Bud‐eating by bullfinches, Pyrrhulapyrrhula in relation to the chemical constituents of two pear cultivars

Abstract

S U M M A R YDamage to pear trees of the cultivars Conference and Doyenne du Comice caused by Bullfinches feeding on the flower buds was measured during January-April 1981. Bud-eating was concentrated on trees near woodland, and occurred at a steady rate within each row, though progressively more rows were attacked. Levels of total soluble protein, free amino acids, starch, glyceride-glycerol, fructose, glucose and phosphorus were low until mid March, when the amounts per bud (and concentrations of starch and total soluble protein) rose sharply, coinciding with an increase in the size of buds. Sucrose did not occur at detectable levels. Conference buds contained significantly higher concentrations of fructose and free amino acids than Comice. The implications for understanding bullfinches' bud-feeding habits are discussed.

Do Contrastingly Colored Unripe Fruits of the Neotropical Tree Ardisia nigropunctata Attract Avian Seed Dispersers?

“…Furthermore, staggered fruit ripening may benefit the plant since birds will eat only a few ripe fruits at once, preventing frugivore satiation at one particular time and potentially increasing the dispersal (Fuentes 1995). Sequential color change may also encourage birds to consume more per visit because ripe fruits are unlikely to be decayed, whereas fruits of all the same color could be of distinct ages (Grieg-Smith et al 1983). Finally unripe fruit color may actually serve as warning coloration, for example of repellent chemicals, to deter birds from taking unripe fruits (Janzen 1983).…”

Review of bird repellents

“…Other sources of repellents include screening natural products (Greig-Smith et al 1983;Crocker and Perry 1990;Reichardt 1997) and food and flavor ingredients (Mason and Clark 1992). However, there is no guarantee that such compounds are intrinsically safer from an environmental or toxicological perspective (Secoy and Smith 1983).…”

Plant chemistry and bird repellents

“…Fruit growers have long been aware that Bullfinches Pyrrhula pyrrhula prefer Conference pear buds to Comice buds, even though there are only small differences in their food values (Summers and Jones 1976, Greig-Smith et al 1983. Greig-Smith (1985) applied extracts of these buds to hemp seeds and filmed Bullfinches eating them.…”