Advantaged birds; DIS: disadvantaged birds. (a) Take-off speed; (b) take-off angle; (c) number of strings hit; (d) time in flight.

Figure 3

Representation of the trade-off between take-off angle and take-off speed for individual birds by developmental treatment. (a) Advantaged birds; (b) disadvantaged birds. Each solid line segment represents the fitted relationship from a regression of take-off angle on take-off speed for the escape flights of one bird, plotted from its lowest observed speed to its highest. Birds with a single recorded flight are shown as a point. The dashed line represents the central tendency for the group and uses the median intercept and median slope.

Figure 4

Representation of the trade-off between take-off angle and total time in flight for individual birds by developmental treatment. (a) Advantaged birds; (b) disadvantaged birds. Each solid line segment represents the fitted relationship from a regression of time in flight on take-off angle for one bird, plotted from its lowest observed angle to its highest. Birds with a single recorded flight are shown as a point. The dashed line represents the central tendency for the group and uses the median intercept and median slope.