Nesting Cycle 



The nesting cycle of most terrestrial species may be divided into six phases 

 (Black 1976): 



1 . Prenesting 



2. Nest building 



3. Egg laying 



4. Incubation (brooding) 



5. Nestling 



6. Fledgling 



Prenesting is the period between arrival on the breeding grounds and the 

 beginning of nest construction. Pair formation, pair bond maintenance, and 

 nest site selection take place during prenesting. 



Nest building may take up to a week for most passerines. Eggs are usually 

 laid at a rate of one per day, with incubation beginning after the last egg is 

 laid. High energy demands are placed on the female during the egg laying 

 period. 



Brooding (incubation) keeps eggs at their optimal temperature and, to a lesser 

 extent, provides a suitable humidity. Incubation for most small passerines 

 lasts 12 to 14 days. Hole nesters incubate about 2 days longer than other 

 small passerines (Welty 1975). 



The nestling stage lasts 12 to 13 days. Energy demands again increase for 

 both male and female as they feed the nestlings. Disturbance of nests after 

 the 7th or 8th day of the nestling stage often results in premature fledging 

 and subsequent loss of all or part of the brood. 



Fledglings are under parental care for the next 10 to 12 days. These figures 

 are average figures for small (warbler size) passerines and vary for 

 individual species. Generally larger birds take longer for each phase. 



FACTORS AFFECTING DISTRIBUTION AND ABUNDANCE 



Natural factors affecting the distribution and abundance of terrestrial bird 

 populations include habitat availability, competition, predation, disease, and 

 weather. The abundance of suitable habitat is the most important factor 

 affecting bird distribution. Unless disturbed, terrestrial habitats in 

 coastal Maine eventually become forested (see chapter 9, "The Forest System"). 

 Palustrine sites also fill with sediment and organic matter and become 

 forests, but this is a much longer process than on upland sites (see chapter 

 8, "The Palustrine System"). Natural factors returning forests to early 

 successional stages include wind storms and fire, but people are the most 

 influential force affecting land use patterns in coastal Maine. 



Competition for nest sites, food supply, roosting sites, and song perches 

 limit the population size of some species. Territoriality is an intrinsic 

 spacing mechanism for most species of terrestrial birds, and tends to reduce 

 intraspecific competition for food and nesting sites. Competition between 

 species is avoided by slight differences in habitat preference, food habits, 

 feeding behavior, or preferred feeding heights. 



16-27 



10-80 



