22 BULLETIN 17 0, UNITED STATES NATIONAL MUSEUM 



Hawk from this nest in 1926, and in 1927 we had found it occupied by a Falcon 

 with five eggs. Going to it in 1928 we at first thought it deserted as no bird could 

 be seen, but, upon going directly beneath it and shouting, the Falcon flushed with 

 her customary fierce challenge. Much to our pleasure the nest contained five 

 eggs of the Falcon and, to our great surprise, one egg of the Red-tail, all of which 

 were perfectly fresh. The poor Hawks had been through a very hard spring, as 

 they had built a nest about half a mile distant across the river and had their eggs 

 eaten by Ravens. Of course we had no means of ascertaining the course of events, 

 but it would have been most interesting to know if the Hawk had laid its egg before 

 or after the Falcons had taken possession of the nest. It is highly probable that 

 the Falcons could and would drive away the rightful owner, if they wished to do so, 

 even though the Hawks had taken possession first. However, on the other hand, 

 it seems highly possible that the Ravens had destroyed an incomplete set in the 

 new nest and the Hawk had then taken advantage of a temporary absence of the 

 Falcons and laid the egg to complete her set in her nest of a former year. 



The friendly relationship existing between Falcons and Ravens, that are both 

 nesting in the same cliff, is nothing short of astounding, especially when we consider 

 that a Raven is perhaps the most "dyed-in-the-wool" egg eater in the animal 

 kingdom. It is fairly safe to say that in seven cases out of ten a pair of Ravens 

 will be nesting in the same cliff that is occupied by a pair of Falcons, the nests in 

 many cases being only a few hundred feet apart. Yet strangely enough we have 

 never seen a sign of friction of any kind existing between the two species. When 

 we first commenced our studies of these birds we always were fearful that the 

 Ravens would eat the Falcon eggs before the set was complete. However, this 

 has never occurred in all the many instances that have come under our observa- 

 tion, the Falcons paying little or no attention to the Ravens at any time. The 

 reason for this may, perhaps, date back to some past generations of the Ravens 

 who learned through bitter experience that it was far the wisest thing to make 

 the contents of a Falcon nest the exception to their general rule of eating eggs and 

 baby birds. Perhaps this knowledge has been inherited by the present generations. 

 One thing absolutely certain is that the Falcons "rule the roost" and do exactly 

 as they please in the selection of nests, the poor Ravens simply taking what the 

 Falcons do not want and making the best of things. As a rule the Ravens lay their 

 eggs about a week earlier than the Falcons, but the latter have apparently already 

 selected the nest they want and the Ravens usually build a new nest for their first 

 set. If the contents of the nests of both species are removed the}' will usually lay 

 again in the same nests, but they occasionally trade nests * * *. Yet in all 

 this switching around we have never seen any signs of discord between the two 

 species, trying as it must be on their tempers. 



John G. Tyler (1923) says: 



In the region where my observations have been made the north end of the ridges 

 breaks off abruptly into cliffs and for that reason most of the nests I have examined 

 have had a northern exposure. A few have been on west-facing cliffs and one 

 faced the east or northeast, but none has been on ledges with an outlook to the 

 south. Of seventeen nests personally examined during the past few years nine 

 have been in pot holes of various sizes, where the eggs rested on the gravel and 

 small loose rocks which lined the cavity. Six sets were laid on the tops of nests 

 built by ravens and these nests were utilized without any alterations whatever. 

 In one case, the nest was newly built and freshly lined with wool, while the other 

 five were in various stages of disrepair. One pair of falcons used, during three 

 seasons, a hole in which a pair of ravens had evidently built a nest many years 

 before. 



