Geology topics

Mark Maftei

Publications and source records attributed to Mark Maftei.

4 recordsLinked to original sources

USGS2025

Evaluating effects of tracking device attachment methods on Black Oystercatchers Haematopus bachmani

Advances in tracking technology are greatly improving our understanding of many aspects of avian ecology. However, the diversity of tracking devices and attachment methods necessitates better evaluation of how they affect particular taxa. We evaluated effects of tracking devices mounted on leg bands or attached using leg-loop harnesses on resighting rates of Black Oystercatchers Haematopus bachmani in Alaska and British Columbia. In Alaska, in 2019, geolocators were mounted on a leg band (n = 20) or encased in a nylon mount and attached using a leg-loop harness (n = 20), and GPS devices were attached using a leg-loop harness (n = 6). In British Columbia, Argos-PTT satellite transmitters were attached using a leg-loop harness (n = 26) in 2019 and 2020. Control birds were colour-banded (Alaska: n = 22; British Columbia: n = 27) but were not equipped with a tracking device. Surveys to resight birds with and without tracking devices were conducted in 2020 and 2021. Birds carrying geolocators, GPS devices, and Argos-PTT satellite transmitters attached using a leg-loop harness were as likely to be resighted (69% in Alaska and 62% in British Columbia) as control birds (59% in both areas). However, birds carrying geolocators mounted on leg bands were far less likely to be resighted (15%). We also used resighting data and a time-to-tag failure analysis to obtain a minimum annual survival estimate for the birds carrying an Argos-PTT satellite transmitter. The minimum annual survival estimate for these birds (0.81 ± 0.08 SE) did not differ from previously reported annual apparent survival estimates for Black Oystercatchers in British Columbia (0.91 ± 0.02 SE). These findings suggest that while Black Oystercatchers can successfully carry tracking devices weighing less than 3% of their body mass when attached using a leg-loop harness, they are negatively affected by small tracking devices mounted directly on leg bands.

Wader Study↗

USGS2024

Latitudinal gradients and sex differences in morphology of the Black Oystercatcher (Haematopus bachmani)

Environment and behavior are widely understood to affect bird morphology, which can lead to differences among subspecies or populations within a wide-ranging species. Several patterns of latitudinal gradients in morphology have been described, though Allen's and Bergmann's rules are the most well-known and have been tested and confirmed across a diversity of taxa and species. These state that individuals at higher latitudes will have larger bodies (Bergmann's Rule) but smaller extremities (Allen's Rule) to conserve heat in colder climates. Migratory behavior also can influence avian morphology, particularly wing shape, where migratory birds tend to have longer, more pointed wings than residents. The Black Oystercatcher ( Haematopus bachmani ) is a large, partially migratory shorebird species restricted to intertidal habitats and distributed from Alaska to Baja California, spanning about 35° of latitude. A large proportion of Black Oystercatchers that breed in Alaska are migratory, where nearly all individuals breeding in British Columbia through the southern end of their range remain resident through the annual cycle. Their broad latitudinal range and diversity in migratory behavior may drive geographic variation in morphology. Here we evaluate three explanations for geographic variation in morphology of the Black Oystercatcher using data from seven sites across two regions: Alaska and British Columbia. We found evidence consistent with Allen's but not Bergmann's rule; birds in Alaska have shorter bills than those in British Columbia, and these findings held when controlling for body size using wing length. Despite regional differences in migratory behavior, we detected no difference in the wing shape of birds in Alaska and British Columbia. Differences between sexes and among sites suggest that multiple factors drive patterns of morphological variation in the Black Oystercatcher.

Alaska↗

USGS2020

Ecological insights from three decades of animal movement tracking across a changing Arctic

The Arctic is entering a new ecological state, with alarming consequences for humanity. Animal-borne sensors offer a window into these changes. Although substantial animal tracking data from the Arctic and subarctic exist, most are difficult to discover and access. Here, we present the new Arctic Animal Movement Archive (AAMA), a growing collection of more than 200 standardized terrestrial and marine animal tracking studies from 1991 to the present. The AAMA supports public data discovery, preserves fundamental baseline data for the future, and facilitates efficient, collaborative data analysis. With AAMA-based case studies, we document climatic influences on the migration phenology of eagles, geographic differences in the adaptive response of caribou reproductive phenology to climate change, and species-specific changes in terrestrial mammal movement rates in response to increasing temperature.

Science↗

USGS2014

Quantifying fall migration of Ross's gulls (Rhodostethia rosea) past Point Barrow, Alaska

The Ross’s gull ( Rhodostethia rosea ) is a poorly known seabird of the circumpolar Arctic. The only place in the world where Ross’s gulls are known to congregate is in the near-shore waters around Point Barrow, Alaska, where they undertake an annual passage in late fall. Ross’s gulls seen at Point Barrow are presumed to originate from nesting colonies in Siberia, but neither their origin nor their destination has been confirmed. Current estimates of the global population of Ross’s gulls are based largely on expert opinion, and the only reliable population estimate is derived from extrapolations from previous counts conducted at Point Barrow, but these data are now over 25 years old. In order to update and clarify the status of this species in Alaska, our study quantified the timing, number, and flight direction of Ross’s gulls passing Point Barrow in 2011. We recorded up to two-thirds of the estimated global population of Ross’s gulls (≥27,000 individuals) over 39 days with numbers peaking on 16 October when we observed over 7,000 birds during a 3-h period.

Alaska↗