Number of trees that had at least one artificial larva with marks of avian predation when the tree contained an <i>Operophtera brumata</i> pheromone dispenser and when the tree contained a control dispenser.

<p>Number of trees that had at least one artificial larva with marks of avian predation when the tree contained an <i>Operophtera brumata</i> pheromone dispenser and when the tree contained a control dispenser.</p

Photograph of the pheromone dispenser and several plasticine caterpillars, one of them with beak marks, indicating a predation event by an insectivorous bird.

<p>Photograph of the pheromone dispenser and several plasticine caterpillars, one of them with beak marks, indicating a predation event by an insectivorous bird.</p

Statistics.

<p>Statistics and significance levels of loss of body weight, resting metabolic rate, and mean body temperature of male and female great tits exposed two times during the night to the scent of a predatory mammal (mustelid) or a non predatory mammal (rabbit) in a respirometry chamber at 10°C.</p

Respirometer Schema.

<p>Schematic representation of the respirometer used in the experiment. From left to right: carbon dioxide and humidity are removed from inlet air thanks to a column containing one layer of Ascarite (A) surrounded by two layers of Drierite (D). Pumps force the air in three different circuits: i) a reference circuit (top) containing an empty chamber used to calculate the amount of oxygen used by the birds in the other chambers, ii) a second circuit (middle) leading to the three chambers containing the birds exposed to predator (ferret) odour, and iii) a third circuit (bottom) leading to the three chambers containing birds exposed to the control (rabbit) odour. In each of these two last circuits, a first valve lead the inlet air either in a compartment containing the urine-damped filter paper, or a compartment containing a dry, odourless, filter paper. A flowmeter setting the flow rate to 250 ml min⁻¹ precedes each animal chamber. A second set of valves, installed after each animal chamber, controls from which chamber the oxygen concentration is measured.</p

Weight loss and Resting Metabolic Rate.

<p>Mean ± SE <b>a</b>) Loss of weight (g) and <b>b</b>) Resting Metabolic Rate (KJ 24 h⁻¹) of great tits exposed to predator scent or to control scent during the night in a respirometry chamber at 10°C.</p

Oxygen Consumption and Body Temperature.

<p>Mean ± SE <b>a</b>) Oxygen consumption (ml O₂ min⁻¹) and <b>b</b>) Body temperature (°C) of great tits before (odourless control) and during the exposition to predator scent (treatment: predator (mustelid, full squares) or odorous control scent (rabbit; open circles) at the beginning of the sleeping period (first exposition, 30 minutes after being introduced in the respirometry chamber) and five hours later (second exposition).</p

Number of females choosing their own or a foreign nestling scent.

<p>Number of female spotless starlings that chose the side of the chamber containing the scent of their own nestling or the scent of a foreign nestling (p = 1.00), when a) nestlings were 5–6 day old and have the uropygial gland closed or b) when nestlings were 12–14 day old and have the uropygial gland open.</p

Schematic representation of the olfactometric device used.

<p>A focal female was introduced into the central chamber and exposed to scent-carrying air flowing in (solid arrows) from the choice chambers. Odour donor nestlings were hidden from the focal female's view behind a dense plastic mesh (fine cross hatching). A choice was scored when the female entered one of the choice chambers after opening the doors (dotted arrows).</p