Diet of harbor porpoises along the Dutch coast: A combined stable isotope and stomach contents approach

High stranding frequency of porpoises, Phocoena phocoena, along the Dutch coast since 2006 has led to increased interest in the ecology of porpoises in the North Sea. Stranded porpoises were collected along the Dutch coast (2006–2008) and their diet was assessed through stomach content and stable isotope analysis (δ¹³C and δ¹⁵N) of porpoise muscle and prey. Stable isotope analysis (SIAR) was used to estimate the contribution of prey species to the porpoises' diet. This was compared to prey composition from stomach contents, to analyze differences between long‐ and short‐term diet. According to stomach contents, 90.5% of the diet consisted of gobies, whiting, lesser sandeel, herring, cod, and sprat. Stable isotope analysis revealed that 70‐83% of the diet consisted of poor cod, mackerel, greater sandeel, lesser sandeel, sprat, and gobies, highlighting a higher importance of pelagic, schooling species in the porpoises' diet compared to stomach contents. This could be due to prey distribution as well as differences in behavior of porpoises and prey between the coastal zone and offshore waters. This study supports the need for multi‐method approaches. Future ecological and fishery impact assessment studies and management decisions for porpoise conservation should acknowledge this difference between the long‐ and short‐term diet.     

Group characteristics,site fidelity,and photo‐identification of harbor porpoises,Phocoena phocoena,in Burrows Pass,Fidalgo Island,Washington

Little is known about harbor porpoises at the individual level or local group structure. Group characteristics, site fidelity, and photo‐identification of harbor porpoises were investigated off Fidalgo Island, Washington State. Harbor porpoise presence was affected by season and rip tide strength (Wald χ² P < 0.04); calf presence was influenced by season and tide (Wald χ² P < 0.0075). Average group size (2.32 ± 1.38, n = 266) was influenced by season, behavior, and calf presence (F₇ = 9.71, P < 0.0001, R² = 0.294). Fifty‐three individuals were identified using a matrix of primary, secondary, and confirmation markings that were stable over months/years. Over 35% were resighted in more than 1 mo (range 1–7, = 1.83); 15.1% were seen in more than 1 yr, suggesting some level of residency. Despite having higher effort, presence and group size were significantly lower in Summer. Variations in the significance of rip tide strength and tides relate to calf presence and support other findings that harbor porpoise population structure is complex and varies at small spatiotemporal scales and may also vary between populations and habitats. This study identifies variables affecting group characteristics and emphasizes the importance of research on local populations of harbor porpoises.     

New insights into the northward migration route of gray whales between Vancouver Island,British Columbia,and southeastern Alaska

The route taken by northward migrating gray whales during spring between Vancouver Island and southeastern Alaska, a distance of about 575 km, has long been uncertain. It is generally believed that the whales closely follow the western, outer coastline of Haida Gwaii (formerly the Queen Charlotte Islands), an archipelago lying between Vancouver Island and southeastern Alaska, consistent with their pattern of migrating close to shore over the majority of their northward migratory corridor. By tracking satellite‐tagged individuals and surveying whales from shore bases, we provide evidence that this is not the primary migratory corridor, but instead that most whales migrate through Hecate Strait and Dixon Entrance, broad waterways that lie to the east and north of Haida Gwaii. By using this route, northbound gray whales potentially face a wider range of industrial activities and developments than they would by migrating along the outer coast.     

Factors driving the variability in diving and movement behavior of migrating humpback whales (Megaptera novaeangliae): Implications for anthropogenic disturbance studies

Humpback whales (Megaptera novaeangliae) undertake one of the longest migrations of any animal and while on a broad‐scale this journey appears direct, on a fine‐scale, behaviors associated with socializing and breeding are regularly observed. However, little is known about which social and environmental factors influence behavior during this time. Here we examined the effect of multiple factors on the movement (speed and course) and diving behavior (dive and surfacing duration) of humpback whales during migration off the eastern coast of Australia. Focal data (202 h) were collected on 94 different whale groups with simultaneous social and environmental context data. The environmental factors water depth and wind speed were found to be important predictors of dive and movement behavior, whereas social factors were less influential at this site. Groups tended to dive for longer with increased water depth but traveled more slowly in increasing wind speeds. These baseline studies are crucial when examining the effect of anthropogenic disturbance. Determining which natural factors significantly affect behavior ensures any observed behavioral changes are correctly attributed to the disturbance and are not a result of other factors. In addition, any responses observed can be put into biological context and their relative magnitude determined.     

Making it through the first year: Ontogeny of movement and diving behavior in harbor seals from Svalbard,Norway

Phocid seal pups must learn successful survival strategies, largely independently, following their abrupt weaning at a relatively young age. To explore the ontogeny of aquatic skills, space use and first‐year habitat choices made by harbor seals, pups (n = 30) were instrumented with satellite relay data loggers (SRDLs) in Svalbard, Norway in 2009 and 2010. Initially, the pups had small home ranges and showed rapid changes in their activity budgets and diving capabilities, displaying steep linear increases in diving depth and duration and in the amount of time spent diving. Most pups underwent an abrupt shift in movement patterns at ca. 50 d of age, which likely marked the end of the postweaning fast. Around this same time, the steep progression in diving performance slowed, though longer, deeper dives gradually became the norm. However, bottom time, ascent and descent rates, and postdive recovery times remained stable after the postweaning fast, suggesting that most aquatic skill acquisition was completed during the first months of life. Few clear effects of environmental variables such as upwelling phenomenon, which are known to influence the diving behavior of adults from the same population, were detected in the diving patterns of pups.     

A comparison of image and observer based aerial surveys of narwhal

From 25 to 30 August 2014 a double‐observer line‐transect survey was conducted over Melville Bay, home to one of two summering populations of narwhal (Monodon monoceros) off West Greenland. A total of 1,932 linear kilometers was surveyed along 33 transects. In addition to using observers, the aircraft was equipped with two oblique cameras to capture a comparable data set. Analysts reviewed the images for narwhal sightings, which were then matched to the observer sightings. The objectives of the study were to determine advantages and disadvantages of the detection capabilities of both methodologies, and to conduct a comparative analysis of population abundance estimates. Correcting for the truncated detection distance of the images (500 m), the image analysts recorded more sightings (62) and a lower mean group size (2.2) compared to aerial observers (36 and 3.5, respectively), resulting in comparable numbers of individuals detected by both platforms (135 vs. 126). The abundance estimate based on the image sightings was 2,536 (CV = 0.51, 95% CI: 1,003–6,406), which was not significantly different from the aerial observers estimate of 2,596 individuals (CV = 0.51; 95% CI: 961–7,008). This study supports the potential of using UAS for marine mammal abundance studies.     

Toxicity,behavior impairment,and repellence of essential oils from pepper‐rosmarin and patchouli to termites

Plant essential oils are potential sources of insecticidal compounds, but have rarely been explored for their effect on termites. In the present study, we assessed the chemical composition of essential oils of Lippia sidoides Cham. (pepper‐rosmarin; Verbenaceae) and Pogostemon cablin (Blanco) Benth. (patchouli; Lamiacaeae) and evaluated their toxicity, behavioral impairment, and repellence to termite species of the genera Amitermes and Microcerotermes (Isoptera: Termitidae: Termitinae). The main components of essential oils of L. sidoides and P. cablin were thymol (44.6%) and patchouli alcohol (36.6%), respectively. The essential oil of P. cablin was most potent against Amitermes cf. amifer Silvestri and had the lowest LD₅₀ (0.63 μg mg^?1). There was no difference in toxicity for Microcerotermes indistinctus Mathews between the essential oils of L. sidoides (LD₅₀ = 1.49 μg mg^?1) and P. cablin (LD₅₀ = 1.67 μg mg^?1). Pogostemon cablin essential oil was the most toxic to M. indistinctus (LC₅₀ = 0.32 μl ml^?1) and A. cf. amifer (LC₅₀ = 0.29 μl ml^?1). The essential oils analyzed exhibited high toxicity and repellence to the termites, in addition to reducing behavioral interactions among individuals, thus constituting potential termiticides.     

“Show me which parasites you carry and I will tell you what you eat”, or how to infer the trophic behavior of hematophagous arthropods feeding on wildlife

Most emerging infectious diseases are zoonoses originating from wildlife among which vector‐borne diseases constitute a major risk for global human health. Understanding the transmission routes of mosquito‐borne pathogens in wildlife crucially depends on recording mosquito blood‐feeding patterns. During an extensive longitudinal survey to study sylvatic anophelines in two wildlife reserves in Gabon, we collected 2,415 mosquitoes of which only 0.3% were blood‐fed. The molecular analysis of the blood meals contained in guts indicated that all the engorged mosquitoes fed on wild ungulates. This direct approach gave only limited insights into the trophic behavior of the captured mosquitoes. Therefore, we developed a complementary indirect approach that exploits the occurrence of natural infections by host‐specific haemosporidian parasites to infer Anopheles trophic behavior. This method showed that 74 infected individuals carried parasites of great apes (58%), ungulates (30%), rodents (11%) and bats (1%). Accordingly, on the basis of haemosporidian host specificity, we could infer different feeding patterns. Some mosquito species had a restricted host range (An. nili only fed on rodents, whereas An. carnevalei, An. coustani, An. obscurus, and An. paludis only fed on wild ungulates). Other species had a wider host range (An. gabonensis could feed on rodents and wild ungulates, whereas An. moucheti and An. vinckei bit rodents, wild ungulates and great apes). An. marshallii was the species with the largest host range (rodents, wild ungulates, great apes, and bats). The indirect method substantially increased the information that could be extracted from the sample by providing details about host‐feeding patterns of all the mosquito species collected (both fed and unfed). Molecular sequences of hematophagous arthropods and their parasites will be increasingly available in the future; exploitation of such data with the approach we propose here should provide key insights into the feeding patterns of vectors and the ecology of vector‐borne diseases.     

Tag retention,wound healing,and subsequent reproductive history of southern right whales following satellite‐tagging

This paper presents data from 48 resightings of 16 southern right whales that were satellite‐tagged on the South African coast in September 2001, up to and including 2012. Tag performance in terms of number of days with locations received was significantly higher in males than females, and lowest in cows with calves, and attributed to behavioral differences leading to variable degrees of antenna damage. Resightings occurred from 4 to 4,054 d after tagging: tags were retained in all whales seen within 27 mo, but were apparently shed in all but one individual seen within 36 mo of tagging. The exception was a whale that still had the tag present 11 yr after tagging. Healing at the tag site occurred gradually and within 5 yr of tagging (and 2 yr after tag shedding). No significant difference in the subsequent frequency of calving was detected between 12 tagged and 382 untagged females photographed contemporaneously, and although statistical power was low, a 21% or greater reduction in calving rate in tagged females would seem incompatible with the observations. The death of one female 3 yr after tagging was more likely attributable to a ship strike on an animal debilitated by a prolapsed uterus.     

Characterization of postdive recovery using sound recordings and its relationship to dive duration,exertion, and foraging effort of southern elephant seals (Mirounga leonina)

It is notoriously difficult to measure physiological parameters in cryptic free‐ranging marine mammals. However, it is critical to understand how marine mammals manage their energy expenditure and their diving behavior in environments where the predation risks are low and where survival is mainly linked to capacities to maintain physiological homeostasis and energy budget balance. Elephant seals are top marine predators that dive deeply and continuously when at sea. Using acoustic recorders deployed on two postbreeding southern elephant seals (SES) females, we developed methods to automatically estimate breathing frequency at the surface. Using this method, we found that seals took successive identical breaths at high frequency (0.29 Hz) when recovering at the surface and that breath count was strongly related to postdive surfacing time. In addition, dive depth was the main factor explaining surfacing time through the effects of dive duration and total underwater swimming effort exerted. Finally, we found that recovery does not only occur over one dive timescale, but over a multidive time scale for one individual. The way these predators manage their recovery will determine how they respond to the change in oceanic water column structure in the future.     

Home‐ranges,population densities,vocal behavior,and post‐fledging movements of Cipo Canasteros (Asthenes luizae,Furnariidae), a rock‐specialist endemic of the highlands of eastern Brazil

Cipo Canasteros (Asthenes luizae, Furnariidae) have a fragmented and limited range restricted to the campos rupestres (rupestrian grasslands) habitat in the Brazilian highlands of the Espinhaço Range, and little is known about their behavior, ecology, and population biology. From March 2009 to November 2010, we monitored birds (24 banded and 22 radio‐tracked) at two study sites at Serra do Cipó in the state of Minas Gerais, Brazil, to estimate their home‐range sizes and population density, and describe their habitat use, natal dispersal behavior, and vocal behavior. We found an average density of 8.7 paired adults/km² in our study areas or 22.9 paired adults/km² when considering only used habitats. The sex ratio was male‐biased (males/total adults = 0.68), adults exhibited high site fidelity, home‐ranges averaged 4.0 ha (fixed kernel 95%) or 3.5 ha (95% minimum convex polygon) in size, and both sexes defended territories year‐round. We recorded four main types of songs, including two uttered more often during the breeding season. We monitored the natal dispersal of two males and one female who moved maximum distances of 1238 m, 780 m, and 1056 m, respectively, from natal areas. Our results confirm that Cipo Canasteros are restricted to the rocky‐outcrop habitat of the campos rupestres. In part due to their habitat specialization, Cipo Canasteros are considered Near Threatened, but other factors contributing to their demographic fragility include the small number, and probably low survival, of females and low reproductive success due to predation and brood parasitism by cowbirds. Given these threats, along with their specialized habitat and restricted range, the future conservation of Cipo Canasteros will likely depend on the extent to which their campos rupestres habitat can be conserved.     

Spatial and temporal patterns in the calling behavior of beluga whales,Delphinapterus leucas,in Cook Inlet,Alaska

Cook Inlet beluga whales (CIBs) are an endangered population residing in Cook Inlet, Alaska. We characterized the calling behavior of CIBs to improve our understanding of sounds produced by this population. Bottom‐moored hydrophones were deployed at Eagle Bay in summer 2009 and at Trading Bay in summer and winter 2009. CIB sounds were qualitatively analyzed and categorized as a whistle, pulsed call, or click train. A total of 4,097 calls were analyzed, and 66 unique whistle contours were identified. Whistles were quantitatively analyzed using a custom Matlab program. A chi‐square test showed the call category usage at Eagle Bay during summer 2009 and those at Trading Bay during summer 2009 and winter 2009–2010 differed significantly (P < 0.001). Pulsed calls were more common during summer months, and click trains within the frequency band (12.5 kHz) were more common in Eagle Bay. The variation in calling behavior suggests differences in habitat usage or in the surrounding environment, including background noise. With the proposed development projects in Cook Inlet and the potential increase in ambient noise level due to ocean acidification, it is important to understand how this endangered population uses sound, and what anthropogenic factors may influence that use.     

Variation of life‐history traits of the Asian corn borer,Ostrinia furnacalis in relation to temperature and geographical latitude

Life‐history traits from four geographical populations (tropical Ledong population [LD], subtropical Guangzhou [GZ] and Yongxiu populations, and temperate Langfang population [LF]) of the Asian corn borer, Ostrinia furnacalis were investigated at a wide range of temperatures (20–32°C). The larval and pupal times were significantly decreased with increasing rearing temperature, and growth rate was positively correlated with temperature. The relationship between body weight and rearing temperature in O. furnacalis did not follow the temperature–size rule (TSR); all populations exhibited the highest pupal and adult weights at high temperatures or intermediate temperatures. However, development time, growth rate, and body weight did not show a constant latitudinal gradient. Across all populations at each temperature, female were significantly bigger than males, showing a female‐biased sexual size dimorphism (SSD). Contrary to Rensch's rule, the SSD tended to increase with rising temperature. The subtropical GZ population exhibited the largest degree of dimorphism while the temperate LF exhibited the smallest. Male pupae lose significantly more weight at metamorphosis compared to females. The proportionate weight losses of different populations were significantly different. Adult longevity was significantly decreased with increasing temperature. Between sexes, all populations exhibit a rather female‐biased adult longevity. Finally, we discuss the adaptive significance of higher temperature‐inducing high body weight in the moth's life history and why the moth exhibits the reverse TSR.     

Summer diving and haul‐out behavior of leopard seals (Hydrurga leptonyx) near mesopredator breeding colonies at Livingston Island,Antarctic Peninsula

Leopard seals are conspicuous apex predators in Antarctic coastal ecosystems, yet their foraging ecology is poorly understood. Historically, the ecology of diving vertebrates has been studied using high‐resolution time‐depth records; however, to date such data have not been available for leopard seals. Twenty‐one time‐depth recorders were deployed on seasonally resident adult females in January and February between 2008 and 2014. The average deployment length was 13.65 ± 11.45 d and 40,308 postfilter dives were recorded on 229 foraging trips. Dive durations averaged 2.20 ± 1.23 min. Dives were shallow with 90.1% measuring 30 m or less, and a mean maximum dive depth of 16.60 ± 10.99 m. Four dive types were classified using a k‐means cluster analysis and compared with corresponding animal‐borne video data. Dive activity (number of dives/hour) was concentrated at night, including crepuscular periods. Haul‐out probabilities were highest near midday and were positively correlated with available daylight. Visual observations and comparisons of diving activity between and within years suggest individual‐based differences of foraging effort by time of day. Finally, dive and video data indicate that in addition to at‐surface hunting, benthic searching and facultative scavenging are important foraging strategies for leopard seals near coastal mesopredator breeding colonies.