1. Baillie SR, Rehfisch MM (eds) (2006) National and site-based alert systems for UK birds. BTO Research Report No. 226. British Trust for Ornithology, Thetford
2. Barker RJ, Sauer JR (1992) Modeling population change from time series data. In: McCullough DR, Barrett RH (eds) Wildlife 2001: populations. Elsevier, New York, pp 182–194
3. Demerdzhiev D, Horváth M, Kovács A, Stoychev S, Karyakin I (2011) Status and population trend of the Eastern Imperial Eagle (Aquila heliaca) in Europe in the period 2000–2010. Acta Zool Bulg Suppl 3:5–14
4. Drew GS, Piatt JF, Bodkin JL (2007) Population status and trends of marine birds and mammals in Glacier Bay National Park. In: Piatt JR, Gende SM (eds) Proceedings of the fourth glacier bay science symposium. United States Geological Survey, Washington DC, pp 129–132
5. Faaborg J, Dugger KM, Arendt WJ, Woodworth BL, Baltz ME (1997) Population declines of the Puerto Rican vireo in Guánica forest. Wilson Bull 109:195–202