Hilltopping (biology) explained

Hilltopping (also spelt hill-topping) is a mate-location behaviour seen in many insects including butterflies, dragonflies, bumblebees,^[1] wasps,^[2] beetles^[3] and flies.^[4]

Males of many butterfly species may be found flying up to and staying on a hilltop - for days on end if necessary. Females, desirous of mating, fly up the hill. Males dash around the top, competing for the best part of the area - usually the very top; as the male with the best territory at the top of the hill would have the best chance of mating with the occasional female, who knows the "top male" must be strong and thus genetically fit. Many authors consider this as a form of lekking behaviour.^[5] Many butterfly species including swallowtails, nymphalids, metal-marks and lycaenids are known to hill-top.

In some Acraea butterflies, widespread infection by Wolbachia results in a rarity of males and in these species the females widely engage in hilltopping behaviour.^[6] Female butterflies at hilltopping sites are predominantly of unmated individuals.^[7]

Studies have shown that even slight elevation differences on flat terrain can trigger hilltopping behaviour.^[8] Flowering or tall trees may induce hilltopping behaviour.^[9]

The concentrating effect of hilltopping on butterfly populations makes such locations of special conservation significance.^[10]

Notes and References

1. 10.1111/j.1365-2311.2011.01297.x. Evidence for hilltopping in bumblebees?. Ecological Entomology. 36. 5. 560. 2011. Goulson. Dave. Sangster. Elizabeth L.. Young. Jill C.. 2011EcoEn..36..560G . 84363729 .
2. Alcock, J. 1985. Hilltopping behaviour in the wasp Pseudomasaris maculifrons (Fox) (Hymenoptera: Masaridae). J. Kansas. Entomol. Soc. 58:162-166.
3. Schaedla, W. H. 2005. Hilltopping on termitaries by the Indochinese tiger beetle, Heptodonta analis (Cincindelidae). Insect Science 12(2):151
4. Alcock, J. 1989. The mating system of Mydas ventralis (Diptera: Mydidae). Psyche 96:167-176 http://psyche.entclub.org/96/96-167.html
5. Alcock, J. 1987. Leks and hilltopping in insects. J. Nat. Hist.21:319-328.
6. Jiggins, Francis M. 2002. Widespread ‘hilltopping’ in Acraea butterflies and the origin of sex-role-reversed swarming in Acraea encedon and A. encedana Afr. J. Ecol. 40:228-231
7. Shields, O. (1967) Hilltopping. J. Res. Lep. 6:69-178
8. Baughman, John F., Dennis D. Murphy 1988. What Constitutes a Hill to a Hilltopping Butterfly? American Midland Naturalist. 120(2):441-443 doi:10.2307/2426017
9. Journal of Research on the Lepidoptera . Scott . James A. . Mate-Locating Behavior of Western North American Butterfiles. II. New Observations and Morphological Adaptations . dead . https://web.archive.org/web/20180128074651/http://lepidopteraresearchfoundation.org/journals/21/PDF21/21-177.pdf . 2018-01-28 . 2023-12-01 .
10. New, T. R. 1993. Conservation Biology of Lycaenidae (butterflies). The World Conservation Union (IUCN)