The effect of supplementary feeding in early spring on the breeding performance of the Great Spotted WoodpeckerDendrocopos major

Abstract

Capsule The provision of supplementary food in early spring led to an advance in laying date and increased productivity for the Great Spotted Woodpecker. Aims To use the experimental provision of supplementary food in the prebreeding period to investigate the role of food supply in determining laying date, subsequent synchrony with natural food availability and the impact on productivity for the Great Spotted Woodpecker. Methods Supplementary food in the form of fat blocks was provided at 13 feeding stations distributed over half of a 100-ha study wood from early February until late April 2011 with the other half of the wood left unfed. The breeding parameters (first egg date, clutch size, number of young fledged per nest and nest success) of Great Spotted Woodpeckers were monitored throughout the wood and data from the 'fed' and 'unfed' zones compared. The same breeding parameters collected throughout the wood in the five preceding years (2006-10) when there was no supplementary feeding were used to provide control data. The temporal pattern in the abundance of the main natural prey was monitored using caterpillar frass traps. Results In 2011, the mean first egg date for woodpecker nests in the fed zone of the wood was 4-5 days earlier than for those nests in the unfed zone. Nests in the fed zone were almost twice as productive as those in the unfed zone even though the supplementary feeding stopped before the main period of chick rearing. There were no differences in the breeding parameters in the two zones of the wood in the control years when there was no supplementary feeding. 2011 was a very warm spring and the natural prey abundance peaked very early so that none of the woodpeckers were well synchronized with their main breeding season prey. However, the small advancement in first egg date meant the supplemented birds were better synchronized than the controls. Conclusion The response of Great Spotted Woodpeckers to supplementary feeding suggests they may be limited in their ability to shift their breeding period to maintain synchrony with their natural prey in the breeding season. This has important implications for the response of the birds to warm springs which are expected to be more frequent under future climate change. Use of garden feeders by Great Spotted Woodpeckers has the potential to increase breeding success and may be one of the many factors contributing to their current population increase.

Food supplementation does not increase demographic rates in a passerine species of conservation concern

“…These results are consistent with 9/19 (47.4%) of published studies on fledging success in small passerines, which found no positive effect of food supplementation (Robb et al 2008). Although the provision of supplementary food resulted in increased brood size at fledging in great spotted woodpeckers (Dendrocopos major), it did not in great tits (Parus major), and brood size actually decreased in fed great and blue tits (P. caeruleus) in another study (Verboven et al 2001;Harrison et al 2010;Smith and Smith 2013).…”

Variation in timing of breeding of five woodpeckers in a primeval forest over 45 years: role of food, weather, and climate

“…Perrins (1965Perrins ( , 1970 suggested that this was because the laying females were delayed due to their inability to obtain adequate food. This postulate was confirmed in several food supplementation experiments, including food provisioning of Dendrocopos major in the pre-breeding period (Smith and Smith 2013), where the extra-fed birds did advance egg-laying (meta-analysis of Ruffino et al 2014). Therefore, 'food for females', the availability of food for egg-forming birds, could be more critical in shaping variation in breeding time than the synchronisation of the presence of young with the peak of their food availability.…”

Nest-site competition between bumblebees (Bombidae), social wasps (Vespidae) and cavity-nesting birds in Britain and the Western Palearctic

“…In Hertfordshire, Great Spotted Woodpecker nestcavities were monitored in 2011-14 from Hitch Wood Intensive searches of the Hertfordshire woods during April-June (Smith & Smith 2013) located 224 active nest-cavities of Great Spotted Woodpeckers (51-65 annually, 91% newly excavated that year), situated 2-25 m above the ground (mean = 11 m) in live (66%) and dead wood, mostly in oaks (51%) and Common Ashes (27%). Fifty-two unoccupied cavities were also inspected, which had been excavated by Great Spotted Woodpeckers in previous years.…”

“…Cavity dimensions were not recorded, but Great Spotted Woodpecker excavations are typically 25-35 cm deep, with a c. 49 mm diameter entrance (Kosinśki & Ksit 2007). Overall, 35% of active nest-cavities were found at or before the incubation stage and the remainder after hatching, and were inspected every few days using a miniature video camera to monitor progress (Smith & Smith 2013). Any incidences of bees or wasps in occupied or empty cavities were recorded.…”