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

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.Keywords airborne LiDAR · ATM multi-spectral · blue tit · energy expenditure · great tit · habitat quality · habitat structure · parkland · reproductive success · urban birds

How to integrate remotely sensed data and biodiversity for ecosystem assessments at landscape scale

“…ALS data has been used to explain bird observations, but often birds have been counted during the study and the focused study areas have often been relatively small, varying from hectares to square kilometres (e.g. Hinsley et al 2008;Jones et al 2013), while in comparison, our focus area was some magnitudes wider in size. In Switzerland, a database of the Ornithological Institute and nationally available LiDAR were used to calculate horizontal and vertical structural heterogeneity, to model the occurrence of four bird species, including the three-toed woodpecker, in 1 km 2 grids for an area of 21,620 km 2 (Zellweger et al 2013).…”

Do Highly Modified Landscapes Favour Generalists at the Expense of Specialists? An Example using Woodland Birds

“…about 70% "non-oak") were working harder than the average for all birds measured in the wood (Figure 3b) (Hinsley et al, 2008).…”

“…Airborne LiDAR can describe vegetation structure at both high resolution (sub-metre) and at a landscape-scale (Lefsky et al, 2002;Lim et al, 2003;Vierling et al, 2008) and thus has particular value in ecological applications (Hill et al, 2004;Bradbury et al, 2005;Hinsley et al, 2006Hinsley et al, , 2008. LiDAR uses a laser range finder to measure the height of points beneath the flight-path of an aircraft.…”

“…The effects of such gaps on the adults themselves were investigated in two habitat types (large wood and park) by measuring the daily energy expenditure (DEE) of adults feeding large (10-11 days of age) nestlings (Hinsley et al, 2008). Adults foraging in patchy habitat waste time and energy simply crossing gaps to reach suitable foraging locations (Hinsley, 2000).…”

Operational implementation of a LiDAR inventory in Boreal Ontario

“…Over the past decade, improvements in global positioning systems (GPS), inertial navigation systems (INS), computer hardware, LiDAR processing software, and reduced acquisition costs have promoted many of these applications from research to operational status in several jurisdictions (Naesset 2004, Evans et al 2006, Stephens et al 2007). Examples include predictive hydrology modeling (Murphy et al 2008, Mandlburger et al 2009), road location optimization and construction (Akay et al 2004, Aruga et al 2005, White et al 2010, harvest block engineering (Chung et al 2004), habitat definition (Clawges et al 2008, Hinsley et al 2008, and timber quantification (Holmgren and Jonsson 2004, Naesset 2004, Parker and Evans 2007. Research conducted specifically in Ontario has focused on estimating forest inventory and biophysical variables for tolerant northern hardwoods (Lim et al 2001(Lim et al , 2002(Lim et al , 2003Todd et al 2003;Lim and Treitz 2004;Woods et al 2008), boreal mixedwoods (Thomas et al 2006(Thomas et al , 2008 and conifer plantations (Chasmer et al 2006).…”