Intraspecific Intrusion at Bald Eagle Nests

Competition for nesting territory has been shown to act as a density-dependent feedback mechanism influencing population growth rate. However, little is known about the nature of territorial interactions between established breeders and floaters. We examined territorial intrusion rates and associated behaviours at active Bald Eagle Haliaeetus leucocephalus nests in the lower Chesapeake Bay in 2012 and 2013. The average intrusion rate experienced at study nests during the reproductive period was 0.28 ± 0.32 intrusions/h. Variance in intrusion rate was high and there was no apparent predictive pattern to these events. Juvenile intrusions occurred closer to the nest than adult intrusions, and breeders showed higher response rates toward adults, with 78% of adult intruders eliciting a response compared to 47% of juveniles. Breeding adults responded to intruders significantly more often and more aggressively when in the presence of their mate. Further research is necessary to broadly describe the relationship between intrusion frequency and the frequency of nest failure

Nest Guarding in Chesapeake Bay Bald Eagles

As Bald Eagle (Haliaeetus leucocephalus) populations approach carrying capacity in the Chesapeake Bay, competition for breeding territories appears to be intensifying. Frequent territorial interactions may force breeders to adjust nest-guarding behavior. We examined nest-guarding behaviors at active Bald Eagle nests in the lower Chesapeake Bay during the nesting season (2012 and 2013). Guarding coverage was 13.7 ± 4.2% of total observation time during the pre-laying period, 6.8 ± 2.2% of observation time in the incubation period, and 26.3 ± 3.2% of observation time in the nestling period. Females were present in the nest area for 80.0 ± 2.7% of the nestling period. Although males were present only 51.2 ± 2.8% of the nestling period, male breeders guarded nests twice as often as females. Adults guarded most often from perches in adjacent trees and within 25 m of the nest. If increasing rates of conspecific interactions force males to allocate more time to nest guarding, a tradeoff may occur, with males dividing time between guarding the nest and foraging for food to provision offspring. A medida que las poblaciones de Haliaeetus leucocephalus se acercan a la capacidad de carga en Chesapeake Bay, parece intensificarse la competencia por los territorios de cría. Las interacciones territoriales frecuentes pueden forzar a las parejas reproductivas a adaptar su comportamiento de custodia de los nidos. Examinamos diversos comportamientos de custodia de nidos activos de H. leucocephalus en la región baja de Chesapeake Bay durante la época de cría (2012 y 2013). El comportamiento de custodia ocupó el 13.7 ± 4.2% del tiempo total de observación durante el periodo previo a la puesta, el 6.8 ± 2.2% del tiempo de observación en el periodo de incubación y el 26.3 ± 3.2% del tiempo de observación en el periodo de estancia de los pollos en el nido. Las hembras estuvieron presentes en el área del nido durante el 80.0 ± 2.7% del periodo de estancia de los pollos en el nido. Aunque los machos estuvieron presentes sólo el 51.2 ± 2.8% del periodo de estancia de los pollos en el nido, los machos reproductores protegieron sus nidos el doble de veces que las hembras. Los adultos desplegaron comportamientos de protección con mayor frecuencia desde posaderos ubicados en los árboles adyacentes al nido y en un radio de 25 m alrededor del mismo. Si las crecientes tasas de interacción intra-específicas obligan a los machos a emplear más tiempo en la protección del nido, esto puede resultar en un compromiso en el que los machos tengan que dividir su tiempo entre la protección del nido y la búsqueda de comida para la provisión de su prole

Mapping Bald Eagle Activity Shadows Around Communal Roosts

We assessed diurnal activity patterns associated with communal roosts (n = 26) by tracking nonbreeding bald eagles (Haliaeetus leucocephalus; n = 58) within the upper Chesapeake Bay, USA, 2008-2013. We used daytime locations (n = 54,165) to map activity shadows (using home range analytics, 90% kernel) around communal roosts, to evaluate the spatial structure and to delineate diurnal activity centers. We overlaid a range (100-3,200 m) of buffers around the perimeter of each roost to estimate the benefits of management scenarios in extending protection to daytime activities. Activity shadows around roosts varied from 1.5 km(2) to 116 km(2) ((x) over bar = 30.3 +/- 5.48 [SE]), reflecting landscape context. Roosts with small (\u3c 10 km(2)) activity shadows tended to have simple shapes with roosts centrally located and positioned along primary shorelines. Roosts supporting large (\u3e 50 km(2)) activity shadows tended to have complex shapes with roosts not centrally located and set back from primary shorelines. Daytime locations were highly concentrated in areas near communal roosts (76% of locations within 2 km of roost perimeters). Diurnal activity centers (n = 38) included areas surrounding roosts and secondary activity centers that were primarily located along prominent shorelines. Communal roosts play a more significant and multi-faceted role in the eagle life cycle than we previously understood. Many of the roosts positioned along the shoreline provided resting places during the night and day, served as social gathering places during the day, and functioned as feeding locations. Evaluation of management buffers supports current management guidelines that recommend the establishment of 800-m buffers. Establishment of 800-m buffers within the study area would enclose 54% of all daytime locations, 66.7% of the area enclosed within activity centers associated with roosts, and 12.1% of the area enclosed in secondary activity centers. (C) 2017 The Wildlife Society

Effects of bedrock lithology and subglacial till on the motion of Ruth Glacier, Alaska, deduced from five pulses from 1973 to 2012

pre-printA pulse is a type of unstable glacier flow intermediate between normal flow and surging. Using Landsat MSS, TM and ETM+ imagery and feature-tracking software, a time series of mostly annual velocity maps from 1973 to 2012 was produced that reveals five pulses of Ruth Glacier, Alaska. Peaks in ice velocity were found in 1981, 1989, 1997, 2003 and 2010, approximately every 7 years. During these peak years the ice velocity increased 300%, from approximately 40ma-1 to 160ma-1. Based on the spatio-temporal behavior of Ruth Glacier during the pulse cycles, we suggest the pulses are due to enhanced basal motion via deformation of a subglacial till. The cyclical nature of the pulses is interpreted to be due to a thin till, with low permeability, that causes incomplete drainage of the till between the pulses, followed by eventual recharge and dilation of the till. These findings suggest care is needed when attempting to correlate changes in regional climate with decadal-scale changes in velocity, because in some instances basal conditions may have a greater influence on ice dynamics than climate

Landfill Use by Bald Eagles in the Chesapeake Bay Region

We examined patterns in the use of landfills (rubbish dumps) in the Chesapeake Bay by Bald Eagles (Haliaeetus leucocephalus). Sites of solid waste landfills (n  =  72) were located using state databases. Satellite tracking data from 64 eagles were used to track eagle movements hourly during daylight and once at midnight to determine roosting locations (2007–2012). Landfill use varied significantly with age class, with hatch-year birds using landfills six times more often than adults and twice as often as third- and fourth-year birds. Hatch-year birds spent significantly more time at landfills than expected based on landfill area relative to the study area outside of landfills. The relationship between time of year and eagle presence at landfills was not significant, though the results suggest a peak in landfill use in the late fall. There was spatial variation in landfill use, with 10% of the landfills used by study birds receiving 75% of the total landfill use. Landfills within two km of communal roosts received significantly more eagle activity than landfills farther from communal roosting sites. If eagle presence at landfills is indicative of foraging at these sites, the results provide evidence that foraging strategies in Bald Eagles change with age. Landfills may serve as important scavenging sites for hatch-year and second-year eagles, whereas older birds may be more successful obtaining higher quality prey elsewhere

Utilization Probability Map for Migrating Bald Eagles in Northeastern North America: A Tool for Siting Wind Energy Facilities and Other Flight Hazards

Collisions with anthropogenic structures are a significant and well documented source of mortality for avian species worldwide. The bald eagle (Haliaeetus leucocephalus) is known to be vulnerable to collision with wind turbines and federal wind energy guidelines include an eagle risk assessment for new projects. To address the need for risk assessment, in this study, we 1) identified areas of northeastern North America utilized by migrating bald eagles, and 2) compared these with high wind-potential areas to identify potential risk of bald eagle collision with wind turbines. We captured and marked 17 resident and migrant bald eagles in the northern Chesapeake Bay between August 2007 and May 2009. We produced utilization distribution (UD) surfaces for 132 individual migration tracks using a dynamic Brownian bridge movement model and combined these to create a population wide UD surface with a 1 km cell size. We found eagle migration movements were concentrated within two main corridors along the Appalachian Mountains and the Atlantic Coast. Of the 3,123 wind turbines \u3e= 100 m in height in the study area, 38% were located in UD 20, and 31% in UD 40. In the United States portion of the study area, commercially viable wind power classes overlapped with only 2% of the UD category 20 (i.e., the areas of highest use by migrating eagles) and 4% of UD category 40. This is encouraging because it suggests that wind energy development can still occur in the study area at sites that are most viable from a wind power perspective and are unlikely to cause significant mortality of migrating eagles. In siting new turbines, wind energy developers should avoid the high-use migration corridors (UD categories 20 & 40) and focus new wind energy projects on lower-risk areas (UD categories 60-100)

A Methodology for daylight optimisation of high-rise buildings in the dense urban district using overhang length and glazing type variables with surrogate modelling

Urbanization and population growth lead to the construction of higher buildings in the 21st century. This causes an increment on energy consumption as the amount of constructed floor areas is rising steadily. Integrating daylight performance in building design supports reducing the energy consumption and satisfying occupants' comfort. This study presents a methodology to optimise the daylight performance of a high-rise building located in a dense urban district. The purpose is to deal with optimisation problems by dividing the high-rise building into five zones from the ground level to the sky level, to achieve better daylight performance. Therefore, the study covers five optimization problems. Overhang length and glazing type are considered to optimise spatial Daylight Autonomy (sDA) and Annual Sunlight Exposure (ASE). A total of 500 samples in each zone are collected to develop surrogate models. A self-adaptive differential evolution algorithm is used to obtain near-optimal results for each zone. The developed surrogate models can estimate the metrics with minimum 98.25% R2 which is calculated from neural network prediction and Diva simulations. In the case study, the proposed methodology improves daylight performance of the high-rise building, decreasing ASE by approx. 27.6% and increasing the sDA values by around 88.2% in the dense urban district. - Published under licence by IOP Publishing Ltd.We would like to thank Cemre Cubukcuoglu for the collaborative work while implementing the optimisation algorithm. M. Fatih Tasgetiren, who is partially supported by the National Natural Science Foundation of China (Grant No. 51435009), acknowledges the HUST project in Wuhan.Scopu

The growth and erosion of cinder cones in Guatemala and El Salvador: Models and statistics

Morphologic data for 147 cinder cones in southern Guatemala andwestern El Salvador are comparedwith data from the San Francisco volcanic field, Arizona (USA), Cima volcanic field, California (USA), Michoácan–Guanajuato volcanic field, Mexico, and the Lamongan volcanic field, East Java. The Guatemala cones have an average height of 110+/-50 m, an average basal diameter of 660+/-230 m and an average top diameter of 180+/-150 m. The generalmorphology of these cones can be described by their average cone angle of slope (24+/-7), average heightto- radius ratio (0.33+/-0.09) and their flatness (0.24+/-0.18). Although the mean values for the Guatemalan cones are similar to those for other volcanic fields (e.g., San Francisco volcanic field, Arizona; Cima volcanic field, California; Michoácan–Guanajuato volcanic field, Mexico; and Lamongan volcanic field, East Java), the range of morphologies encompasses almost all of those observed worldwide for cinder cones. Three new 40Ar/39Ar age dates are combined with 19 previously published dates for cones in Guatemala and El Salvador. There is no indication that the morphologies of these cones have changed over the last 500–1000 ka. Furthermore, a re-analysis of published data for other volcanic fields suggests that only in the Cima volcanic field (of those studied) is there clear evidence of degradation with age. Preliminary results of a numerical model of cinder cone growth are used to show that the range of morphologies observed in the Guatemalan cinder cones could all be primary, that is, due to processes occurring at the time of eruption

The growth and erosion of cinder cones in Guatemala and El Salvador: Models and statistics

Morphologic data for 147 cinder cones in southern Guatemala andwestern El Salvador are comparedwith data from the San Francisco volcanic field, Arizona (USA), Cima volcanic field, California (USA), Michoácan–Guanajuato volcanic field, Mexico, and the Lamongan volcanic field, East Java. The Guatemala cones have an average height of 110+/-50 m, an average basal diameter of 660+/-230 m and an average top diameter of 180+/-150 m. The generalmorphology of these cones can be described by their average cone angle of slope (24+/-7), average heightto- radius ratio (0.33+/-0.09) and their flatness (0.24+/-0.18). Although the mean values for the Guatemalan cones are similar to those for other volcanic fields (e.g., San Francisco volcanic field, Arizona; Cima volcanic field, California; Michoácan–Guanajuato volcanic field, Mexico; and Lamongan volcanic field, East Java), the range of morphologies encompasses almost all of those observed worldwide for cinder cones. Three new 40Ar/39Ar age dates are combined with 19 previously published dates for cones in Guatemala and El Salvador. There is no indication that the morphologies of these cones have changed over the last 500–1000 ka. Furthermore, a re-analysis of published data for other volcanic fields suggests that only in the Cima volcanic field (of those studied) is there clear evidence of degradation with age. Preliminary results of a numerical model of cinder cone growth are used to show that the range of morphologies observed in the Guatemalan cinder cones could all be primary, that is, due to processes occurring at the time of eruption