Vowinckel, E.

English

University of Calgary Journal Hosting

450 REVIEWS FREEZING  LEVEL STATISTICS FOR CANADA. BY R. L. TITUS. Canada Depart- ment of Transport  Meteorological Branch, 1968. 8% x 11 inches, 40 pages. $1 S O ,  This  paper is number 12 in the very valu- able series of climatological studies published by the Meteorological Branch. Each one is the evaluation of a particular  meteorological parameter  for  Canada. The author gives statistical results of the evaluation of the freezing levels for Cana- dian radiosonde  stations since 1955. The main part of the publication is comprised of statistical tables and maps constructed from these values. The text gives a short  and clear description of the content of each  table  and the manner in which it was derived. Also a description of the method used for drawing the  charts is given. Information is given about the frequency of below zero temperatures above specified levels, temperatures above zero in specified levels, average thickness of surface  layers below zero with higher than zero tempera- tures  above and frequency of more  than  one freezing level. These data will prove  valuable for aviation climatology and an analysis of this wealth of information for a general climatology of Canada. E. Vowinckel RELATIONSHIPS IN THE CHARADRII (SHOREBIRDS): A TAXONOMIC  STUDY BASED ON COLOR PATTERNS OF THE DOWNY  YOUNG. BY JOSEPH R. JEHL, JR. San Diego: Society of Natural History,  Mem- oir 3,  1968. 8% x 11 inches. 54 pages, il- lustrated. $3.50. Dr. Jehl’s paper is a contribution to the understanding of relationships among  the higher taxonomic categories of the avian Suborder Charadrii, the  waders or shorebirds. Evaluations of relatedness are based on the topography of the dorsal  down  colors of the young. Specimens of 109 of the 201 wader species were examined, and use was made of descriptions or photographs of 53 more species. The median number of skins examin- ed per species was 3 (range 1-74). Dr. Jehl’s three seasons in the  Canadian breeding range of about  14  wader species has added much to the content of this work. The first few pages of this  monograph are largely a discussion of the rationale for using the color  pattern of downy  oung  as a taxonomic  character. It is argued that the character is “highly conservative” reflecting phylogenetic relationships. Two larger sec- tions constitute the main body of the study. The first describes the color pattern  for each Genus with the aid of diagrams and 62 photographs of museum specimens. The second section considers the relationships among shorebird Genera and Families (and Tribes  in  Tringinae) on  the basis of the down patterns and evaluates these in relation to existing taxonomies. Two short sections fol- low in which are presented an admittedly “highly speculative” shorebird phylogeny and a revised classification scheme. Finally,  a very useful Appendix lists many sources of de- scriptions of downy young  shorebirds. In the introductory sections of his study, Dr. Jehl lists reasons for his feeling the color pattern is a “highly conservative” character reflecting “phylogenetic relationships and not environmental differences.” Some of the arguments presented will not be compelling to every reader. Perhaps an equally strong case can  be made for considering down pat- terns as reflecting environmental differences and as considerably less than “highly con- servative.” For example, Dr. Jehl points out the following observations: a) Two species may have  similar or “identical” patterns and occupy different habitats. b) Young of species not closely related  have different patterns and may occupy the same habitat.  One is asked to accept the interpretation that such pattern similarities and differences are there- fore  not reflections of habitat similarities and differences. Surely this can only be argued from a  framework of relevant data,  and such data  are lacking in this study. It may be equally probable, for example, that the oc- currence of similar patterns  in different “habitats” reflects similarity in microhabitat features where the young birds forage and where they hide in response to predators. Particularly damaging is that  Dr.  Jehl (citing Cott, H. B. 1957. Adaptive  coloration  in animals. Methuen) states that “The color of young shorebirds seems strongly correlated with that of the substrate  in nesting areas . . . for this reason it is usually of little  taxonomic value.” Thus  the importance of the observa- tion that different patterns  occur  in  the  same habitat is considerably reduced because species whose chicks are quite differently colored also occur in the same habitat. My experience of two seasons in the Canadian north studying the  foraging ecology and nest site selection in 6 species of shorebirds sug- gests that the alternate hypothesis that pat- tern is correlated with substrate  and  therefore a reflection of microhabitat crypsis must be disproved before the usefulness of pattern as    taxonomic character can be fully evaluated. 

Freezing Level Statistics for Canada, by R.L. Titus

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Freezing Level Statistics for Canada, by R.L. Titus

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