North American birds that feed on flying insects are experiencing steep population declines, particularly long-distance migratory populations in the northern breeding range. We determine, for the first time, the level of migratory connectivity across the range of a songbird using direct tracking of individuals, and test whether declining northern populations have higher exposure to agricultural landscapes at their nonbreeding grounds in South America. We used light-level geolocators to track purple martins, Progne subis, originating from North American breeding populations, coast-to-coast (n ¼ 95 individuals). We show that breeding populations of the eastern subspecies, P. s. subis, that are separated by ca. 2000 km, nevertheless have almost completely overlapping non-breeding ranges in Brazil. Most (76%) P. s. subis overwintered in northern Brazil near the Amazon River, not in the agricultural landscape of southern Brazil. Individual non-breeding sites had an average of 91 per cent forest and only 4 per cent agricultural ground cover within a 50 km radius, and birds originating from declining northern breeding populations were not more exposed to agricultural landscapes than stable southern breeding populations. Our results show that differences in wintering location and habitat do not explain recent trends in breeding population declines in this species, and instead northern populations may be constrained in their ability to respond to climate change.

The butterfly fauna of lowland Northern California has exhibited a marked decline in recent years that previous studies have attributed in part to altered climatic conditions and changes in land use. Here, we ask if a shift in insecticide use towards neonicotinoids is associated with butterfly declines at four sites in the region that have been monitored for four decades. A negative association between butterfly populations and increasing neonicotinoid application is detectable while controlling for land use and other factors, and appears to be more severe for smaller-bodied species. These results suggest that neonicotinoids could influence non-target insect populations occurring in proximity to application locations, and highlights the need for mechanistic work to complement long-term observational data.

The distribution of the parasitic copepod, Salmincola californiensis, on two size-groups (fry, fork length 3.2–5.8 cm; juveniles, fork length 10.2–27.0) of the sockeye salmon, Oncorhynchus nerka, is described. The existence of preferred sites for both groups is established. The distribution on the smaller fish differs from that on the larger in that on the former the copepods are most abundant in the region of pectoral and pelvic fins, whereas on the latter they are by far most common in the branchial cavity. Macroscopic and microscopic mechanical damage to the fish tissues, resulting from the presence and activity of the copepod, comprises injuries to gills, skin, muscle, and even bone. The "burrowing phenomenon" (failure on the part of the copepod to cease excavation of a completed cavity of implantation, resulting in perforation of body wall and penetration of the viscera) is reported upon for the first time.

A description is given of the life cycle of Salmincola californiensis (Copepoda: Lernaeopodidae), studied by continuous observation of developing parasites and by intermittent examination of infected sockeye salmon (Oncorhynchus nerka). The cycle consists of six stages: copepodid (free-swimming), four chalimus stages (attached by second maxillae to frontal filament), and adult (attached by bulla). The copepodid settles on the fish and uncoils its frontal filament. Each successive chalimus stage reattaches the filament during moulting, but chalimus IV breaks off, searches for the site of final attachment, and excavates an implantation cavity for the bulla. The male cycle is similar but its chalimus IV is of shorter duration and soon moults into the male adult, actively searching for the female. Morphology of all stages is described in detail. Some comments are made on life cycles in Caligoida.

The morphology and the anatomy of the bulla, a unique attachment organ of the parasitic copepods belonging to Lernaeopodidae (Caligoida) is described. By their anatomy the bullae can be divided into three types, associated with three groups of fishes: freshwater teleosts, marine teleosts, and elasmobranchs. The evolution of Lernaeopodidae is briefly outlined. The authors point out that the type of the bulla appears independent of the phylogenetic position of the parasite but is related only to the type of the host. It is concluded that the bulla is more than an attachment organ and that it enters into physiological association with the tissues of the fish.