Courtship and mating behavior in four Pachytroctidae species (Psocodea: ‘Psocoptera’: Troctomorpha: Nanopsocetae: Pachytroctidae)

Courtship and mating behavior were investigated in four species, representing three different genera, in the family Pachytroctidae. All exhibited a lengthy courtship in the male-above position followed by brief copulation in the female-above position with both facing in the same direction. This courtship behavior has not previously been observed in ‘Psocoptera’ and may be unique to Pachytroctidae. In three of the species in this study, the spermatophore remnant protruded from the tip of the male’s abdomen after copulation, and was immediately deposited on the surface of the experimental enclosure. Differences in courtship behavior of the two closely related and sympatric Tapinella species, described in this report, may represent reproductive isolating mechanisms. Under experimental conditions, we observed a male of each Tapinella species mount, court, and attempt to mate with a virgin female of the other species. In each case the female rejected the male and failed to mate. Implications relative to these behaviors are discussed. DOI links to videos are provided for easy access.

Tests of emigration in small mammals under experimental conditions

Holding animals in enclosures that block emigration causes demographic abnormalities called "fence effects." Experimenters have built exits that require animals to move through unfavorable conditions to leave enclosures. There are doubts about whether individuals that cross these challenging exits are true emigrants. We tested whether an exit that required house mice (Mus musculus) to swim through a water-filled trough was used only by mice triggered to emigrate from an experimental enclosure. Also, we examined the responses of mice to the availability of resources and the presence of conspecific adult animals in a small enclosure with an exit and in an enclosure made by joining two single enclosures. All mice left a barren enclosure within 12 h but no mice left during 7-day trials in a resource-rich enclosure during spring and summer. At the end of trials with repeated introduction of pairs of mice, about 85% of resident mice were the first mice added. Nearly all mice added later left the enclosure. A relatively constant number of mice became residents in small enclosures and about 2.3 times as many mice resided in double enclosures. Mice readily found and used exits when motivated to leave and did not accidentally pass through exits during routine exploration. Thus, mice that stayed in enclosures were not "fenced in" by the water-filled exit and exhibited residency as in nature. Tests of exits should give ecologists confidence that animals can display normal residency and emigration behaviors in experimental settings. The defense of resources by residents and the emigration of excess animals resulted in a consistent limit to the number of animals able to reside in enclosures.

The effects of endrin on Microtus and Peromyscus. II. Enclosed field populations

Effects of endrin on enclosed field populations of Microtus pennsylvanicus and Peromyscus maniculatus were investigated in two 2-acre enclosures near Saskatoon, Saskatchewan. After removal trapping and introduction of marked animals, population changes were assessed by live-trapping at 2-week intervals from June to September 1968. The experimental enclosure was sprayed with endrin at 8.0 oz per acre on July 14, 1968.Before endrin was applied Microtus were more abundant in the experimental enclosure than in the control enclosure. Endrin caused immediate and significant mortality in the experimental population. Microtus which survived the spray subsequently survived as well as their control counterparts. Recruits entering the experimental population during post-spray periods survived significantly better than young entering the more crowded control population. This survival, combined with active post-spray breeding, yielded a final experimental population which significantly exceeded the control.Peromyscus escaped readily from both enclosures. Losses from the experimental enclosure were significantly greater than from the control enclosure during both pre-spray and post-spray periods. The tendency for Peromyscus to leave the experimental enclosure in greater numbers is related to the paucity of suitable woodland habitat and to inferred competitive interference from the grassland species Microtus.Finally, a simple model is presented which demonstrates the several ramifications of a biocide stress on small mammal populations.

Some haematological data from an experimental colony of rabbits, Oryctolagus cuniculus (L)

An analysis of haematological data collected during a period of 22 months from a colony of Australian wild rabbits, Oryctolagus cuniculus (L.), living in a 1.7-acre experimental enclosure, is presented. Erythrocyte, leucocyte, and reticulocyte counts were made, and the level of haemoglobin was determined in 815 blood samples taken at regular monthly intervals. Differences between sexes, ages, and seasons were examined statistically for various blood values. Haemoglobin concentration and red blood cell counts fell when the rabbit population rose above approximately 50 per acre but there was not a statistically significant rise in the counts of reticulocytes. White blood cell counts rose during breeding fights and high population density.