Coloniality

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Coloniality
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Colonial breeding

• Definitionbreeding among densely distributed
  territories that contain no resource other than
  nest sites

Northern Gannet and Common Guillemot colony
(Image by Wikimedia Commons)
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Prevalence

• Some fish (e.g., stickleback), reptiles (marine
  iguana), mammals (most pinnipeds)
• 13 of all birds (Lack 1968)
• gt 95 of seabirds (Danchin and Wagner 1997)
• Colonial breeding is an evolutionary precursor to
  marine habitat in birds (Rolland et al. 1998)

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Nesting Australian Gannets, New Zealand. (Image
by Wikimedia Commons)
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Sea lion and elephant seal colony, San Clemente
Island, CA
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Sandwich Tern
Royal Tern
Sooty Tern
Black Skimmer
Brown Pelican
Tricolored Heron
Laughing Gull
Mixed-species breeding colony, Isles Dernieres,
Louisiana
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Outline

• Costs Benefits
• Explanations
• Functional approach
• Commodity selection approach
• Evidence for predation as mechanism for
  coloniality

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David Lack (1910-1973)

• Density dependence suggests that selective
  pressures should operate more strongly on
  populations at high densities.
• Coloniality is problematic in light of density
  dependence.
• Benefits to colonial breeding
  must outweigh costs.

Photo of David Lack http//www.todayinsci.com/L/L
ack_David/ Laysan Albatross colony, 1902 L.W.
Rothschild, Wikimedia Commons
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• Hypothetical relationships
• between density and fitness
• a) Allee effect
• b) aggregation benefit
• c) tradeoffs

Stokes and Boersma 2006
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Costs

• Competition (inter/intraspecific)
• Nest sites
• Mates
• Food?
• Disease and parasite transmission
• Cannibalism
• Adult aggression towards other chicks
  (inter/intraspecific)
• Energetic costs of travel to foraging location

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Benefits

• Feeding
• Information sharing
• Multi-species interactions in foraging groups,
  sharing info, partitioning resource, i.e.
  vertical depth of food (Camphyusen and Webb 1999)
• Cooperative feeding
• Patchy food resources
• Non-territorial

Black Skimmer by J. White Herring Gulls by S.
Youngren
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Benefits

• Predator defense
• Nesting synchrony
• Predator mobbing
• Vigilance many eyes
• Maximize limited breeding sites

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Wittenberger and Hunt 1985

• A wide variety of hypotheses has been advanced
  to explain avian coloniality, but none has been
  adequately tested, and little information is
  available for determining which hypotheses are
  most likely to apply to any given species.

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Functional approach

• Benefits lead to coloniality (ORIGIN)
• Predation
• Vigilance
• Swamping (breeding synchrony)
• Defense
• Food finding
• Information center
• Recruitment center

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Commodity Selection approach

• Benefits are byproducts of coloniality
  (MAINTENANCE)
• Spatial aggregation
• Traditional aggregation
• Reproductive success
• Sexual selection
• Kin selection/philopatry

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Predation and Coloniality

• Nest predation may be either reduced or
  increased by coloniality, leaving this question
  unresolved. (Varela et al. 2007)
• Colonies defend against predators?
• Colonies attract predators?
• Evidence for both!

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Evidence () (Anderson and Hodum 1993)

• Galapagos Hawks showed preferential predation of
  Blue-footed Booby nests that were most isolated
  from nearest neighbors

• Benefit of dense nesting

Blue-footed Booby by RJ Hall Galapagos Hawk by
M. Karatay, both from Wikimedia Commons
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Evidence (-)(Stokes and Boersma 2000)

• Fledging success of Magellenic Penguins declines
  with increasing density at both the local and
  area scale
• Predation and intraspecific
• aggression increase with
• colony density
• Cost of dense nesting

Guglielmo Celata, Wikimedia Commons
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Evidence () Murphy and Schauer 1996

• Common Murres breeding on cliffs had higher nest
  success with more breeding neighbors (i.e.,
  higher density)
• Ravens had nowhere to land if nests tightly
  packed
• Ravens attacked by
• neighbors if they did land
• Benefit of dense nesting

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Evidence (-)(Burger 1984)

• Large Least Tern colonies experienced
  significantly more predation than small colonies
• Predators may be attracted to large
  concentrations of prey
• Least Tern anti-predator
• behavior likely ineffective
• due to size
• Cost of dense nesting

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Does predation select for or against avian
coloniality? A comparative analysis(Varela et
al. 2007)

• Classified extant species as
• Colonial/Solitary
• Vulnerable/Protected
• Phylogenetic approach
• Does avian phylogeny support predictions of
  Reduced Predation Hypothesis or Increased
  Predation Hypothesis?

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Hypotheses (Varela et al.2007)

• Reduced Predation Hypothesis (RPH)
• Coloniality reduces predation risk- BENEFIT
• Increased Predation Hypothesis (IPH)
• Coloniality increases predation risk- COST

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Predictions (Varela et al.2007)

• Reduced Predation Hypothesis (RPH)
• Solitary/vulnerable ? Colonial
• - Solitary/protected ? Colonial
• Colonial/protected ? Vulnerable
• - Solitary/protected ? Colonial
• Increased Predation Hypothesis (IPH)
• Colonial/vulnerable ? Solitary
• - Colonial/protected ? Solitary
• Colonial/vulnerable ? Protected
• - Solitary/vulnerable ? Protected

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Predictions (Varela et al.2007)
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Vulnerability?

• 4 metrics of extant species
• Nest position
• Nest approachability
• Nest accessibility
• Nest type

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Phylogenetic approach

• Ciconiiformes highest incidence of coloniality
  within Aves
• 30 families, 363 species, 48 colonial
• Minimum evolutions/reversals
• Coloniality 23/8
• Nest position 11/14
• Nest approachability 19/30
• Nest accessibility 19/18
• Nest type 15/4

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RPH IPH
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RPH IPH
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RPH IPH
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RPH IPH
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Results

• Evolution of coloniality is significantly
  correlated with nest vulnerability
• Support for predictions of IPH, not for RPH
• Solitary ? Colonial is independent of nest
  Vulnerability
• Vulnerable ? Protected is more likely if Colonial
• Colonial ? Solitary is more likely if Vulnerable
• Protected ? Vulnerable is more likely if Solitary

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Conclusions

• Predation pressure does not contribute to the
  origin of coloniality
• Benefits of coloniality are secondary adaptations
  to high density breeding that probably contribute
  to the maintenance of coloniality

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Wittenberger and Hunt 1985

• A wide variety of hypotheses has been advanced
  to explain avian coloniality, but none has been
  adequately tested, and little information is
  available for determining which hypotheses are
  most likely to apply to any given species.

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Now what?

• Commodity selection hypothesis!
• Coloniality byproduct of individual selection
• - habitat
• - mates
• - reproductive
• success
• - etc.

This looks good!
But do we really want to nest with these dummies?
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Questions?
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References

• Anderson DJ, Hodum PJ. 1993. Predator Behavior
  Favors Clumped Nesting in an Oceanic Seabird.
  Ecology 74 2462-2464.
• Burger, J. 1984. Colony stability in Least Terns.
  Condor 86 61-67.
• Danchin E,Wagner RH. 1997. The evolution of
  coloniality the emergence of new perspectives.
  Trends in Ecology Evolution 12 342-347.
• Lack, D. 1968. Ecological Adaptations for
  Breeding in Birds. Chapman and Hall, London.
• Murphy EC, Schauer JH. 1996. Synchrony in
  egg-laying and reproductive success of
  neighboring common murres, Uria aalge. Behavioral
  Ecology and Sociobiology 39 245-258.
• Rolland C, Danchin E, de Fraipont M. 1998. The
  evolution of coloniality in birds in relation to
  food, habitat, predation, and life-history
  traits A comparative analysis. American
  Naturalist 151 514-529.
• Stokes DL, Boersma PD. 2000. Nesting density and
  reproductive success in a colonial seabird, the
  magellanic penguin. Ecology 81 2878-2891.
• Varela, SAM, Danchin E, Wagner RH. 2007. Does
  predation select for or against avian
  coloniality? A comparative analysis. Journal of
  Evolutionary Biology 20(4) 1490-1503.
• Wittenberger JF, Hunt GLJ. 1985. The adaptive
  significance of coloniality in birds. In Avian
  Biology (D.S. Farner, J.R. King, K.C. Parkes,
  eds), pp. 178. Academic Press, New York.

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• The potential complexity of density effects in
  colonial organisms is reflected in the range of
  results of field studies of seabirds, a group in
  which 98 of all species nest colonially.
• Among habitat-limited populations and large
  species in which cannibalism is a major cause of
  egg and chick loss, breeding success has been
  found to be negatively correlated with nesting
  density.
• For species in which habitat limitations are not
  severe and cannibalism is uncommon, high density
  generally results in higher success because of
  reduced predation rates, although increased
  density may also lead to higher predation rates,
  and some studies have found highest success at
  intermediate densities.
• (Stokes and Boersma 2000)

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• Herring gull and Great Black-backed Gull
  mixed-species colony
• Appledore Island, ME
• Burger 1983
• 4000 L. argentatus
• 2000 L. marinus
• L. marinus more aggressive towards invading other
  species
• L. argentatus more aggressive towards invading
  conspecifics
• Both species were more aggressive towards the
  smaller Herring Gull.
• Explanation likelihood of winning the
  interaction

• Drawn from data in Burger 1983
• From Ellis and Good 2006

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Herring gull and Great Black-backed Gull
mixed-species colony Appledore Island, ME B.
Ellis and Good 2006 3000 L. argentatus 3000 L.
marinus L. marinus more aggressive towards
conspecifics L. argentatus more aggressive
towards other species Larger Great Black-backed
Gulls always exhibit more aggression Explanation
bigger, more aggressive species.

• Drawn from data in Burger 1983
• From Ellis and Good 2006

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Reproductive success

• Herring gulls best near conspecifics
• GBBG best near other species
• (Ellis and Good 2006)

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Evidence () Addison et al. 2006

• What about predation on adults?
• Tufted Puffins alter behavior when predators
  (Bald Eagles and Peregrine Falcons) are present
• reduced activity
• synchronous flights
• Denser flocks dilute predation
• risk

Tufted Puffin by Sarah Youngren