Wind drift and the use of radar, acoustics, and Canadian Migration Monitoring Network methods for monitoring nocturnal passerine migration by MICHAEL L. PECKFORD B.Sc. Acadia University, 1999 Thesis submitted in partial fulfillment of the requirements for the Degree of Masters of Science (Biology) Acadia University Spring Convocation 2006 © by MICHAEL L. PECKFORD, 2006 ii This thesis by MICHAEL L. PECKFORD was defended successfully in an oral examination on 07 APRIL, 2006. The examining committee for the thesis was: Dr. Rick Mehta, Chair Dr. Erica Dunn, External Reader Dr. Dave Shutler, Internal Reader Dr. Philip D. Taylor, Supervisor Dr. Dan Toews, Department Head This thesis is accepted in its present form by the Division of Research and Graduate Studies as satisfying the thesis requirements for the degree of Master of Science (Biology). iii Table of Contents List of Tables ..................................................................................................................... iv List of Figures..................................................................................................................... v Abstract............................................................................................................................. vii Acknowledgements..........................................................................................................viii General Introduction ........................................................................................................... 1 Migration and weather .................................................................................................... 1 Monitoring migration...................................................................................................... 6 Chapter 1. Influence of wind on autumn nocturnal avian migratory behaviour in southwestern Nova Scotia ................................................................................................. 8 Introduction......................................................................................................................... 8 Methods............................................................................................................................. 14 Results............................................................................................................................... 18 Discussion......................................................................................................................... 21 Conclusions....................................................................................................................... 26 Chapter 2. Radar, acoustics, and Canada Migration Monitoring Network methods as tools for monitoring nocturnal passerine migration ............................................... 37 Introduction....................................................................................................................... 37 Methods............................................................................................................................. 43 Results............................................................................................................................... 50 Discussion......................................................................................................................... 53 Conclusions and Recommendations ................................................................................. 61 General Discussion ........................................................................................................... 70 Monitoring implications................................................................................................ 70 Population implications ................................................................................................ 71 Limitations and future work.......................................................................................... 72 Literature Cited ................................................................................................................. 73 Appendix 1........................................................................................................................ 80 Appendix 2........................................................................................................................ 80 Appendix 3........................................................................................................................ 90 iv List of Tables Table 1-1. Numbers and proportions of migrants grouped by track bearing over the entire season................................................................................................................................ 36 Table 1-2. Observed proportion of migrants under each wind condition minus the proportion expected if migrants ignore wind conditions. A positive value indicates more than expected migrants were detected (cells bordered by a solid line) and a negative value indicates fewer migrants than expected were detected (bordered by a dashed line), Chi- squared test, p < 0.001. NA indicates wind conditions that did not occur. Wind speed is represented in m/s. ............................................................................................................ 36 Table 1-3. Pearson’s correlation coefficients (r) (and associated p-values) from comparisons between numbers of migrants detected through ground counts and hourly numbers of individuals detected through radar counts during the previous night............ 36 Table 2-1. Description of initial predictor variables used in all generalized linear models ........................................................................................................................................... 67 Table 2-2. Pearson’s correlation coefficients (r) and p values of comparisons between each diurnal monitoring method. ...................................................................................... 67 Table 2-3. Pearson correlation coefficients (r) of numbers of birds detected by diurnal monitoring methods compared to numbers of birds detected by radar per hour on the previous night.................................................................................................................... 67 Table 2-4. Summary of generalized linear models and analysis of variance tests, showing parameter estimates (Est.), standard errors (Std. error), deviance, and degrees of freedom (DF). Census and DETs models have negative binomial distributions, netting model has a Gaussian distribution. For a description of variables see Table 2-1. ................................ 68 Table 2-5. Summary of generalized linear model (negative binomial distribution) and analysis of variance test with nf-call data as the response showing parameter estimates (Estimate), standard errors (Std. error), deviance and degrees of freedom (DF). These data consist of nights with strong directional migration (rho > 0.6 and number of tracks > 100). For description of variables see Table 2-1............................................................... 69 v List of Figures Figure 1-1. Map of Gulf of Maine and surrounding region, indicating the study site, Bon Portage Island.................................................................................................................... 28 Figure 1-2. Schematic of the “doughnut” area surveyed by the radar beam. From Eastwood (1967). .............................................................................................................. 29 Figure 1-3. A bird’s track velocity (T) (direction and speed in relation to the ground) is the resultant vector of its heading velocity (H) (direction and speed in relation to the air) and the wind velocity (W). (a) Drift: Flying at a constant heading towards the goal, birds will be drifted by crosswinds. (b) Compensation: Adjusting heading during flight to maintain a constant track towards the goal. From Richardson (1991). ............................ 29 Figure 1-4. Nightly change in seasonal proportion of migrants. Circular histograms show the tracks during the 6 peak-volume migration nights (A = 08-09 Sep; B = 17-18 Sep; C = 21-22 Sep; D = 01-02 Oct; E = 11-12 Oct; F = 18-19 Oct) with bins representing 15°. ρ represents the directional concentration of the night (1 = all migrants within one bin, and 0 = equal distribution among bins) See Appendix 3 for mean track bearing on each peak volume night. .................................................................................................................... 30 Figure 1-5. Map of Gulf of Maine and surrounding region. All data shown are from the 6 large-volume migration nights (see Figure 1-4). Circular histogram of headings, centered on Bon Portage Island. Asterisk indicates the mean projected landfall. Lines indicate projected landfall of 32% of migrants. Map project, lines and asterisk were computed using a North American equidistant conical projection.................................................... 31 Figure 1-6. Geometric mean numbers of tracks detected per hour over the entire season. ........................................................................................................................................... 32 Figure 1-7. Mean hourly tracks of migrants since sunset (a) and before sunrise (b)....... 32 Figure 1-8. Circular distribution of wind direction observed during the study. Bins represent 5.5° sections of the data. Length of each arm