\[ **BT: [[birds]]** ] --- # *Calidris pugnax* (ruffs) The ruff is a medium-sized wading bird that breeds in marshes and wet meadows across northern Eurasia. This highly gregarious sandpiper is migratory and sometimes forms huge flocks in its winter grounds, which include southern and western Europe, Africa, southern Asia and Australia.[^1] [[Ruffs are ‘highly sexually dimorphic’.]][^2] [[The nesting behaviour of Ruffs is, generally, solitary; however, several females may lay their eggs close to the same lek.]][^3] ## population demographics ### sex ratio [[Ruffs often show a pronounced inequality in the numbers of each sex. A study of juveniles in Finland found that only 34% were males and 1% were faeders.]][^4] [[Female ruffs, when in poor condition, appear to produce a larger proportion of males at the egg stage. When females are in better condition, any bias in the sex ratio is smaller or absent.|‘It appears that [female Ruffs] produce a larger proportion of males at the egg stage when they are in poor physical condition. When females are in better condition, any bias in the sex ratio is smaller or absent.’]][^4] ### three male morphs [[The ruff has three male forms—the independent, the satellite, and the faeder. Each form is associated with different behaviours which are maintained for life.]][^5] #### differences between forms ![[Küpper et al., ‘Supergene Determines Highly Divergent Male Reproductive Morphs in the Ruff’, 2016.#^f690e4]] ##### independent [[In ruffs, ‘Independents’ are the more aggressive male morph. They are highly territorial, with a breeding strategy focused on either residing in their own territory or invading the territory of a competing Independent.]][^6] ##### satellites [[‘Satellites’ are the semi-cooperative male ruff morph. Rather than seeking territory of their own, Satellites ‘couple’ submissively with an Independent already in possession of established territory.]][^7] ##### faeders [[‘Faeders’ are female mimics—i.e. their phenotype gives them a female appearance. However, Faeder testes are 2.5 times the size of other males (suggesting quality over frequency re. copulation).]][^7] [[Male ruffs of the ‘Faeder’ morph hide as females so effectively that they weren’t detected by human researchers prior to genetic testing.]][^7] [[‘Faeder’ ruff males are popular with both other males and females. Male–male copulations have been frequently observed between Faeder and Independent males. Interestingly, the Faeders are ‘on top’ as often as the Independents.]][^8] [[Some theorise that ‘Faeder’ ruff males are exhibiting a ‘sneaker’ breeding strategy; that is, mimicking females to slip past the radar of both Independent and Satellite males and mate with females while those bigger males are distracted.]][^9] [[David Lank hypothesized that ‘Faeder’ ruff males are not sneakers but, instead, mimic females to cuckold males by luring the males away from females and onto themselves.]][^10] #### evolution of the three forms [[The behaviour and appearance of each individual male ruff remain constant through its adult life. These differences in form are determined by a simple genetic polymorphism.]][^11] [[The strikingly different male morphs of the ruff (Philomachus pugnax) are determined by a supergene ‘consisting of divergent alternative, dominant and non-recombining haplotypes’.]][^12] [[Re. Ruff morphs, ‘scientists were able to show that the first genetic change happened 3.8 million years ago on the resident chromosome, when a part of it broke off and was reintroduced in the wrong direction. This inversion created the faeder allele.’]][^13] [[About 500,000 years ago, another rare recombination event led to the satellite allele (in ruffs).]][^14] [[Although it’s apparent that stable genetic polymorphs, such as the three male morphs seen in Calidris pugnax, must be associated with fitness (and maintained by selection), it isn’t really understood how such strategies form or why they’re so rare.]][^15] [[The evolution of the ruffs three male morphs does appear to reflect female choice.]][^7] [^1]: ‘Ruff (Bird)’, Wikipedia, last edited 18 December 2025, 18:11 (UTC), <https://en.wikipedia.org/wiki/Ruff_(bird)>. [^2]: Joop Jukema and Theunis Piersma, ‘[[Jukema and Piersma, ‘Permanent Female Mimics in a Lekking Shorebird’, 2006|Permanent Female Mimics in a Lekking Shorebird]]’, *Biology Letters*, vol. 2, no. 2 (2006), p. 161, [https://doi.org/10.1098/rsbl.2005.0416](https://doi.org/10.1098/rsbl.2005.0416). [^3]: ‘Ruff (Bird)’, Wikipedia, last edited 5 October 2025, 14:42 (UTC), <https://en.wikipedia.org/wiki/Ruff_(bird)>. [^4]: ‘Ruff (Bird)’, Wikipedia, last edited 6 October 2024, 20:02 (UTC), https://en.wikipedia.org/wiki/Ruff_(bird). [^5]: Clemens Küpper, et al. ‘[[Küpper et al., ‘Supergene Determines Highly Divergent Male Reproductive Morphs in the Ruff’, 2016.|A Supergene Determines Highly Divergent Male Reproductive Morphs in the Ruff]]’, *Nature Genetics*, vol. 48, no. 1 (2016), p. 79, [https://doi.org/10.1038/ng.3443](https://doi.org/10.1038/ng.3443); ‘Ruff (bird)’, Wikipedia, last edited 6 October 2024, https://en.wikipedia.org/wiki/Ruff_(bird); Joop Jukema and Theunis Piersma, ‘[[Jukema and Piersma, ‘Permanent Female Mimics in a Lekking Shorebird’, 2006|Permanent Female Mimics in a Lekking Shorebird]]’, *Biology Letters*, vol. 2, no. 2 (2006), p. 161, [https://doi.org/10.1098/rsbl.2005.0416](https://doi.org/10.1098/rsbl.2005.0416). [^6]: Clemens Küpper, et al. ‘[[Küpper et al., ‘Supergene Determines Highly Divergent Male Reproductive Morphs in the Ruff’, 2016.|A Supergene Determines Highly Divergent Male Reproductive Morphs in the Ruff]]’, *Nature Genetics*, vol. 48, no. 1 (2016), p. 79, [https://doi.org/10.1038/ng.3443](https://doi.org/10.1038/ng.3443); David B. Lank et al., ‘[[Lank et al., ‘Genetic Polymorphism for Alternative Mating Behaviour in Lekking Male Ruff Philomachus Pugnax’, 1995|Genetic Polymorphism for Alternative Mating Behaviour in Lekking Male Ruff Philomachus Pugnax]], *Nature*, vol. 378, no. 6552 (1995), p. 59, [https://doi.org/10.1038/378059a0](https://doi.org/10.1038/378059a0); Fredrik Widemo, ‘[[Widemo, ‘Natural History of the Ruff’, c. 1992.|Natural History of the Ruff]]’, Home Page of Dr. Frederik Widemo, \[c. 1992], accessed 3 March 2026, https://web.archive.org/web/20071031231507/http://www.ebc.uu.se/zooeko/FredrikW/Ruff.html; Joop Jukema and Theunis Piersma, ‘[[Jukema and Piersma, ‘Permanent Female Mimics in a Lekking Shorebird’, 2006|Permanent Female Mimics in a Lekking Shorebird]]’, *Biology Letters*, vol. 2, no. 2 (2006), p. 161, [https://doi.org/10.1098/rsbl.2005.0416](https://doi.org/10.1098/rsbl.2005.0416). [^7]: Joop Jukema and Theunis Piersma, ‘[[Jukema and Piersma, ‘Permanent Female Mimics in a Lekking Shorebird’, 2006|Permanent Female Mimics in a Lekking Shorebird]]’, *Biology Letters*, vol. 2, no. 2 (2006), p. 161, [https://doi.org/10.1098/rsbl.2005.0416](https://doi.org/10.1098/rsbl.2005.0416). [^8]: Joop Jukema and Theunis Piersma, ‘[[Jukema and Piersma, ‘Permanent Female Mimics in a Lekking Shorebird’, 2006|Permanent Female Mimics in a Lekking Shorebird]]’, *Biology Letters*, vol. 2, no. 2 (2006), pp. 162,163, [https://doi.org/10.1098/rsbl.2005.0416](https://doi.org/10.1098/rsbl.2005.0416); ‘[[Hooijmeijer et al., ‘Newsletter Ruff Research’, 2009|Newsletter Ruff Research 2009]]’, newsletter, with Jos Hooijmeijer et al., University of Groningen, 2009, pp. 13, 14, [https://cr-birding.org/sites/default/files/prattachment/Ruff%20%283553%29%20newsletter%202009.pdf](https://cr-birding.org/sites/default/files/prattachment/Ruff%20%283553%29%20newsletter%202009.pdf). [^9]: Joop Jukema and Theunis Piersma, ‘[[Jukema and Piersma, ‘Permanent Female Mimics in a Lekking Shorebird’, 2006|Permanent Female Mimics in a Lekking Shorebird]]’, *Biology Letters*, vol. 2, no. 2 (2006), pp. 161, 163, [https://doi.org/10.1098/rsbl.2005.0416](https://doi.org/10.1098/rsbl.2005.0416). [^10]: ‘[[Hooijmeijer et al., ‘Newsletter Ruff Research’, 2009|Newsletter Ruff Research 2009]]’, newsletter, with Jos Hooijmeijer et al., University of Groningen, 2009, p. 14, [https://cr-birding.org/sites/default/files/prattachment/Ruff%20%283553%29%20newsletter%202009.pdf](https://cr-birding.org/sites/default/files/prattachment/Ruff%20%283553%29%20newsletter%202009.pdf); Joop Jukema and Theunis Piersma, ‘[[Jukema and Piersma, ‘Permanent Female Mimics in a Lekking Shorebird’, 2006|Permanent Female Mimics in a Lekking Shorebird]]’, *Biology Letters*, vol. 2, no. 2 (2006), p. 161, [https://doi.org/10.1098/rsbl.2005.0416](https://doi.org/10.1098/rsbl.2005.0416). [^11]: ‘Ruff (bird)’, Wikipedia, last edited 6 October 2024, 20:02 (UTC), https://en.wikipedia.org/wiki/Ruff_(bird). [^12]: Clemens Küpper, et al. ‘[[Küpper et al., ‘Supergene Determines Highly Divergent Male Reproductive Morphs in the Ruff’, 2016.|A Supergene Determines Highly Divergent Male Reproductive Morphs in the Ruff]]’, *Nature Genetics*, vol. 48, no. 1 (2016), p. 79, [https://doi.org/10.1038/ng.3443](https://doi.org/10.1038/ng.3443). [^13]: ‘Ruff (Bird)’, Wikipedia, last edited 6 October 2024, 20:02 (UTC), https://en.wikipedia.org/wiki/Ruff_(bird). [^14]: ‘Ruff (Bird)’, Wikipedia, last edited 6 October 2024, 20:02 (UTC), https://en.wikipedia.org/wiki/Ruff_(bird). [^15]: Clemens Küpper, et al. ‘[[Küpper et al., ‘Supergene Determines Highly Divergent Male Reproductive Morphs in the Ruff’, 2016.|A Supergene Determines Highly Divergent Male Reproductive Morphs in the Ruff]]’, *Nature Genetics*, vol. 48, no. 1 (2016), p. 79, [https://doi.org/10.1038/ng.3443](https://doi.org/10.1038/ng.3443); David B. Lank et al., ‘[[Lank et al., ‘Genetic Polymorphism for Alternative Mating Behaviour in Lekking Male Ruff Philomachus Pugnax’, 1995|Genetic Polymorphism for Alternative Mating Behaviour in Lekking Male Ruff Philomachus Pugnax]], *Nature*, vol. 378, no. 6552 (1995), p. 62, [https://doi.org/10.1038/378059a0](https://doi.org/10.1038/378059a0).