That of Male Pheromones
Stoddart (1971) has shown that the young born in the first litter of the year are much more likely to survive until the following pheromone breeding season than young born in later litters.
Considering that secretory output is maximal at the time the first litter becomes independent, it is tempting to suggest that the weanlings are in command of a complex olfactory repertoire from a very early age and are able to seize the available individual range sites so effectively that later aspirants are prevented from settling. Studies are in progress to verify these pheromone suggestions.
From his careful developmental study of the scent glands of the short-tailed shrew (Blarina brevicauda Say) Pearson (1946) states that both lateral organs and the ventral organ are visible at an age of 5 days. In adult males the lateral organs are usually thicker (and more productive? ) than the ventral, while the reverse is usually true for females. The lateral organs of pregnant females are greatly reduced and are sometimes only visible histologically. Learn more at http://blogs.rediff.com/mpommett/2017/02/11/human-pheromones-alarm-substance/
They are slightly better developed during lactation and when the shrew is in estrus. During winter, and in an estrus, the organs are well developed with little size difference between males and females Pearson concludes that the organs are used in some social context, but was unable to investigate marking behavior or when the scent was set according to http://shieldsvmoakciurs.page.tl/Straight-With-Pheromones.htm
The relationship between scent organ productivity and the breeding season has now been demonstrated sufficiently frequently for there to be little doubt as to its validity. In all species of Dipodomys, except elephantinus Grinnel, margaritae Mer- riam and mitchelli Mearns, the mid-dorsal organ is maximally productive during the breeding season and comparatively quiescent during the non-breeding time. In each of the species studied in depth (Quay 1953: merriami Mearns, agilis Gambel, hear- manni Le Conte, deserti Stephens and ordi Woodhouse) a higher proportion of males than females was found to be secreting at all times of the year and the size (area) of the organ in females only rarely surpassed that of male pheromones.
Sebaceous gland organs occur in the ﬂanks of several species of cricetid and microtid rodents (Cricetus cricetus L., Mesocricetus auratus Waterhouse, Microtus xzmthognatus Leach, M. chrotorrhinus Miller, Neofiber alleni True, Chilotus and Lagurus). Eibl-Eibesfeldt (1953) reports that both sexes of Cﬁcetus cricetus possess ﬂank organs, the secretions of which are rubbed on the inner walls of the burrows and on the burrow entrances.
The bases of grass tussocks and ﬂat stones are also marked and the secretion may be so plentiful on the latter as to be quite visible. The position of the organs in this species appears to be well suited for its role in passive marking. Lipkow (1954) regards the position of the ﬂank organ in Mesocri— cetus aumtus as an adaptation to the hamster’s partially subterranean way of life. Regrettably, little is known about any specialized behaviors associated with the ﬂank organs in Microtus, Neoﬁber, Chilotus and Lagurus, but it is thought that these rodents transfer secretion in a passive manner.