A Population Estimate for Golden Eagles in the Western United States

ABSTRACT Researchers have suggested golden eagle (Aquila chrysaetos) populations may be declining in portions of their range. However, there are few baseline data describing golden eagle populations across their range in the western United States. We used aerial line transect distance methodology with a double-observer modification to estimate golden eagle population numbers in 4 bird conservation regions of the western United States. We conducted surveys from 16 August to 8 September 2003, after most golden eagles had fledged and before fall migration. The goal of our sampling strategy was to provide >80% power (α = 0.1) to detect an annual rate of total population change >3% per year over a 20-year period. We observed 172 golden eagles across 148 transects and estimated 27,392 golden eagles (90% CI: 21,352-35,140) occurred in the study area during the late summer and early fall of 2003. Following the surveys, we used Monte Carlo simulation to determine the statistical power to detect trends in the golden eagle populations if yearly surveys were continued over a 20-year monitoring period. The simulation indicated the desired power could be achieved under the current methodology and sample size. The methods utilized in this study can be implemented for other raptor species when population estimates that include nonbreeding members of a population are needed. The results of this study can be utilized by professionals to help manage golden eagle populations and to develop conservation strategies.     

Meristems under Continuous Irradiation

Root tips of Vicia faba and Zea mays have been subjected tocontinuous irradiation from radium or cobalt-60 for long periodsat various dose rates. The rates of mitosis and the damage tothe chromosomes (assessed as percentages of cells with micronulei)have been measured in four regions of the meristems. In Zearates of mitosis are reduced under chronic irradiation, exceptin the quiescent centre, and the cap initials are particularlysensitive. In Vicia the main change in mitosis is that the quiescentcentre increases its rate, but at 12°C there is a slightstimulation of division all over the meristem. In Vicia increasingthe dose rate or lowering the temperature increases the nucleardamage. At 19° C there is an increase in damage with accumulateddose percell cycle, but the data at 12°C do not fall onthe 19°C curve, suggesting that there may be a temperatureeffect on damage other than that caused by changing the durationof the cell cycle. The differences in radiosensitivity betweenthe different regions of the meristem are due solely to differencesin the rates of mitosis of the cells.     

Circadian rhythm of proboscis extension responsiveness in the blowfly: central control of threshold changes

ABSTRACT. The proboscis extension response of the blowfly, Protophormia terraenovae (R.-D.), elicited by stimulation of the tarsi with sucrose, was studied behaviourally under LD 12:12. A diel rhythm in responsiveness was found that occurred at successively higher daily mean levels as the test flies became increasingly starved. This rhythm persisted for at least one cycle in constant light, demonstrating it to be truly endogenous and circadian. The tarsal chemo-receptors concerned in initiating the response were examined electrophysiologically in whole fly preparations. No daily change occurred in the response of these receptors to sucrose. Hence central control of the behavioural rhythm of response to sucrose is inferred, and a model is proposed which incorporates a circadian oscillator into the currently accepted model for the control of proboscis extension thresholds.     

Chlorophyll Destruction in Lemon Fruit by Light and 2',4'Dichloro 1-Cyanoethane-sulphonanilide

Chlorophyll content decreased when excised lemon fruits were exposed to light. A quantitative model for the photodestruction of chlorophyll exhibited reasonable agreement with data on in vivo destruction of chlorophyll. Photodestruction of chlorophyll was enhanced by treating fruit with 2′,4′-dichloro-l-cyanoethane-sulphonanilide (R33417). Measurable enhancement of chlorophyll destruction was observed with concentrations of R33417 as low as 10 μg/l. Maximum activity was achieved at approximately 600 μg/1. R33417 treatment enhanced photodestruction of chlorophyll to a greater extent at higher photon flux densities.