reproductive success of house sparrows along an urban gradient
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Reproductive success of house sparrows along an urban gradient. Kate Vincent (BSG), Will Peach (RSPB), Jim Fowler (DMU) & Phil Grice (NE). Methodology Fieldwork Key results Summary of findings. Study City - Leicester. City in the middle of England Population approx 285, 000

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reproductive success of house sparrows along an urban gradient

Reproductive success of house sparrows along anurban gradient

Kate Vincent (BSG), Will Peach (RSPB), Jim Fowler (DMU) &

Phil Grice (NE)

slide2
Methodology
  • Fieldwork
  • Key results
  • Summary of findings
study city leicester
Study City - Leicester

City in the middle of England

Population approx 285, 000

10th largest city in England

methodology
Methodology
  • Productivity along urban gradient

(nest boxes; urban/suburban/rural)

  • Investigate diet and invertebrate abundance
  • Used local pollution data
fieldwork
Fieldwork
  • 9 study sites (nest boxes/surveys)
fieldwork7
Fieldwork
  • Nestboxes used = 100 [500+ chicks ringed]
  • Monthly foraging observations in 44 locations – to establish habitat use
fieldwork8
Fieldwork
  • Habitat mapping around used boxes
  • Aphid abundance in home ranges
  • Over-winter survival – colour-ringed adult birds
biometrics nesting success
Biometrics/Nesting success
  • Weight • Tarsus length
  • Fat score • Muscle score
  • Faecal samples (400+) • Colour ringing
foraging observations
Foraging Observations
  • Does foraging change across season/area type?
  • Initial visit recorded habitat type
  • Made monthly visits to 44 transects
  • Recorded no. of adults/juveniles and habitat
habitat mapping
Habitat Mapping
  • Compare habitat around all used boxes
  • Used 13 habitat category system
  • Took radius of 70m around each nest (80-100 gardens in suburbia)
aphid abundance
Aphid abundance
  • 0-50m & 50-100m from box
  • selected 20 shrubs, 20 trees, 15 veg, 30 flowers
  • scoring 0 to 3 (none to infested)
key results
Key Results
  • Productivity/nesting success
  • Diet of nestlings
  • Chick condition
diet composition 175 samples from 2001 2002 2003
Diet composition (175 samples from 2001, 2002 & 2003)

Thanks to Del Gruar for helping analyse samples

nestling diet
Nestling Diet
  • Spiders, Aphids, Diptera & Beetles = 80% of all remains
  • Beetles & Diptera prominent in April/May
  • Aphids most prominent in June
  • Ants most prominent in July/August
nestling diet16
Nestling Diet
  • Aphids - urban>suburban>rural broods
  • Diptera - rural>suburban>urban broods
  •  ants in broods that died
  •  plant material during July/August & in broods that died
productivity nesting success
Productivity/nesting success
  • No. fledged  late summer
  •  No. fledged in home ranges with  grass/deciduous shrubs/trees &  concrete.
  •  No. fledged from broods fed a plant-dominated diet
  • High rate of chick starvation in June/July
slide18

 = 70% : 14 day chick period    

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I

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 = 20% : 14 day chick period

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brood survival
Brood survival
  • Suburban nests = 75% (whole nest period)
  • Rural nests = 78%
  • All habitats BTO (2002) = 96.5%
  • Lack of food causing complete or partial brood failure
    • inadequate provision of food  poor quality habitat
    • provision of unsuitable food  nutritional deficiency/starvation
productivity
Productivity
  • Mean no. fledged per attempt
    • suburban = 1.98 BTO = 2.6
    • rural = 2.37 BTO = 2.9
  • Seasonal Productivity
    • 4.21 young per year (suburban)
    • 4.67 young per year (rural)
    • Oxford 1990s study = 5.68
  • productivity in this study is low due to high complete/partial brood failures
chick condition
Chick condition
  • chicks fed  beetle had higher body condition indices
  •  grass, deciduous shrubs & trees,  concrete =  brood biomass
    • invert availability is sensitive to the habitat quality around nest
  • NO2 levels =  brood mass at fledging
    •  post-fledging survival
    • fledging in  polluted areas = survival disadvantage
slide23

Relative abundance of aphids within 100m of nests during June and July 2003.

Aphid scores are grouped into four reflecting low (0) to high (3) relative abundance

summary
Summary
  • No. fledging & brood biomass  in home ranges with  grass/deciduous shrubs/trees
    • suggests invertebrate availability sensitive to habitat quality
  •  fledged from broods fed a plant-dominated diet
    • evidence linking vegetable dominated diet with complete brood failures
  •  chick starvation during June/July not been reported before
  •  NO2 levels = lower brood mass at fledging
conclusions
Conclusions
  • nestling survival rate & no. young fledging are low
  • links between;
    • poor habitat quality/insect availability/nestling diet/brood condition
  • indicates direct effect of food limitation during the breeding season
  • causing  productivity in suburbia
conclusions26
Conclusions
  •  productivity demographic mechanism causing decline
  • demographic model - test if productivity levels are low enough to cause declines
  • incorporated suburban & rural productivity levels and known survival rates (adult, first-year, post-fledge)
  • showed suburban productivity is low enough to cause 10% decline p.a
a big thankyou to
A BIG THANKYOU TO
  • RSPB, EN & DMU
  • Dr Will Peach & Dr Jim Fowler
  • Derek Gruar (RSPB)
  • Phil Grice (EN)
  • All RSPB research assistants
  • CJ Wildbird Foods (nestboxes)
  • Householders that have nestboxes
  • Denis Summers-Smith
  • Ken Goodrich & LROS
  • Leicester City Council
  • My website: www.katevincent.org
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