Geology topics

Jonathan B. Cohen

Publications and source records attributed to Jonathan B. Cohen.

5 recordsLinked to original sources

USGS2019

Begging behavior as an honest signal of need and parent-offspring association during the post-fledging dependency period

Honest signaling mechanisms can function to appropriate care to hungry offspring and avoid misdirected care of unrelated offspring. Begging, the behavior by which offspring solicit food and parental care, may be an honest signaling mechanism for need, as well as association of parents and offspring. Roseate terns (Sterna dougallii) exhibit prolonged parental care during the post-breeding staging period, offering an ideal system in which to study begging as an honest signaling mechanism. We conducted focal sampling during two pre-migratory staging seasons (2014 and 2015) at Cape Cod National Seashore, MA to determine whether post-fledging tern begging behavior was an honest signal for need and parent-offspring association. Based on honest signaling theory, we expected begging behavior to be highest during times of high perceived need, and we expected to see a decrease in begging behavior as young terns became increasingly independent of the care-giving parent. Also, we predicted that young terns would be more likely to beg at parents than non-parents. We found that young roseate terns begged at their parents more often than non-parents; however, they did not always beg at parents. Model predictions of begging probability showed a linear relationship between begging and time of day and date of season, such that begging increased with time of day and decreased with date of season, respectively. Our results provide evidence for honest parent-offspring interactions and are inconsistent with parent-offspring conflict theory but suggest that begging may play a complex role in post-fledging parent-offspring interactions.

Massachusetts↗

USGS2019

Residency, recruitment, and stopover duration of hatch-year Roseate Terns (Sterna dougallii) during the pre-migratory staging period

Avian migratory stopover and staging sites represent important energetic bottlenecks and may influence population dynamics as much as breeding or wintering periods. Roseate terns ( Sterna dougallii ) are an ideal species to examine staging demography because >70% of the entire endangered northwest Atlantic population stages at accessible locations around Cape Cod, MA before southward migration. We quantified hatch-year tern weekly residency, weekly recruitment rate into the staging population, and derived weekly staging population growth rate during two post-breeding, pre-migratory staging seasons (2014 and 2015) at Cape Cod National Seashore. We also estimated hatch-year tern staging duration at Cape Cod staging grounds. Tern residency probability at Cape Cod National Seashore during 2014 and 2015 was nearly 1 during the first weeks of the season and decreased steadily over the last four weeks to ~0.5 in the final week of the study. Recruitment rates into the staging population, representing the weekly per capita increase in hatch-year terns during the staging season, indicated that most terns arrived on the staging grounds during the first weeks of the staging season (16 July–19 August). We also identified differences in staging duration between birds from the two breeding regions. Hatch-year terns from the southernmost region spent less time staging at Cape Cod National Seashore than their northern counterparts in both 2014 and 2015. These differences may indicate alternative staging strategies for individuals originating in different regions and possibly reveal differences in conditions between these areas; for example, in the availability of ephemeral prey fish.

Massachusetts↗

USGS2018

Evaluating response distances to develop buffer zones for staging terns

Buffer zones, calculated by flight‐initiation distance (FID), are often used to reduce anthropogenic disturbances to wildlife, but FID can vary significantly across life‐history stages. We examined the behavioral effect of potential natural (gulls and shorebirds) and anthropogenic (pedestrians) disturbance sources to staging roseate ( Sterna dougallii ) and common tern ( S. hirundo ) flocks from July to September in 2014 and 2015 at Cape Cod, Massachusetts, USA. We estimated the proportion of the flock exhibiting different responses to potential disturbance sources as a function of distance, flock size, percent roseate terns, and local disturbance rates, using Bayesian zero‐and‐one inflated beta regression. The proportion of tern flocks responding to the presence of shorebirds by flying was low (0.01 ± 0.001 [SE]) and did not vary by distance or other covariates, whereas the proportion flying in response to gulls increased as distance decreased, with smaller flocks, and with flocks with a larger proportion of roseate terns being more sensitive to gull presence. Prolonged flight response rapidly increased in probability from 0.0 to as much as 1.0 as distance from pedestrians to the flock decreased from 100 m and was much more likely with smaller flocks. Pedestrian activity levels also had an effect on flock responses; those engaged in active behaviors such as jogging were more likely to cause flushing than those engaged in passive behaviors. Terns seemed to view pedestrians as more of a threat than shorebirds and gulls, even though gulls are frequent kleptoparasites of terns. Pedestrians >120 m from a tern flock generally elicited the same probability of flight response as shorebirds and gulls. We recommend managers maintain anthropogenic disturbance levels at or below the intensity of those from natural sources at sites where recreation and wildlife values are both important. Because staging tern flocks may use a variety of areas within a site, we recommend instituting a 100‐m buffer around areas potentially used by staging flocks at Cape Cod, where we studied every location roseate terns are known to use in large numbers. For other sites used by mixed‐species tern flocks, we recommend the use of our field and analytical methods to develop appropriate buffer distances that will keep pedestrians far enough away to reduce the likelihood of flight and other non‐locomotive anti‐predator behaviors. These buffer zones will also benefit other species sensitive to human activity.

Journal of Wildlife Management↗

USGS2016

Quantifying the effects of research band resighting activities on staging terns in comparison to other disturbances

Avian research that involves potential disturbance to the study species may have unintended fitness consequences and could lead to biases in measurements of interest. The effects of band resighting on the behavior of mixed-species flocks of staging waterbirds were evaluated against recreational pedestrian activity that was expected to cause flushing. We found a model with additive effects of distance (near, 0-50 m, or far, 50-200 m) and disturbance type (researcher or pedestrian) best explained flock behaviors. The proportion of staging flocks that flushed in response to pedestrians was greatest when pedestrians were within 50 m of the flock. Virtually no flushes were observed in response to researchers, regardless of distance. These results could assist in alleviating concerns that accepted protocols used for intensive band resighting studies on staging seabirds of special conservation status, such as Roseate ( Sterna dougallii ) and Common ( S. hirundo ) terns, may have adverse effects. Our framework could be used by others to test the effects of similar research on sensitive species.

Waterbirds↗

USGS2009

A Review and Synthesis of the Scientific Information Related to the Biology and Management of Species of Special Concern at Cape Hatteras National Seashore, North Carolina

The U.S. Geological Survey's Patuxent Wildlife Research Center (PWRC) conducted a study for the National Park Service (NPS) Southeast Region, Atlanta, GA, and Cape Hatteras National Seashore (CAHA) in North Carolina to review, evaluate, and summarize the available scientific information for selected species of concern at CAHA (piping plovers, sea turtles, seabeach amaranth, American oystercatchers, and colonial waterbirds). This work consisted of reviewing the scientific literature and evaluating the results of studies that examined critical life history stages of each species, and focused on the scientific findings reported that are relevant to the management of these species and their habitats at CAHA. The chapters that follow provide the results of that review separately for each species and present scientifically based options for resource management at CAHA. Although no new original research or experimental work was conducted, this synthesis of the existing information was peer reviewed by over 15 experts with familiarity with these species. This report does not establish NPS management protocols but does highlight scientific information on the biology of these species to be considered by NPS managers who make resource management decisions at CAHA. To ensure that the best available information is considered when assessing each species of interest at CAHA, this review included published research as well as practical experience of scientists and wildlife managers who were consulted in 2005. PWRC scientists evaluated the literature, consulted wildlife managers, and produced an initial draft that was sent to experts for scientific review. Revisions based on those comments were incorporated into the document. The final draft of the document was reviewed by NPS personnel to ensure that the description of the recent status and management of these species at CAHA was accurately represented and that the report was consistent with our work agreement. The following section summarizes the biological information relevant to resource management for the species of concern at CAHA.

Open-File Report↗