This study made at Dumfries, SW Scotland, has revealed new information on the ecology and social structure of an urban colony of Lesser Black-backed and Herring Gulls Larus fuscus and L. argentatus. There has been a decline in the numbers of gulls nesting in Dumfries, contrary to a national trend of increasing numbers. These gulls nested socially and almost invariably had another pair within 100 m. Recruitment was almost totally confined to existing groups and new breeding areas were initiated by forming roosting groups on suitable sites. High-density groups were formed on flat roofs, usually on industrial and commercial properties, while low densities pairs occurred in residential areas and these pairs usually nested on chimneystacks. From 2000 to 2007, the public subjected nesting gulls to appreciable and increasing non-lethal disruption, mainly by nest and egg removal. This halved the overall breeding success and resulted in increased movement of nesting sites between years. However at sites not subjected to management, breeding success was high and movement was significantly lower. On low-density sites, nest-removal and proofing against nesting gulls mainly resulted in pairs moving a short distance, and did not reduce the numbers nesting in the immediate area. In contrast, synchronous removal of nests and eggs (or the prevention of breeding by netting or demolition) at high-density nesting sites caused desertion of the site. In the next breeding season, most of these displaced gulls failed to nest nearby, resulting in an appreciable reduction in density of gulls nesting in the immediate area. Further, the gulls did not move as a group elsewhere within the town. It is believed than many either failed to breed in the year after disruption or permanently emigrated from the town, an interpretation that is supported by two other studies. Surprisingly, few of the gulls that had their eggs and nest removed re-laid in that breeding season. These findings should be used to form the basis of non-lethal management of urban nesting gulls, which should be planned on an experimental basis to confirm and quantify the results from Dumfries.

Southern Illinois mined lands were investigated to identify wetland-scale habitat parameters influencing the presence of a habitat limited species, the Least Bittern (Ixobrychus exilis). Total area (ha), open water area (ha), robust emergent (REM) area (ha), percent REM coverage, REM-open water edge length (m), edge:REM cover index and water depth parameters were measured at 35 wetlands (mean = 5.51 ha; range = 0.13–39.7 ha) to develop one- and two-regressor logistic regression models best explaining Least Bittern wetland use. Logistic regression models using open-water area or open-water area edge index regressors ranked highest among candidate models, which distinguished our results from those obtained in previous studies. These data suggest that human-created basins supporting at least semi-permanently flooded robust emergent cover, ample expanses (>8 ha) of open water and high emergent edge lengths relative to flooded REM area may consistently meet breeding season requisites of Least Bitterns. Further work to validate or refine this profile of Least Bittern habitat may benefit efforts to enhance pre-existing wetland resources or create new ones.

Over an 18-month period regular counts were made of the water birds inhabiting lakes and ponds in the Lanín National Park in Argentinean Patagonia. A total of 130 bird surveys were conducted on 21 wetland areas, detecting 6,364 individuals belonging to 27 species from nine families. The most abundant and frequent species were Cloephaga poliocephala, Anas flavirostris, Fulica armillata and Fulica. leucoptera. Species richness was higher in spring and summer than in autumn and winter, involving 31 and 27 expected species, respectively. In contrast, bird abundance did not differ between season. The presence and abundance of bird species with respect to the surface area of the water body highlights the importance of certain lakes in particular. Thus, small water bodies (<100 ha) support higher numbers of birds; an average of 78.4–45.0 individuals as compared with larger lakes with an average of 18.58 birds. However, some species such as Phalacrocorax olivaceus, Podiceps major, Tachyeres patachonicus and Anas specularis were observed more at larger lakes, such differences being statistically significant. In contrast, Anas flavirostris, A. platalea and A. sibilatrix were more common in small and medium-sized lagoons. This information contributes to the development of management guidelines for the conservation of Patagonian wetlands.

Ground-based censuses of shorebirds were conducted during the winters of 2000–2008 (even years only) and the springs of 2002–2004 and 2008 at Estero Santa Cruz, Sonora, México, a 3,622 ha coastal wetland at the Gulf of California between the Colorado River Delta and Bahía Santa Maria and Ensenada Pabellones, Sinaloa. We documented 21 shorebird species using Estero Santa Cruz. Winter species richness averaged 13 (SD = 2, range 11–16 species, N = 8) while the spring species richness averaged eleven (SD = 2, range 8–16 species, N = 15). In all censuses, Calidris spp.—primarily Western Sandpiper (C. mauri)—was the most abundant species group, accounting for up to 92% of daily abundance—varying between 60–91% in winter and 34–92% in spring. The highest winter daily count of calidrids was 3,485 while the spring high count was 7,095. The two highest single day counts were the latest dates censused (10 April 2004, 9 April 2008) suggesting that the peak of spring migration comes later, and thus that peak shorebird abundance in the estero is higher than our censuses have recorded. Estero Santa Cruz and other estuaries geographically intermediate between larger shorebird staging areas and migratory bottlenecks represent important migratory stopover sites. Such sites allow for flexibility in migratory pathways, and thus deserve conservation attention and management.

Between April and July 2007 we surveyed the coasts of Jalisco, Colima, Michoacán and Guerrero, in southwestern Mexico. We documented 33 breeding localities of seven species of Charadriiformes: six of Snowy Plover, two of Collared Plover, five of Wilson's Plover, three of Killdeer, one of Gull-billed Tern, and 16 of the Least Tern. We also located a potential colony of the Black Skimmer. Twenty of these locations were documented for the first time. Excepting breeding localities of the Killdeer and three-four of the Least Tern, all colonies were on salt-flats, likely due to the sand dunes bordering beaches being narrow, well vegetated and used heavily by humans, or, for Snowy Plovers, perhaps owing to greater food availability on saltflats. Our data elevated the conservation value of Laguna Cuyutlán, Colima, and discovered the value of the Xola-Paramán system, in Jalisco, and Laguna El Potosí system and La Parota, in Guerrero.

Nest and chick census data gathered from 1975–2005 at all known breeding colonies of Royal (Sterna maxima) and Sandwich (S. sandivicensis) Terns in three mid-Atlantic States are reported. Nest census data were gathered sporadically in North Carolina, Virginia, and Maryland throughout this period. Royal Tern chick counts based on annual banding efforts were obtained in Maryland since 1975 and North Carolina and Virginia since 1977, while Sandwich Tern chick counts date from 1977 in North Carolina and 1980 in Virginia. Royal Tern chick counts show significant annual variation by state, and are positively correlated between North Carolina and Virginia, but negatively correlated between Maryland and both North Carolina and Virginia. Sandwich Tern nest counts showed significant annual variation in North Carolina, as did chick counts in North Carolina and Virginia. These results suggest regional, rather than local, trends in Royal Tern numbers over time. While Royal Tern numbers indicate a gradual decline in nests and chick production since the 1980s, followed by an increase in recent years, Sandwich Tern numbers have remained consistently lower than Royal Terns but stable over the entire study period. Causes for the decline in Royal Tern numbers are attributed primarily to loss of open sandy habitat from vegetational succession at breeding sites on dredged material islands and to invasive species at nesting sites, including quadraped predators. Increased habitat management and regular censusing with consistent methodology are recommended to help maintain these species at sustainable levels.

The Atlantic Coast population of Piping Plovers (Charadrius melodus) has been the focus of rangewide monitoring and recovery efforts since it was listed as Threatened in 1986 pursuant to the U.S. Endangered Species Act. Breeding pairs in the U.S. and Eastern Canada were censused annually from 1986 through 2006, and productivity (chicks fledged per breeding pair) was reported annually for varying proportions of the population. Census totals more than doubled, from 790 pairs in 1986 to 1,749 pairs in 2006, concomitant with sustained intensive management. Population growth was greatest and most rapid in the New England and New York-New Jersey recovery units, while increases were more modest in the Southern and Eastern Canada units. Periodic rapid declines in the Southern and Eastern Canada units raise concerns about long-term risks of extirpation. The Atlantic Coast population became less evenly distributed between 1989 and 2006, with the percentage of the population breeding in New England increasing from 21.5% to 36.2% while declining proportionately in the other three recovery units. Overall productivity for the Atlantic Coast population 1989–2006 was 1.35 chicks fledged per pair (annual range = 1.16–1.54), and overall productivity within recovery units decreased with decreasing latitude: Eastern Canada = 1.61, New England = 1.44, New York-New Jersey = 1.18, and Southern = 1.19. Within recovery units, annual productivity was variable and showed no sustained trends. There were significant, positive relationships between productivity and population growth in the subsequent year for each of the three U.S. recovery units, but not for Eastern Canada. There was a latitudinal trend in predictions of annual productivity needed to support stationary populations (λ = 1.0) within recovery units, increasing from 0.93 chicks fledged per pair in the Southern unit to 1.44 in Eastern Canada. These results are consistent with the hypothesis that survival rates of Atlantic Coast Piping Plovers decline with increasing latitude of breeding sites, and suggest that modified productivity objectives that are specific to individual recovery units may be appropriate.

The Least Bittern (Ixobrychus exilis) is a threatened species in Canada under the Species at Risk Act and breeds in manmade impoundments on Department of National Defence land in Nicolet/Baie-du-Febvre, Québec, a designated Migratory Bird Sanctuary. We conducted Least Bittern call-broadcast surveys in three adjacent basins in these impoundments from 2004 to 2006. Least Bittern abundance greatly fluctuated between these years with a maximum of 37 individuals in 2004, 16 in 2005, and increasing to 32 individuals in 2006, translating into 38, 18 and 31 estimated breeding pairs. A breach in a dyke occurred on the larger basin in the fall of 2004 where most Least Bitterns were detected, which decreased the water level of the marsh and altered the habitat structure the following spring. The dyke was repaired in the fall of 2005 followed by a significant increase in the water level. The fluctuating Least Bittern abundance observed during these years suggests a rapid response of the local population to interannual changes in water level and habitat structure. Water-level management may be necessary to ensure long-term ecological integrity of artificial wetlands but management activities should be conducted outside the breeding season to ensure that the Least Bittern's reproductive needs are fulfilled.

A Horned Screamer (Anhima cornuta) population was studied to examine its conservation status and habitat deterioration in the El Canclon Lagoon wetland (Manglares Churute Ecologic Reserve) at coastal Ecuador from February 2001 to January 2002. Weekly censuses were conducted along 100m transects around the lagoon perimeter in five survey areas, showing different degree of perturbation, during the dry and wet seasons. At least 68 screamers were observed in the lagoon. The abundance of screamers was lower (six-ten individuals) in more disturbed areas containing farms, agriculture fields and cattle ranching. Abundance was inversely associated with the presence of cattle and was not seasonally dependent during the dry and wet seasons. Screamers were significantly associated with vegetation coverage. Because the Horned Screamer strongly relies on the wetland vegetation, cattle overgrazing jeopardizes its habitat and survival in this Ramsar wetland. Best management practices and the establishment of buffer zones (i.e. 100m) are needed to mitigate the agriculture expansion and cattle ranching around the El Canclon lagoon in order to protect this threatened Anseriformes species in Ecuador.

We assessed the effects of capture period, capture subregion, age, sex and habitat conditions on the body condition of migrating and wintering Northern Pintails (Anas acuta) in the Playa Lakes Region (PLR) of northwestern Texas. Body condition varied with sex, age, subregion and month during the wet 2002. During 2002, after-hatch-year (AHY) males had more carcass fat (g and percent) than did AHY females. Likewise, AHY males had 34% more carcass fat (g) than hatch-year (HY) males, but we did not detect differences between AHY and HY females. The average increase in carcass fat (g) from October to November-December during wet 2002, was 26% for males and 42 to 93% (HY) for females. Body condition of pintails in the south exceeded those captured in northern subregions of the PLR during wet 2002, but not dry 2003. Southern caught AHY males had 31% more carcass fat (g) than northern caught AHY males, but we found no differences for HY males. Females caught in southern subregions also had 24–77% more carcass fat (g) than northern captured females. During dry 2003, pintail carcass fat (g and %) did not vary by capture location or among age and sex classes, except for males, which increased carcass fat by 34% between capture periods. From our findings, we recommend that managers periodically assess pintail body condition to detect temporal trends of condition status and measure population response to conservation efforts. However, use of body condition measures to evaluate habitat management and conservation efforts must be evaluated in the context of habitat conditions, sample locations, period of sample collection and age and sex classes.

We analyzed carcass lipid, ash and protein dynamics of male and female Wilson's Snipe (Gallinago gallinago delicata) from arrival on wintering areas in coastal Texas until departure for spring migration. In addition, we analyzed seasonal variation in mass and length of digestive organs to document changes that may increase gut capacity and digestive efficiency of migrating and wintering Wilson's Snipe. Lipid reserves of female snipe remained relatively stable from fall to winter, whereas body protein increased by 3% during this time. Females catabolized lipids and protein prior to spring migration. Conversely, lipid reserves of male snipe increased by 44% from fall to winter and were at least maintained from winter to spring. Furthermore, we observed a trend (P = 0.021) for increasing lipid content in males during spring. Because male snipe accumulate fat reserves prior to spring departure, it appears they employ a “time-selected” strategy for spring migration. In contrast, female snipe migrate later in spring when food may be more available. Thus, females apparently rely more on dietary nutrients acquired at migration stopover sites to and likely employ an “energy-selected” strategy for spring migration. Gut morphology of male snipe remained unchanged throughout the non-breeding period whereas length of small intestine, caeca, and large intestine decreased by 6%, 8% and 8%, respectively from fall to winter in females. Small intestine length increased by 6% in females from winter to spring.

Little information exists on breeding Greater Sandhill Cranes (Grus canadensis tabida) in riparian wetlands of the Intermountain West. We examined the nesting ecology of Sandhill Cranes associated with riparian and palustrine wetlands in the Henry's Fork Watershed in eastern Idaho in 2003. We located 36 active crane nests, 19 in riparian wetlands and 17 in palustrine wetlands. Nesting sites were dominated by rushes (Juncus spp.), sedges (Carex spp.), Broad-leaved Cattail (Typha latifolia) and willow (Salix spp.), and adjacent foraging areas were primarily composed of sagebrush (Artemisia spp.), cinquefoil (Potentilla spp.),Rabbitbrush (Ericameria bloomeri) bunch grasses, upland forbs, Quaking Aspen (Populus tremuloides) and cottonwood (Populus spp.). Mean water depth surrounding nests was 23 cm (SD = 22). A majority of nests (61%) were surrounded by vegetation between 30–60 cm, 23% by vegetation <30 cm, and 16% by vegetation >60 cm in height. We were able to determine the fate of 29 nests, of which 20 were successful (69%). Daily nest survival was 0.986 (95% LCI 0.963, UCI 0.995), equivalent to a Mayfield nest success of 0.654 (95% LCI 0.324, UCI 0.853). Model selection favored models with the covariates vegetation type, vegetation height, and water depth. Nest survival increased with increasing water depth surrounding nest sites. Mean water depth was higher around successful nests (30 cm, SD = 21) than unsuccessful nests (15 cm, SD 22). Further research is needed to evaluate the relative contribution of cranes nesting in palustrine and riparian wetlands distributed widely across the Intermountain West.

Nest site characteristics and reproductive success of Black-crowned Night Herons Nycticorax nycticorax, Little Egrets Egretta garzetta and Grey Herons Ardea cinerea were studied in a heronry in Pyeongtaek, Gyeonggido, Korea. When the species nested in trees without other conspecifics, the mean height of the nest from the ground and the mean distance of nest from the tree trunk differed among species. In trees where both Black-crowned Night Herons and Little Egrets nested, mean nest height did not differ between species, but Black-crowned Night Herons nested, on average, farther from the tree trunk. In trees where Black-crowned Night Herons and Grey Herons nested, the mean distance of nest from the tree trunk for Black-crowned Night Herons was greater, but the mean nest height did not differ between species. In trees where all three species nested, the mean nest height from the ground for Black-crowned Night Herons and Grey Herons was higher than for Little Egrets, and the mean distance of nest from the tree trunk for Black-crowned Night Herons was greater than for the other species. Clutch size did not differ significantly among herons and egrets. Black-crowned Night Herons had fewer hatchlings and fledglings than did the other species. We suggest that while nest height from the ground for herons and egrets was not related to reproductive success, the distance of the nest from the tree trunk was so related.

During a time of food stress, we observed sex-biased mortality during the nestling stage in a sexually size dimorphic species of wading bird, the White Ibis (Eudocimus albus). Over four days spread out over a week, we captured a total of 180 25–32 d old White Ibis nestlings from a colony of several thousand breeding pairs. On sequential capture dates we caught significantly fewer females than males. Through this time period male nestlings had higher body condition indices (mass/tarsus) than females, though the rates at which male and female body condition increased over the week were not significantly different. Several sources of evidence suggest that our sampling was not sex-biased and was reflective of actual changes in abundance of males and females. These data indicate that despite the greater caloric requirements of males, their larger size may have conferred a competitive advantage over female siblings in obtaining food from parents during a time of food shortage.

Attempts of interbrood food theft (food kleptoparasitism) from chicks of Grey Heron (Ardea cinerea) by foreign nestlings are reported from three heronries situated in northern Poland. Such behavior was observed more often in two of the three sites studied. In one colony, it was recorded occasionally. Possible reasons of intercolonial differentiation in food theft attempts occurrence are discussed.

We implanted satellite transmitters into eight juvenile Common Mergansers to investigate post-fledging movements from their natal river in southcentral Alaska. Subsequently, they moved widely throughout portions of western and southcentral Alaska up to 750 km from their natal areas during fall and winter months. Transmitters of two birds (one male and one female) continued to send location data into their second year and allowed us to determine the location and timing of the flightless molt period for each bird. Overall, our data suggest that juvenile Common Mergansers range widely immediately after fledging, that second year males and females may differ in their movement patterns, and that these movements have implications for population genetic structure of this species.

Tens of thousands of shorebirds use saline lakes as migratory stopovers in the Southern Great Plains, USA. To assess their foraging strategies and understand how they replenish energy reserves during spring and summer/fall migrations, we examined diets, prey taxa selection, and prey size selection of American Avocets (Recurvirostra americana), Least Sandpipers (Calidris minutilla), Wilson's Phalaropes (Phalaropus tricolor), and Lesser Yellowlegs (Tringa flavipes). Migrant shorebirds foraged opportunistically by taking most prey taxa according to their availability. Least Sandpipers preferred small prey (2–5 mm), whereas American Avocet, Wilson's Phalaropes, and Lesser Yellowlegs generally preferred intermediate and large prey (6–20 mm). By consuming prey taxa according to their availability and prey sizes that require minimum energy to capture and ingest, shorebirds increase their ability to replenish energy reserves while migrating through interior North America. Drought and drying of freshwater springs will reduce availability of prey in saline lakes for migrating shorebirds. To preserve the saline lakes as important habitats where shorebirds replenish nutrient reserves while migrating through the Great Plains, it is important to conserve groundwater so that freshwater springs continue to discharge into the lakes.

The foraging and diving behavior of the Great Grebe (Podicephorus major) was studied in southern Brazil, from June to October 2005. A total of 547 dives performed by adult birds and 578 dives of juveniles were recorded. There was no age-related difference in dive duration (adults = 19.43 s; juveniles = 20.00 s) but the time elapsed between two successive dives (pause or recovery time) differed among age-classes (adults = 16.1 s; juveniles = 15.0 s). Duration of dive and pause times were weakly correlated in adults and not correlated in juveniles. Both age classes had feeding bouts of similar durations. Adults were more efficient in capturing prey (0.2 prey/min) in comparison with juveniles (0.1 prey/min) and took significantly larger prey. The main food item was the White Croaker (Micropogonias furnieri), an abundant demersal fish in the area. Juveniles had higher prey handling time in comparison with adults (78.2 s vs. 20.1 s), making them more prone than adults to being cleptoparasitized by other seabirds. Diving duration varied during daytime hours, with juveniles diving longer during early morning and late afternoon, while adults avoided foraging during midday hours. Feeding throughout the day could be a mechanism used by juvenile grebes to compensate for low foraging efficiency.

In austral spring 2006, a year of severe drought conditions, we timed 314 and 133 dives and subsequent surface durations of Hoary-headed (Poliocephalus poliocephalus) and Australasian Little Grebes (Tachybaptus novaehollandiae), respectively, at a freshwater lake in southern Australia. Hoary-headed Grebes stayed submerged for longer (18.5 ± 3.6 s) than Australasian Little Grebes (15.7 ± 4.2 s and 2.1 ± 1.1, respectively). Consequently, Hoaryheaded Grebes maintained a high and constant diving efficiency (2.33 ± 0.25)—measured as the dive:pause ratio— throughout the study, suggesting that they are better at facing changes in water level of their lacustrine environment than Australasian Little Grebes, which showed an erratic and lower (1.95 ± 0.48) dive efficiency.

This paper reports the first record of the Green Heron (Butorides virescens) nesting on the oceanic islands of Bermuda. Nesting was first documented in 2002; nests were first found in 2003. From 2005–2007, the Green Heron nesting population was about 20 pairs, located at as many as seven sites dispersed over most of the islands. It is likely that the Green Heron nested on Bermuda for some years immediately before its discovery. A review of available information suggests that it may have nested also on Bermuda in pre-colonial times, possibly even into the historic period. During the study period, over 80 young have fledged at the two main nesting sites. Green Herons on Bermuda eat small fish at inland ponds and marshes and along the coast. This paper also provides the first published description of the occurrence, in 1985–1990, of the Striated Heron (Butorides striata) on Bermuda. Colonization of the Green Heron followed private and government engagement in wetland conservation action, which likely provided habitat required for the colonization event to be successful.

This study compares the plumage of a single Eurasian White-throated Dipper Cinclus cinclus with that of three Common (European) Blackbirds Turdus merula (all road casualties). As expected, the Dipper had far more down and contour feathers (3,322) than the Blackbirds (mean 1,704), with Dipper down and contour feathers being significantly shorter than those of Blackbirds. However, contrary to published information, the plumage of dippers is not exceptionally dense; the mean follicle density of the Dipper was 59.2 follicles cm^-2, that of the Blackbirds 58.6–61.7 follicles cm^-2. Instead, the enhanced insulation of diving Dippers stems from a) much more extensive plumage (the apterylae between feather tracts are fully feathered, whilst naked in Blackbirds), b) substantial down cover of head (absent in Blackbirds), c) extensive down cover of wings. Much of the higher number of feathers in the Dipper is made up of contour feathers rather than down/semiplume feathers (the ratio between Dipper contour and down/semiplume feathers, 3.35:1, was similar to that of Blackbirds, 3.55:1), indicating an insulative function for contour feathers as well as down. Ultrastructural investigation showed that Dipper breast and back down was substantially finer (more complex) than in Blackbirds, but leg down, and contour feathers of the two species were indistinguishable.

Red-footed Boobies (Sula sula) belong to the Sulidae family and the order Pelicaniformes and are expected to present low rates of extra-pair paternity (EPP) due to several life history traits of seabirds. We found no evidence of EPP among 14 families of Red-footed Boobies nesting on Genovesa Island in the Galápagos archipelago using multilocus minisatellite DNA markers. The band-sharing values between parents and offspring ranged from 0.44 to 0.86 and those among unrelated individuals ranged from 0.07 to 0.4; all bands in offspring lanes were accounted for by those in the lanes of the putative parents.

Depth recorders are among the most useful tools available for ornithologists interested in waterbird foraging behavior. Despite their widespread use in the literature, there is little information available about their precision and accuracy, including, for the case of TDRs, device drift. We examined the uncertainty associated with two types of depth-recorders deployed on Thick-billed Murres Uria lomvia in the Canadian Arctic in 2007 for up to 48 hours. The maximum depth obtained by capillary tube maximum-depth gauges (MDGs), a cheap and simple depth-recorder, was highly correlated (R² = 0.87) with maximum depth obtained by electronic time-depth recorders (TDRs) attached to the same bird (n = 29) up to depths of 100 m. Deeper than 100 m or in deployments of 144 hours, MDGs were unreliable. We suggest that the maximum depth for Thick-billed Murres in the Canadian Arctic is about 150 m, rather than the 210 meters previously reported using MDGs recorders, and that caution should be used when quoting maximal maximum depths for species diving deeper than 100 m using this method. We also attached two Lotek TDRs to the same bird (n = 18) and examined the similarity of the two recorders. The average difference increased from about 0.5 m near the surface to about 1.0 m below 60 m, with extreme differences of up to 4 m obtained. Furthermore, TDRs submerged to known depth were accurate within ± 2 m. The effect of these variations on measurements of maximum and average depth and duration was about 0.6–1.3 m (depth) or s (duration), which is similar to the manufacturer's accuracy specifications (±1%). Finally, we examined the drift (offset from zero at the surface) within the TDRs. Drift varied from -2.5 to 2 m, with 9 out of 36 recorders showing no drift, and no change amongst years for individual recorders. Drift was lowest (most negative) at the colony, higher during flight and highest (most positive) on the water surface, despite very small differences in altitude (<50 m). We suggest that drift may be a useful tool for quantifying at-sea behavior, especially in conjunction with temperature logs. We conclude that MDGs are reliable up to 100 m and within 48 hours, and that TDRs are precise within ±2%, but that more research needs to be completed on device accuracy and precision.