The document summarizes a study on the territorial behaviors of blackbirds and their relationship to habitat features in Ravelston Woods, Edinburgh. The study found that blackbirds defended nesting sites as a limited resource, as shown by positive relationships between territorial activity and habitat features providing nesting sites like field layer cover and number of trees with ivy. In contrast, food resources like canopy cover showed no association with territoriality, since food was uniformly distributed and could be accessed outside of territories.

1. What does every blackbird stand for?
Researched by Anna Osicka
40086127@live.napier.ac.uk
Supervised by Patrick White
Acknowledgements
I would like to express my gratitude to Fraser Simpson for letting me to use his
beautiful drawing of a blackbird. For more please visit www.fssbirding.org.uk
Many thanks to Dr Patrick White for showing me the ropes in the marvellous
world of birds, and to Dr Rob Briers for helping me in crisis caused by
misbehaving residuals.
About the Project
Where: Ravelston Woods Local Nature Reserve, Edinburgh
When: 28 visits, from mid-February to mid-March
How:
• The area was surveyed and locations of territorial behaviours were
recorded.
• The site was divided into 20 m x 20 m sectors, habitat features were
recorded for each sector: canopy cover (%), leaf litter cover (%), field
layer cover (%), a number of trees with ivy.
Analysis:
• Territorial activity index was calculated.
• Regression analysis between the index and corresponding values of
habitat characteristics were performed.
References:
• Hatchwell, B.J., Chamberlain, D.E. and Perrins, C.M. (1993). The
reproductive success of Blackbirds Turdus merula in relation to habitat
structure and choice of nest site. Ibis. 138, 256–262.
• Snow, D.W. (1988). A Study of Blackbirds 2nd ed., London: British
Museum (Natural History).
Distribution of Habitat Features
• Food => uniformly distributed; nesting sites => clustered
• Canopy cover (left) => high coverage similar across the site; number of
trees with ivy (right) => more trees with ivy recorded on the eastern side of
the woods.
• Similar patterns recorded for leaf litter (uniformly) and field cover
(clustered)
Conclusions
• Lack of association between territoriality and habitat features relating to food => uniformly distributed, available from outside of territories => food was not
a limited resource.
• Positive relationships between territorial activity and habitat features providing nesting sites => not evenly distributed, nests always within a territory =>
nesting sites are a limited resource => provoke territorial behaviours.
• Future research: use of resources by blackbirds => for example nest use and success
Border
DO Not
ENTER!
0 20 40 60 80 10
0.0000.0020.0040.00
Canopy Cover (%
TerritorialActivity
0 20 40 60 80 100
0.0000.0020.0040.00
Leaf Litter Cover(
TerritorialActivity
0 20 40 60 80 100
0.0000.0020.0040.00
Field Cover(%)
TerritorialActivit
0 2 4 6 8 10
0.0000.0020.0040.0
Number of Trees
TerritorialActivitFood?
Nesting
Sites?
No association between
territoriality and canopy cover
A significant negative
relationship between territorial
activity and leaf litter cover
A significant positive
relationship between territorial
activity and field layer cover
A significant positive
relationship between territorial
activity and number of trees
with ivy
Sunflowerplots:eachred‘petal’representsamultipledatapoint.
Common ivy (Hedera helix)
Wild raspberry (Genus Rubus )
Territoriality
• Territoriality arises from competition for limited resources.
• Territorial behaviours are employed to defend boundaries.
• More resources => more competitors => more territorial behaviours
• Resources can be assessed by looking at habitat features (e.g. canopy)
The Blackbird
• Common blackbird (Turdus merula) is a territorial songbird.
• Territorial behaviours: singing, boundary displays, threatening body
postures, chasing and fights.
• Important resources:
• Food: invertebrates from leaf litter, caterpillars from canopy
• Nesting sites providing shelter from nest robbers: shrubs such
as brambles (‘field cover’), trees covered with ivy
• Expectations:
• Positive relationships between territorial activity and each of
the selected habitat features;
• Relationships for features providing nesting sites are stronger:
blackbirds feed often outside but nest always within territories.
What resources did blackbirds defend?