The Role of the Navy in Future Warfare

The title of my talk today is the role of the Navy in future warfare. In such a discussion my inclination is to immediately thrust myself into the future since the history of the past, however glorious, is of little but academic interest to us unless it has definite application in the future

The Role of the Navy in Future Warfare

The title of my talk today is the role of the Navy in future warfare. In such a discussion my inclination is to immediately thrust myself into the future since the history of the past, however glorious, is of little but academic interest to us unless it has definite application in the future

The Heritage of Tyre

The first great seafaring people were apparently the Cretans or Minoans, but Phoenicia with her great port of Tyre was the first maritime nation of which we know the history

Between-Group Transmission Dynamics of the Swallow Bug, \u3ci\u3eOeciacus vicarius\u3c/i\u3e

The parasitic cimicid swallow bug, Oeciacus vicarius, is the principal invertebrate vector for Buggy Creek virus (BCRV) and has also been associated with Venezuelan equine encephalitis virus. To help understand the spread of this vector, we experimentally measured the transmission of O. vicarius between groups (colonies) of its main host, the cliff swallow (Petrochelidon pyrrhonota), in the field. Transmission of bugs between colonies varied significantly with year, size of the colony, and week within the season. Bug immigration into sites tended to peak in mid-summer. Swallow nests in larger colonies had more consistent rates of bug introduction than did nests in small colonies, but within a colony a given nest’s weekly immigrant-bug count varied widely across the season. Transmission of O. vicarius between host social groups follows broadly predictable seasonal patterns, but there is nevertheless temporal and spatial heterogeneity in bug transmission. By understanding how long-distance movement by this vector varies in time and space, we can better predict where and when BCRV epizootics may occur

Group Size and Ectoparasitism Affect Daily Survival Probability in a Colonial Bird

Little is known in general about how group size or ectoparasitism affect survival in colonial animals. We estimated daily within-season survival probabilities for nesting adult and recently fledged juvenile cliff swallows (Petrochelidon pyrrhonota) at 239 colonies from 1983 to 2003 in southwestern Nebraska, USA. Some colonies had been fumigated to remove ectoparasites. We conducted mark-recapture at each colony site to estimate daily survival. There were no systematic differences between males and females in daily survival. Adults and juveniles occupying parasite-free colonies had, on average, 4.4% and 62.2% greater daily survival, respectively, than their counterparts in naturally infested colonies. Daily survival of all birds increased with colony size for both parasite-free colonies and those under natural conditions, although the effect was stronger for adults at fumigated sites and for juveniles. Average daily survival probability for adults tended to increase during warmer and drier summers. Although daily survival varied at some sites over the course of the nesting cycle, there were no strongly consistent within-year temporal effects on survival. Even small differences in daily survival probability can translate into large effects on mean lifespan. The deleterious effects of ectoparasites on daily survival within the season represent a previously unknown cost of ectoparasitism. The increase in within-season survival with colony size reflects the net effects of many costs and benefits associated with colony size. Ectoparasitism is probably the most important cost that tends to partly balance the positive effects of large colonies. The greater survival of cliff swallows in the larger colonies is a previously unknown advantage of colonial nesting

Between-Group Transmission Dynamics of the Swallow Bug, \u3ci\u3eOeciacus vicarius\u3c/i\u3e

The parasitic cimicid swallow bug, Oeciacus vicarius, is the principal invertebrate vector for Buggy Creek virus (BCRV) and has also been associated with Venezuelan equine encephalitis virus. To help understand the spread of this vector, we experimentally measured the transmission of O. vicarius between groups (colonies) of its main host, the cliff swallow (Petrochelidon pyrrhonota), in the field. Transmission of bugs between colonies varied significantly with year, size of the colony, and week within the season. Bug immigration into sites tended to peak in mid-summer. Swallow nests in larger colonies had more consistent rates of bug introduction than did nests in small colonies, but within a colony a given nest’s weekly immigrant-bug count varied widely across the season. Transmission of O. vicarius between host social groups follows broadly predictable seasonal patterns, but there is nevertheless temporal and spatial heterogeneity in bug transmission. By understanding how long-distance movement by this vector varies in time and space, we can better predict where and when BCRV epizootics may occur

Ectoparasitism shortens the breeding season in a colonial bird

When blood-feeding parasites increase seasonally, their deleterious effects may prevent some host species, especially those living in large groups where parasites are numerous, from reproducing later in the summer. Yet the role of parasites in regulating the length of a host’s breeding season—and thus the host’s opportunity for multiple brooding—has not been systematically investigated. The highly colonial cliff swallow (Petrochelidon pyrrhonota), a temperate-latitude migratory songbird in the western Great Plains, USA, typically has a relatively short (eight to nine week) breeding season, with birds rarely nesting late in the summer. Colonies at which ectoparasitic swallow bugs (Oeciacus vicarius) were experimentally removed by fumigation were over 45 times more likely to have birds undertake a second round of nesting than were colonies exposed to parasites. Late nesting approximately doubled the length of the breeding season, with some birds raising two broods. Over a 27 year period the percentage of birds engaging in late nesting each year increased at a colony site where parasites were removed annually. This trend could not be explained by changes in group size, climate or nesting phenology during the study. The results suggest that ectoparasitism shortens the cliff swallow’s breeding season and probably prevents many individuals from multiple brooding. When this constraint is removed, selection may rapidly favour late nesting

\u3ci\u3eTerrapene ornata\u3c/i\u3e (Ornate Box Turtle) Predation on Cliff Swallows

During a 25-year study of Cliff Swallows (Petrochelidon pyrrhonota) in southwestern Nebraska, we observed Terrapene ornata prey, or attempt to prey, on swallows. On one occasion as large numbers of birds flushed and hit the net, the weight of the birds pulled the net down to ground level. One T. ornata, which was seen regularly at the colony, approached one adult Cliff Swallow that was very low in the net and killed it by biting and eating its head. After killing the bird, the turtle walked away carrying the head

\u3ci\u3eLithobates catesbeianus\u3c/i\u3e (American Bullfrog) Predation on Cliff Swallows

During a 25-year study of Cliff Swallows (Petrochelidon pyrrhonota) in southwestern Nebraska, we observed Lithobates catesbeianus prey on, or attempt to prey on, Cliff Swallows. As we were mist-netting Cliff Swallows at a 10-nest colony on 7 July 1998, a L. catesbeianus attempted to eat a Cliff Swallow that was caught in the net

Testis Size Increases with Colony Size in Cliff Swallows

By using a sample of more than 800 male cliff swallows (Petrochelidon pyrrhonota) that died during a rare climatic event in our Nebraska study area in 1996, we investigated how testis size was related to body size, age, parasite load, a bird’s past colony-size history, and spleen size. Testis volume in-creased with body size. After correcting for body size, testis volume was lowest for birds age 1 and 2 years but did not vary with age for males 3 years old or more. Birds occupying parasite-free (fumigated) colonies had significantly larger testes than did birds at non-fumigated sites. Testis volume increased significantly with the size of the breeding colonies a bird had used in the past. Testis vol-ume had no relationship with spleen volume after correcting for body size. The results show within a species that larger testes are favored in more social environments, probably reflecting a response to increased rates of extrapair copulation (and thus sperm competition) among cliff swallows in large colonies. The presence of ectoparasites, by inflating levels of plasma corticosterone, may in turn reduce testis mass. These data provide no support for the hypothesis that large testes, perhaps by pro-ducing more testosterone, are immunosuppressive and thus costly for that reason