Open Access
How to translate text using browser tools
1 April 2008 Dominance Relationships in Dark-Bellied Brent Geese Branta bernicla bernicla at Spring Staging Areas
Maud Poisbleau, Diane Desmonts, Hervé Fritz
Author Affiliations +
Abstract

Spring staging is an important period influencing reproductive success for migratory birds. During this period, female geese must accumulate reserves for subsequent migration, egg laying and incubation. They may increase feeding opportunities by being guarded by dominant males protecting a large feeding area and providing feeding time, and/or having themselves a high dominance status. Using paired adults of Dark-bellied Brent Geese Branta bernicla, we tested if males had higher dominance scores than females, if larger individuals had higher dominance scores than smaller ones and if dominance ranks of paired partners were correlated. Our results supported the first and third predictions while, once controlled by sex, body size was not correlated with adult dominance status.

Introduction

Social dominance relationships exist in most, if not all, gregarious animals, from insects (e.g. Tindo & Dejean 2000) to mammals (e.g. Barrette & Vandal 1986). Establishing a dominance hierarchy may limit the costs of interactions with conspecifics, through the reduction of aggressive interactions (Rowell 1974, Archer 1988). For most migratory wildfowl, social dominance organisation may play a particularly important role during the times of year when these birds are gregarious. Body condition of geese in winter and spring affects positively their subsequent migration, breeding success and dominance status during the next winter (see Ebbinge & Spaans 1995, Poisbleau et al. 2006b). During migratory stops at staging areas, female geese must accumulate reserves for subsequent egg laying and incubation. The dominance status of the pair during this pre-breeding period, through its influence on foraging efficiency, could thus be a main determinant of future reproductive performance (Lamprecht 1986a, Ebbinge & Spaans 1995). In addition, females may enhance feeding opportunities, optimise food storage and maximise reproductive success when guarded by males protecting a space around the feeding female (Teunissen et al. 1985, Spaans et al. 2007) and allowing for some extra feeding time. Nevertheless, if determinants and consequences of dominance status are now quite well explored in wintering groups of geese (see for examples Boyd 1953, Raveling 1970, Black & Owen 1989a, Kotrschal et al. 1993, Poisbleau et al. 2006b), it is less the case at spring staging areas (see Black et al. 2007).

Dark-bellied Brent Geese Branta bernicla bernicla leave their wintering areas in Britain and France during March and early April and travel from the Atlantic coast to the Taimyr Peninsula, Russia, for reproduction (Green et al. 2002). Spring-staging stops may be required in the Wadden Sea (Netherlands, Germany, and Denmark) and White Sea (North-west Russia) to accumulate and restore reserves in anticipation of migration and reproduction events (Ebbinge & Spaans 1995). As for other goose species, the best predictor of dominance status is family size (Lamprecht 1986a,b, Black & Owen 1989b, Gregoire & Ankney 1990, Loonen et al. 1999, Poisbleau et al. 2006b). However, as in the spring staging period Brent Goose parents chase away their juveniles, most of the pairs act as single pairs (Cramp & Simmons 1977, Lambeck 1990a,b, Boyd 2005). Therefore, this period allows control for social dominance status, independently of the number of juveniles. In addition, a good breeding success may be the result of a higher social dominance status during spring staging and not the cause of it, as is likely the case during winter (Poisbleau et al. 2006b). We here analysed some main factors potentially affecting social dominance status in Brent Goose pairs without goslings, during their spring staging on Terschelling Island in the Wadden Sea. In this context and in accordance with a previous study on wintering Brent Geese (Poisbleau et al. 2006b), we aimed at testing predictions in Brent Geese that (1) males have higher dominance scores than females, (2) within each sex separately, larger individuals have higher dominance scores than smaller ones and (3) dominance ranks of paired partners are correlated.

Methods

During spring staging on Terschelling Island, the Netherlands, we caught Brent Geese using a cannon net, in May 2002 and 2003. Each bird was marked individually with coded Darvic coloured leg-rings. We determined sex by cloacal examination. Juveniles (first-year) were distinguished from birds in adult plumage (second-year and older) by the white edges of the wing coverts. To minimise observer biases, the same observer measured tarsus and culmen lengths to the nearest 0.01 mm using an electronic calliper, and measured wing length to the nearest millimetre with a ruler.

We studied social interactions at the capture site in May 2003, while the geese were foraging on polder grassland. For a given marked adult, we considered any interaction with any opponent, marked or not. We defined an interaction as a direct confrontation between two birds, ranging from threats with lowered head and neck to active chases with flapping wings (Stahl et al. 2001). We considered an interaction as being won by an individual when opponent(s) turned and walked or ran away. The dominance score was defined as the percentage of interactions won by a focal bird divided by the total number of interactions in which this bird participated (Ens & Goss-Custard 1984, Lamprecht 1986b). We calculated a dominance score for each marked individual for which we had seen a minimum number of 26 interactions in order to obtain an error less than 10% for the estimated score (Poisbleau et al. 2006c), i.e. for 28 different paired adults. The most dominant bird may reach a dominance score near 100%, the most dominated bird may have a score near 0%.

Using only individuals who were adults when they were captured, we used the first principal component score from a principal component analysis (PC1) of the three morphological measurements as an index of a bird's structural size (Rising & Somers 1989). All dominance scores were arcsine-transformed and all data then satisfied assumptions required by parametric statistical tests (Sokal & Rohlf 1995). Effects of sex and body size on dominance score were analysed using covariance analysis ANCOVA. Because of the restricted sample size, we used non-parametric tests for within-pair comparisons: Wilcoxon paired test to compare average dominance scores between males and females, and Kendall's rank correlation to test for the covariation of dominance scores between mates. All statistical analyses were performed using SYSTAT 7.0 (Wilkinson 1997).

Results

The first principal component (PC1) established from all captured adults (n = 103) described a positive correlation in body size variables. Loadings were 0.880 for tarsus, 0.855 for culmen and 0.855 for wing. PC1 had an eigenvalue of 2.237 and explained 75% of the variance of all three morphological variables.

Neither the interaction between sex and body size, nor body size significantly influenced spring dominance score in the initial model (sex ×body size: F1,24 = 0.592, P = 0.449; body size: F1,25 = 1.754, P = 0.197). The only parameter significantly affecting dominance score was sex, males being more dominant than females (F1,26 = 11.501, P = 0.002; Fig. 1). However, as males are usually larger than females (F1,101 = 114.501, R2 = 0.531, P < 0.001 from the entire capture database), we separately tested for the effect of size within each sex. For neither sex, larger adults significantly dominated smaller ones (males: F1,15 = 3.539, P = 0.079; females: F1,9 = 0.001, P = 0.976; Fig. 1).

Within-pair comparisons confirmed that males had a higher dominance score than females during spring staging (n = 9 pairs, of which both partners were ringed and had a dominance score; Z = 2.547, P = 0.011). Male and female dominance scores of the same pair were significantly and positively correlated across pairs (τ = 0.611, P = 0.022, Fig. 2) whereas their body sizes were not correlated (τ = 0.111, P = 0.677).

Discussion

The dominance status of Brent Geese during spring staging was explored. Our results confirmed the wintering observations (Poisbleau et al. 2006b) that male Brent Geese had a higher dominance score than females both between and within pairs. In addition, as paired birds tended to have comparable dominance scores, we showed that dominance scores of both mates were not independent within a pair during spring staging. Different non-exclusive reasoning could explain these two results. (1) First, the ‘co-operative hypothesis’ (Lamprecht 1986b) proposes that if both partners cooperate against opponents, both will have a rather similar dominance status. We knew and observed that, during spring staging, paired female Brent Geese forage actively while males perform mate guarding by standing next to their female and preventing others from approaching her (Teunissen et al. 1985). Indeed, the increase in female body mass during spring and ultimately the subsequent reproductive success of the pair will partially depend on this male protection (Ebbinge & Spaans 1995). Thus, females intervened in a minority of fights while their mates were actively protecting them. However, females were also involved in aggressive interactions without the intervention of their mates when the latter were less attentive and/or occupied elsewhere (pers. obs.). Therefore, the cooperative hypothesis cannot explain the observed dominance score covariation between paired birds. (2) Second, if dominance was correlated to another parameter such as morphology or age, and if Brent Geese tended to pair with mates of similar size or age, we would expect the same relationships. Actual and previous investigations showed no size-assortative pairing in Brent Geese (Poisbleau et al. 2006a). Moreover, as the interaction between body size and sex was not significant and body size did not significantly affect dominance score within each sex, the impact of body size on dominance relationships was mainly due to the sexual dimorphism, as males were both more dominant and larger than females, as in numerous other studies (Cramp & Simmons 1977, Lamprecht 1986b). Nevertheless, as we have not been able to test the effect of age, we cannot reject the second hypothesis. (3) Finally, we could suppose that geese directly form dominance-assortative pairs; most dominant males pairing with most dominant females and viceversa. We cannot verify this hypothesis because this requires the assessment of dominance status of birds both before and after pairing. In conclusion, our results suggest that it is now necessary to quantify male dominance status and mate-guarding efficiency using a larger and longer database integrating data before and after pairing as well as age. According to the importance of body reserves for the migration, egg-laying and incubation (see Spaans et al. 2007), it could be now pertinent to verify that females of pairs with high social rank build up a larger amount of body reserves in spring than females lower in rank would. Ultimately, a further monitoring of the same pairs on the breeding and/or wintering areas would be essential to comprehend the implications of their spring dominance status for their subsequent breeding success.

Figure 1.

Dominance score (in percentage) of adult male and female Brent Geese during spring staging on Terschelling Island in 2003 in relation to body size (n = 28).

f01_135.eps

Figure 2.

Relationship between male and female dominance scores (in percentage) within Brent Goose pairs during spring 2003 (n = 9).

f02_135.eps

We are grateful to Gerard J.D.M. Müskens, Janien van der Greft, Barwolt S. Ebbinge, Jan Ellens and Harry Horn for their help with Brent Goose capture and sightings. The manuscript benefited greatly from critical comments by Matthieu Guillemain, Laurent Demongin, Georgina Strange and Marcel M. Lambrechts. We thank Julia Stahl and two anonymous referees for their substantive comments that improved the manuscript. The programme was funded by the CNRS, the Office National de la Chasse et de la Faune Sauvage and the EU “Coast Bird Diversity” program EVK2-2000-00612.

REFERENCES

1.

J. Archer 1988. The behavioural biology of aggression. Cambridge University Press, Cambridge, UK. Google Scholar

2.

C. Barrette & D. Vandal 1986. Social rank, dominance, antler size, and access to food in snow-bound wild Woodland Caribou. Behaviour 97: 118–146. Google Scholar

3.

J.M. Black & M. Owen 1989a. Agonistic behaviour in Barnacle Goose flocks: assessment, investment and reproductive success. Anim. Behav. 37: 199–209. Google Scholar

4.

J.M. Black & M. Owen 1989b. Parent-offspring relationships in wintering Barnacle Geese. Anim. Behav. 37: 187–198. Google Scholar

5.

J.M. Black , J. Prop & K. Larsson 2007. Wild goose dilemmas. Branta Press, Groningen. Google Scholar

6.

H. Boyd 1953. On encounters between wild White-fronted Geese in winter-flocks. Behaviour 5: 85–129. Google Scholar

7.

H. Boyd 2005. Brent Goose (Brant) Branta bernicla. In: J. Kear (ed) Bird Families of the World. Ducks, geese and swans. Oxford University Press, Oxford, pp. 321–329 Google Scholar

8.

S. Cramp & K.E.L. Simmons (eds) 1977. Handbook of the birds of Europe, the middle east and North Africa. Oxford University Press, Oxford. Google Scholar

9.

B.S. Ebbinge & B. Spaans 1995. The importance of body reserves accumulated in spring staging areas in the temperate zone for breeding in Dark-bellied Brent Geese Branta b. bernicla in the high Arctic. J. Avian Biol. 26: 105–113. Google Scholar

10.

B.J. Ens & J.D. Goss-Custard 1984. Interference among Oystercatchers, Haematopus ostralegus, feeding on Mussels, Mytilus edulis, on the Exe Estuary. J. Anim. Ecol. 53: 217–231. Google Scholar

11.

M. Green , T. Alerstam , P. Clausen , R. Drent & B.S. Ebbinge 2002. Dark-bellied Brent Geese Branta bernicla bernicla, as recorded by satellite telemetry, do not minimize flight distance during spring migration. Ibis 144: 106–121. Google Scholar

12.

P.E. Grégoire & C.D. Ankney 1990. Agonistic behavior and dominance relationships among Lesser Snow Geese during winter and spring migration. Auk 107: 550–560. Google Scholar

13.

K. Kotrschal , J. Hemetsberger & J. Dittami 1993. Food exploitation by a winter flock of Greylag Geese: behavioral dynamics, competition and social status. Behav. Ecol. Sociobiol. 33: 289–295. Google Scholar

14.

R.H.D. Lambeck 1990a. Differences in migratory pattern and habitat choice between social classes of the Brent Goose Branta b. bernicla. Ardea 78: 426–440. Google Scholar

15.

R.H.D. Lambeck 1990b. The applicability of age ratio and brood size counts in population dynamic studies of the Brent Goose Branta b. bernicla. Ardea 78: 414–425. Google Scholar

16.

J. Lamprecht 1986a. Social dominance and reproductive success in a goose flock (Anser indicus). Behaviour 97: 50–65. Google Scholar

17.

J. Lamprecht 1986b. Structure and causation of the dominance hierarchy in a flock of Bar-headed Geese (Anser indicus). Behaviour 96: 28–48. Google Scholar

18.

M.J.J.E. Loonen , L.W. Bruinzeel , J.M. Black & R.H. Drent 1999. The benefit of large broods in Barnacle Geese: a study using natural and experimental manipulations. J. Anim. Ecol. 68: 753–768. Google Scholar

19.

M. Poisbleau , H. Fritz , S. Dano & M.M. Lambrechts 2006a. Body measurements and hormonal withinpair covariation in wintering and spring staging Dark-bellied Brent Geese Branta bernicla bernicla. Ardea 94: 127–131. Google Scholar

20.

M. Poisbleau , H. Fritz , M. Valeix , P.-Y. Perroi , S. Dalloyau & M.M. Lambrechts 2006b. Social dominance correlates and family status in wintering Dark-bellied Brent Geese, Branta bernicla bernicla. Anim. Behav. 71: 1351–1358. Google Scholar

21.

M. Poisbleau , S. Jenouvrier & H. Fritz 2006c. Assessing the reliability of dominance scores for assigning individual ranks in a hierarchy. Anim. Behav. 72: 835–842. Google Scholar

22.

D.G. Raveling 1970. Dominance relationships and agonistic behavior of Canada Geese in winter. Behaviour 37: 291–319. Google Scholar

23.

J.D. Rising & K.M. Somers 1989. The measurement of overall body size in birds. Auk 106: 666–674. Google Scholar

24.

T.E. Rowell 1974. The concept of social dominance. Behav. Biol. 11: 131–154. Google Scholar

25.

R.R. Sokal & F.J. Rohlf 1995. Biometry. Third edition. Freeman and Co., New York. Google Scholar

26.

B. Spaans , K. van't Hoff , W. van der Veer & B.S. Ebbinge 2007. The significance of female body stores for egg laying and incubation in dark-bellied brent geese Branta bernicla bernicla. Ardea 95: 3–15. Google Scholar

27.

J. Stahl , P.H. Tolsma , M.J.J.E. Loonen & R.H. Drent 2001. Subordinates explore but dominants profit: resource competition in high Arctic Barnacle Goose flocks. Anim. Behav. 61: 257–264. Google Scholar

28.

W. Teunissen , B. Spaans & R. Drent 1985. Breeding success in Brent in relation to individual feeding opportunities during spring staging in the Wadden Sea. Ardea 73: 109–119. Google Scholar

29.

M. Tindo & A. Dejean 2000. Dominance hierarchy in colonies of Belonogaster juncea juncea (Vespidae, Polistinae). Insect. Soc. 47: 158–163. Google Scholar

30.

L. Wilkinson 1997. Systat 7.0, New statistics. SPSS Inc., Chicago. Google Scholar

Appendices

SAMENVATTING

Bij vogels die in groepen voorkomen, kan op de voedselgronden een sterke concurrentie om voedsel ontstaan. Dat is onder meer het geval bij plantenetende soorten zoals ganzen. Omdat ganzen een groot deel van het jaar paarsgewijs opereren, kunnen partners steun aan elkaar hebben om een gunstige plek in de groep te bemachtigen. Te verwachten is dat de meest dominante dieren toegang hebben tot het beste voedsel. Het percentage gevechten dat een individu wint (de dominantiescore), kan als maat dienen voor de rangorde binnen een groep. In de onderhavige Studie, uitgevoerd aan Zwartbuikrotganzen Branta bernicla op Terschelling, bleek dat mannetjes hoger scoorden qua dominantie dan vrouwtjes, en dat de dominantiescore van mannetjes gecorreleerd was aan die van hun partner. Tegen de verwachting in werd voor de seksen afzonderlijk geen verband gevonden tussen de dominantiescore en de grootte van het dier. (JS)

Maud Poisbleau, Diane Desmonts, and Hervé Fritz "Dominance Relationships in Dark-Bellied Brent Geese Branta bernicla bernicla at Spring Staging Areas," Ardea 96(1), 135-139, (1 April 2008). https://doi.org/10.5253/078.096.0117
Received: 22 November 2007; Accepted: 1 February 2008; Published: 1 April 2008
KEYWORDS
assortative pairing
body size
brent geese
dominance score
spring staging
Back to Top