Effects of structural and functional habitat gaps on breeding woodland birds: working harder for less

Shelley A. Hinsley, Ross A. Hill, Paul E. Bellamy, Nancy M. Harrison, John R. Speakman, Andrew K. Wilson, Peter N. Ferns

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Abstract

The effects of habitat gaps on breeding success and parental daily energy expenditure (DEE) were investigated in great tits (Parus major) and blue tits (Cyanistes caeruleus) in urban parkland (Cardiff, UK) compared with birds in deciduous woodland (eastern England, UK). Tree canopy height, the percentage of gap in the canopy and the percentage of oak (in the wood only) within a 30 m radius of nest boxes were obtained from airborne remote-sensed data. Breeding success was monitored and parental DEE (great tits: both habitats; blue tits: park only) was measured using doubly labelled water in birds feeding young. In the park, mean (+/- SD) tree height (7.5 +/- 4.7 m) was less than in the wood (10.6 +/- 4.5 m), but the incidence of gaps (32.7 +/- 22.6%) was greater (9.2 +/- 14.7%). Great tits and blue tits both reared fewer young in the park and chick body mass was also reduced in park-reared great tits. Park great tits had a higher DEE (86.3 +/- 12.3 kJ day(-1)) than those in the wood (78.0 +/- 11.7 kJ day(-1)) and, because of smaller brood sizes, worked about 64% harder for each chick reared. Tits in the park with more than about 35% gap around their boxes had higher DEEs than the average for the habitat. In the wood, great tits with less oak around their boxes worked harder than average. Thus structural gaps, and functional gaps generated by variation in the quality of foraging habitat, increased the costs of rearing young.

Original languageEnglish
Pages (from-to)615-626
Number of pages12
JournalLandscape Ecology
Volume23
Issue number5
Early online date2 Apr 2008
DOIs
Publication statusPublished - May 2008

Keywords

  • airborne LiDAR
  • ATM multi-spectral
  • blue tit
  • energy expenditure
  • great tit
  • habitat quality
  • habitat structure
  • parkland
  • reproductive success
  • urban birds
  • tit parus-major
  • laser-scanning data
  • blue tits
  • energy-expenditure
  • environmental-conditions
  • parental effort
  • clutch size
  • forest fragmentation
  • nestling growth

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