Geology topics

Melissa A. Althouse

Publications and source records attributed to Melissa A. Althouse.

3 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↗