BALD HILLS PRAIRIES RAPTOR SURVEY IN REDWOOD NATIONAL PARK 2013 ANNUAL REPORT

Schmidt, Kristin

Raptor surveys throughout the Bald Hills in Redwood National Park (“the park”) began in December of 1998. Originally, the surveys were ancillary to a study designed to determine effects of prescribed fire on small mammal and reptile populations in coastal prairie grasslands in the park. Though the small mammal/reptile study was discontinued after the 2001 field season, raptor surveys continued in each year through the present and results have been reported annually. Eleven surveys were conducted in 2013; no surveys took place in the month of October. The total number of raptor observations in 2013 was 122, consisting of 178 individuals. The number of observations was up substantially from last year’s number (107) and also was substantially higher than the number of observations in 2008 (91), the high for the 4-year period between 2006-2009. The number of individuals counted was equal to that of last year, and comparable to the number recorded in 2010 (170). Two relatively large groups of ravens contributed to the number of individuals observed for that species. The highest number of raptor observations in 2013 was in Coyote Creek Prairie (29). This is similar to the numbers recorded in 2010-2012. Childs Hill Prairie was once again in second place (21) for overall numbers after falling short in 2012. In the lower group of prairies (Ganns, Elk Camp, and Dolason) there were 16 observations (13%), and in the middle prairies (Airstrip, Counts Hill, Maneze, Childs Hill, and Williams Ridge) there were 57 observations (47%). The upper prairies (Copper Creek, Coyote Creek, Schoolhouse and Eastside) accounted for 49 observations (40%). There were no raptor observations in Wooden Gate Prairie in 2013. Differences in numbers of observations between the lower prairies, versus the middle and upper prairies, likely equate to the differences in area among the prairies; with grassland area progressively increasing eastward. There were 3 observations in Ganns, the smallest, and lowest elevation prairie, in 2013. For the second consecutive year, common ravens accounted for the highest number of individuals recorded, at 96, only 9 fewer than the 105 detected in 2012. However, the highest number of a species observations, were red-tailed hawks with 51 observations, compared to 44 observations of ravens. Red-tailed hawk and raven observations were followed by American kestrel (see table below). These 3 species have consistently been the most numerous of the surveys. Northern harriers were again the 4th most commonly observed species, with just 4 observations of 4 individuals. For the second year species not detected, compared to 2011, were merlin, white-tailed kite, American crow, and peregrine falcon. No mammalian carnivores were observed in the prairies in 2013. Numbers of individuals of all species recorded in 2013, compared with those from 2010, 2011, 2012, and the previous 4-year and 3-year periods are listed in the table below (from Sakai et al., 2000a, 2000b, and 2001; Sakai 2002, 2003, 2004, 2005; Schmidt 2010; NPS 2011, 2012, and 2013). It is probable that some of the records represent the same individual observed in different surveys, due to the territorial nature of most hawks, however, except in rare cases there is no way of determining if the birds are the same or different individuals.