|| 要旨トップ | 目次 |||日本生態学会第61回全国大会 (2014年3月、広島) 講演要旨
一般講演（ポスター発表） PA2-081 (Poster presentation)
Higgs boson is a particle that could explain where mass comes from. Without mass, particles just couldn’t hold together. In bird breeding colonies, hundreds of individuals nest close to one another during the breeding season. Seabirds form colonies on the same cliffs or islands for many years, and limitation of available breeding sites play the role of Higgs bosons for site fidelity. In contrast, heron colonies also exhibit site fidelity despite breeding sites, or trees or bamboo thickets, are pretty abundant. In Ibaraki Prefecture, 41 out of 61 colonies formed during 1963-2013 exhibited site fidelity by relocating to the same sites over many years or by remaining within small areas rather than moving far away. To find differences between colonies with and without site fidelity, we calculated the area of surrounding landuse (water, urban, forest and paddy field), frequency of vegetation loss and human disturbance, and repulsive/attractive force against each colony from surrounding colonies. Colonies with site fidelity were characterized by a low frequency of disturbance and strong attractive force. None of landuse factors contributed to site fidelity. Distributed colonies in previous years per se play the role of Higgs bosons for herons to form colonies in the next year.