Supporting information
Appendix S1 Breakdown of extra-pair paternity rates (EPP rate, i.e. extra-pair offspring divided by total number of offspring per brood), nearest neighbor distances
(NND) and number of neighbors (NN) per subpopulation and year. Values indicate means and, in parentheses, SD. N = number of broods with offspring surviving to
blood sampling.
2002
Subpopulation n
EPP rate
NND
NN
Bergli
Egelsee
2 0.200 (0.283)
269.7 (0)
0 (0)
Feldbach
2
0 (0)
83.2 (0) 1.0 (0)
Greifensee
14 0.612 (0.415) 64.5 (56.0) 4.6 (2.1)
Hopperen
Hüsli
6 0.436 (0.370) 112.7 (27.6) 1.5 (0.6)
Kämmoos
Lützelsee
8 0.375 (0.443) 86.9 (58.8) 2.1 (1.5)
Pfäffikersee 13 0.435 (0.458) 60.3 (31.7) 4.3 (1.7)
Sackried
Seeweidsee
Uerzikon
2
0 (0) 102.5 (1.2) 2.0 (0)
Werrikon
All
47 0.430 (0.423) 84.4 (60.4) 3.2 (2.1)
2003
n
1
2
4
13
1
3
5
14
12
EPP rate
0 (-)
0 (0)
0.375 (0.479)
0.295 (0.364)
0 (-)
0.083 (0.144)
0.280 (0.259)
0.395 (0.435)
0.517 (0.341)
NND
99.5 (-)
108.4 (0)
75.1 (26.3)
68.7 (56.1)
182.1 (-)
125.5 (0)
20.7 (14.1)
72.0 (53.3)
50.3 (26.0)
NN
1 (-)
1.0 (0)
1.3 (0.5)
4.1 (2.1)
0 (-)
1.0 (0)
2.0 (0)
4.7 (2.6)
5.3 (2.2)
2 0.375 (0.530) 173.4 (0)
0 (0)
57 0.342 (0.372) 72.5 (51.5) 3.6 (2.5)
2004
n
EPP rate
NND
4 0.150 (0.300) 132.2 (0)
4 0.300 (0.476) 176.6 (3.0)
1
0 (-) 135.1 (-)
8 0.456 (0.389) 35.2 (12.8)
NN
1.0 (0)
0 (0)
1.0 (-)
7.5 (0.9)
2005
n
EPP rate
3 0.222 (0.385)
2
0 (0)
9
1
5 0.450 (0.512) 87.0 (49.5)
10 0.302 (0.402) 35.5 (12.8)
2.0 (1.0)
5.8 (1.0)
2 0.250 (0.354)
54.8 (0) 3.5 (0.7)
3 0.167 (0.289)
82.3 (0)
2.0 (0)
37 0.317 (0.385) 75.6 (52.8) 3.95 (2.9)
13
5
1
3
3
NND
22.1 (0)
222.0 (0)
NN
1.0 (0)
0 (0)
0.750 (0.375) 37.9 (32.7) 7.8 (2.6)
0 (-)
211.9 (-)
0 (-)
0.394 (0.387) 64.8 (29.7) 2.4 (1.0)
0.520 (0.502) 48.7 (25.2) 3.8 (0.8)
0 (-) 144.2 (-) 1.0 (-)
0.111 (0.192)
33.1 (0) 2.0 (0)
0.411 (0.084) 58.4 (28.6) 2.0 (0)
40 0.418 (0.407) 64.1 (54.8) 3.4 (2.9)
2002-2005
n
8
10
7
44
1
10
5
40
40
1
3
7
5
181
EPP rate
0.158 (0.294)
0.160 (0.324)
0.214 (0.393)
0.518 (0.412)
0 (-)
0.287 (0.344)
0.280 (0.259)
0.398 (0.414)
0.437 (0.410)
0 (-)
0.111 (0.192)
0.248 (0.239)
0.250 (0.354)
0.371 (0.396)
Appendix S2 List of papers being supportive or non-supportive of the density hypothesis.
Supportive
Bjornstad G, Lifjeld JT (1997) High frequency of extra-pair paternity in a dense and
synchronous population of Willow warblers Phylloscopus trochilus. Journal of Avian
Biology, 28, 319-324.
Charmantier A, Perret P (2004) Manipulation of nest-box density affects extra-pair paternity
in a population of blue tits (Parus caeruleus). Behavioral Ecology and Sociobiology,
56, 360-365.
Estep LK, Mays H, Keyser AJ, Ballentine B, Hill GE (2005) Effects of breeding density and
plumage coloration on mate guarding and cuckoldry in blue grosbeaks (Passerina
caerulea). Canadian Journal of Zoology-Revue Canadienne De Zoologie, 83, 11431148.
Gibbs HL, Weatherhead PJ, Boag PT, et al. (1990) Realized reproductive success of
polygynous Red-Winged Blackbirds revealed by DNA markers. Science, 250, 13941397.
Gowaty PA, Bridges WC (1991) Nestbox availability affects extra-pair fertilizations and
conspecific nest parasitism in Eastern Bluebirds, Sialia sialis. Animal Behaviour, 41,
661-675.
Gray EM (1996) Female control of offspring paternity in a western population of red-winged
blackbirds (Agelaius phoeniceus). Behavioral Ecology and Sociobiology, 38, 267278.
Hasselquist D, Bensch S, Vonschantz T (1995) Low frequency of extrapair paternity in the
polygynous Great Reed Warbler, Acrocephalus arundinaceus. Behavioral Ecology, 6,
27-38.
Hoi H, Hoi-Leitner M (1997) An alternative route to coloniality in the bearded tit: females
pursue extra-pair fertilizations. Behavioral Ecology, 8, 113-119.
Krokene C, Lifjeld JT (2000) Variation in the frequency of extra-pair paternity in birds: a
comparison of an island and a mainland population of blue tits. Behaviour, 137, 13171330.
Langefors A, Hasselquist D, von Schantz T (1998) Extra-pair fertilizations in the sedge
warbler. Journal of Avian Biology, 29, 134-144.
Lindstedt ER, Oh KP, Badyaev AV (2007) Ecological, social, and genetic contingency of
extrapair behavior in a socially monogamous bird. Journal of Avian Biology, 38, 214223.
Moller AP (1991) Density-dependent extra-pair copulations in the swallow Hirundo rustica.
Ethology, 87, 316-329.
Moller AP, Ninni P (1998) Sperm competition and sexual selection: a meta-analysis of
paternity studies of birds. Behavioral Ecology and Sociobiology, 43, 345 - 358.
Richardson DS, Burke T (1999) Extra-pair paternity in relation to male age in Bullock's
orioles. Molecular Ecology, 8, 2115-2126.
Ryder TB, Fleischer RC, Shriver WG, Marra PP (2012) The ecological–evolutionary
interplay: density-dependent sexual selection in a migratory songbird. Ecology and
Evolution, 2, 976-987.
Stewart SLM, Westneat DF, Ritchison G (2010) Extra-pair paternity in eastern bluebirds:
effects of manipulated density and natural patterns of breeding synchrony. Behavioral
Ecology and Sociobiology, 64, 463-473.
Westneat DF, Sherman PW (1997) Density and extra-pair fertilizations in birds: a
comparative analysis. Behavioral Ecology and Sociobiology, 41, 205-215.
Yezerinac SM, Gibbs HL, Briskie JV, Whittam R, Montgomerie R (1999) Extrapair paternity
in a far northern population of yellow warblers Dendroica petechia. Journal of Avian
Biology, 30, 234-237.
Non-supportive
Ardern SL, Ma W, Ewen JG, Armstrong DP, Lambert DM (1997) Social and sexual
monogamy in translocated New Zealand robin populations detected using
minisatellite DNA. Auk, 114, 120-126.
Barber CA, Robertson RJ, Boag PT (1996) The high frequency of extra pair paternity in tree
swallows is not an artifact of nestboxes. Behavioral Ecology and Sociobiology, 38,
425-430.
Bollinger EK, Gavin TA (1991) Patterns of extra-pair fertilizations in Bobolinks. Behavioral
Ecology and Sociobiology, 29, 1-7.
Bouwman KM, Komdeur J (2006) Weather conditions affect levels of extra-pair paternity in
the reed bunting Emberiza schoeniclus. Journal of Avian Biology, 37, 238-244.
Charmantier A, Blondel J (2003) A contrast in extra-pair paternity levels on mainland and
island populations of mediterranean blue tits. Ethology, 109, 351-363.
Casey, AE, Sandercock BK, Wisely, SM (2011) Genetic parentage and local population
structure in the socially monogamous upland sandpiper. Condor, 113, 119-128.
Chuang HC, Webster MS, Holmes RT (1999) Extrapair paternity and local synchrony in the
Black-throated Blue Warbler. Auk, 116, 726-736.
Dunn PO, Robertson RJ, Michaud-Freeman D, Boag PT (1994a) Extra-pair paternity in tree
swallows: why do females mate with more than one male? Behavioral Ecology and
Sociobiology, 35, 273-281.
Dunn PO, Whittingham LA, Lifjeld JT, Robertson RJ, Boag PT (1994b) Effects of breeding
density, synchrony, and experience on extrapair paternity in tree swallows.
Behavioral Ecology, 5, 123-129.
Griffith SC, Stewart IRK, Dawson DA, Owens IPF, Burke T (1999) Contrasting levels of
extra-pair paternity in mainland and island populations of the house sparrow (Passer
domesticus): is there an 'island effect'? Biological Journal of the Linnean Society, 68,
303-316.
Gullberg A, Tegelstrom H, Gelter HP (1992) DNA fingerprinting reveals multiple paternity
in families of Great and Blue Tits (Parus major and Parus caeruleus). Hereditas, 117,
103-108.
Gyllensten UB, Jakobsson S, Temrin H (1990) No evidence for illegitimate young in
monogamous and polygynous warblers. Nature, 343, 168-170.
Hill GE, Montgomerie R, Roeder C, Boag P (1994) Sexual selection and cuckoldry in a
monogamous songbird: implications for sexual selection theory. Behavioral Ecology
and Sociobiology, 35, 193-199.
Johannessen LE, Slagsvold T, Hansen BT, Lifjeld JT (2005) Manipulation of male quality in
wild tits: effects on paternity loss. Behavioral Ecology, 16, 747-754.
Korpimaki E, Lahti K, May CA, et al. (1996) Copulatory behaviour and paternity determined
by DNA fingerprinting in kestrels: Effects of cyclic food abundance. Animal
Behaviour, 51, 945-955.
Leisler B, Beier J, Staudter H, Wink M (2000) Variation in extra-pair paternity in the
polygynous great reed warbler (Acrocephalus arundinaceus). Journal für
Ornithologie, 141, 77-84.
Moore OR, Stutchbury BJM, Quinn JS (1999) Extrapair mating system of an asynchronously
breeding tropical songbird: the mangrove swallow. Auk, 116, 1039-1046.
Moore JA., Kamarainen AM, Scribner KT, Mykut C, Prince HH (2012) The effects of
anthropogenic alteration of nesting habitat on rates of extra-pair fertilization and
intraspecific brood parasitism in Canada geese Branta canadensis. Ibis, 154, 354-362.
Stutchbury BJM, Quinn JS (1999) Extrapair mating system of an asynchronously breeding
tropical songbird: the mangrove swallow. Auk, 116, 1039-1046.
Olsen BJ, Greenberg R, Fleischer RC, Walters JR (2008) Extrapair paternity in the swamp
sparrow, Melospiza georgiana: male access or female preference? Behavioral
Ecology and Sociobiology, 63,285-294.
Orell M, Rytkonen S, Launonen V, et al. (1997) Low frequency extra-pair paternity in the
willow tit Parus montanus as revealed by DNA fingerprinting. Ibis, 139, 562-566.
Rätti O, Lundberg A, Tegelstrom H, Alatalo RV (2001) No evidence for effects of breeding
density and male removal on extrapair paternity in the pied flycatcher. Auk, 118, 147155.
Reyer HU, Bollmann K, Schlapfer AR, Schymainda A, Klecack G (1997) Ecological
determinants of extrapair fertilizations and egg dumping in Alpine water pipits
(Anthus spinoletta). Behavioral Ecology, 8, 534-543.
Rowe KMC, Weatherhead PJ (2007) Social and ecological factors affecting paternity
allocation in American robins with overlapping broods. Behavioral Ecology and
Sociobiology, 61, 1283-1291.
Sundberg J, Dixon A (1996) Old, colourful male yellowhammers, Emberiza citrinella,
benefit from extra-pair copulations. Animal Behaviour, 52, 113-122.
Tarof SA, Stuchbury BJ, Piper WH, Fleischer RC (1998) Does breeding density covary with
extra-pair fertilizations in hooded warblers? Journal of Avian Biology, 29, 145-154.
Thusius KJ, Dunn PO, Peterson KA, Whittingham LA (2001) Extrapair paternity is
influenced by breeding synchrony and density in the common yellowthroat.
Behavioral Ecology, 12, 633-639.
Vaclav R, Hoi H (2002) Importance of colony size and breeding synchrony on behaviour,
reproductive success and paternity in house sparrows Passer domesticus. Folia
Zoologica, 51, 35-48.
Westneat DF, Mays HL (2005) Tests of spatial and temporal factors influencing extra-pair
paternity in red-winged blackbirds. Molecular Ecology, 14, 2155-2167.