weather, except possibly the amount of sunshine. 

 They have tended to nest earher in cloudy winters. 

 No correlation with food supply has been found, 

 but the possible effects are not discounted (Tan- 

 ner 1942). 



According to Mcllhenny in Bendire (1895), 

 the female does all work of excavating the nesting 

 cavity, but Audubon (1842) states that both birds 

 work at excavating. Thompson (1896) also re- 

 ports that both sexes excavate. 



Although Bendire (1895) said there were 5 

 eggs per clutch and only 1 brood per season, 

 Arthur Allen in Bent (1939) found the number of 

 eggs normally not more than 3, and 1 or 2 of 

 those often infertile. Frequently, if nesting is suc- 

 cessful at all, it results in a single young rather 

 than 2 or3. Tanner (1942) figures that the average 

 number of eggs per set is 2.9 with a range of 1 to 

 4, and that early nests had fewer eggs than later 

 ones. He said the period of incubation and length 

 of time young stay in the nest is unknown. In the 

 Singer Tract, the male incubated every night and 

 the female most of the time during the day. They 

 exchanged places about eight times a day, with 

 no regularity in the setting time except when the 

 female relieved the male in the morning and just 

 before he took his place for the night. Both sexes 

 share about equally in feeding the young in the 

 nest and for a while after they leave the nest. Young 

 follow parents on feeding trips and gradually 

 learn to obtain food for themselves after about 4 

 weeks, but still receive food from adults after 2 to 

 2.5 months (Tanner 1942). Hoyt (1905) states 

 that after young leave the nest in April, they re- 

 main with their parents until the mating season in 

 December. Some young stay with parents even 

 after another family is fledged the following nest- 

 ing season. All aggregations of ivory-bills are 

 probably family groups of one or more years pro- 

 duction. Tanner (1942) says the average number 

 of young per brood leaving the nest is 2.11 with 

 a survival success of 50%. He says there is no data 

 on survival of young to breeding age nor length of 

 time an adult can live and successfully breed. The 

 important difference between nesting of ivory- 

 bills and other species is that it lays fewer eggs. A 

 pair may go through a season without any attempt 

 at nesting. It probably takes at least 2 years to 

 reach breeding age. Possibly the quantity of food 

 or lack of synchronization of the reproductive 

 cycles of a mated pair may determine whether 

 nesting will occur. The lower rate of reproduction 



accentuates the danger inherent in the small size 

 of the population. The most likely serious preda- 

 tors on nesting ivory-bills are barred owls, rac- 

 coons, and nest mites. 



Ivory-bill pairs usually nest well separated 

 from each other (about 4.8 km apart in the Singer 

 Tract), and, at least occasionally, nest in the same 

 area year after year. There are no records of birds 

 protecting territory from trespass by another 

 ivory-bill (Tanner 1942). 



C. p. bairdii. Incubation is shared by both 

 sexes (Dennis 1948). Feeding and brooding are 

 thought to be shared by both sexes (Lamb 1957). 

 Causes of nesting failure are always traceable to 

 human interference, although crows are thought 

 by natives to be predators on nests (Lamb 1957). 



MANAGEMENT AND CONSERVATION 



C. p. principalis. The only way of preserving 

 the ivory-billed woodpecker is to preserve in their 

 entirety any areas that can be found where the 

 birds still exist. A suitable area would be about 

 6 to 8 km^ of good habitat for each pair. Pos- 

 sibly some timber may be selectively cut, leaving 

 dead and dying trees. The quantity of food may 

 be artificially increased by progressively killing 

 enough trees at a time to supply a large number 

 of wood-boring insect larvae (Tanner 1942, 

 Paul Sykes in lit. 1968). Dennis (1967) found 

 that trees killed by girdling do not attract as 

 many wood-boring insects as those killed by 

 flooding and suggested limited inundation and 

 cutting of pine slash as a means of increasing 

 ivory -bill food supply. 



In October 1974, a bill was passed by Congress 

 creating a preserve of 34,000 ha of potential 

 ivory-bill habitat in the Big Thicket area of 

 southeastern Texas (Dennis ms. 1976). 



Public information is an important part of 

 ivory-bill management as with other endangered 

 species. Only an interested and sympathetic public 

 can save the bird from such threats as big dams, 

 wholesale clearing of bottomland timber, and 

 drainage of favorable habitat (Dennis 1967). 



In 1967, the U.S. Corps of Engineers halted 

 the timber management plan at Dam B Reservoir 

 on Neches River, Texas, in deference to ivory- 

 bills. Federal and state wardens in area were alerted 

 and public appeal received positive and gratifying 

 response (Harry Goodwin in lit. to Roland Cle- 

 ment 19 December 1967). 



