Summary
Observations of the foraging behavior of six captive dark-eyed juncos (Junco hyemalis) are used to test the assumptions and predictions of optimal diet choice models (Pyke et al. 1977) that include nutrients (Pulliam 1975). The birds sequentially encountered single seeds of niger thistle (Guizotia abyssinica) and of canary grass (Phalaris canariensis) on an artificial substrate in the laboratory. Niger thistle seeds were preferred by all birds although their profitability in terms of energy intake (J/s) was less than the profitability of canary grass seeds. Of four nutritional components used to calculate profitabilities (mg/s) lipid content was the only characteristic that could explain the junco's seed preference. As predicted by optimal diet theory the probability of consuming niger thistle seeds was independent of seed abundance. However, the consumption of 71–84% rather than 100% of the seeds encountered is not consistent with the prediction of all-or-nothing selection. Canary grass seeds were consumed at a constant rate (no./s) independent of the number of seeds encountered. This consumption pattern invalidates a model that assumes strict maximization. However, it is consistent with the assumption that canary grass seeds contain a nutrient which is required in minimum amounts to meet physiological demands (Pulliam 1975). These experiments emphasize the importance of incorporating nutrients into optimal foraging models and of combining seed preference studies with studies of the metabolic requirements of consumers.
Similar content being viewed by others
References
Barnard CJ, Stephens H (1981) Prey size selection by lapwings in lapwing/gull associations. Behaviour 77:1–22
Blem CR (1976) Patterns of lipid storage and utilization in birds. Am Zool 16:671–684
Bliss CI (1970) Statistics in Biology, vol 2. McGraw-Hill Book Co, New York, pp 454–458
Carey C, Dawson WR, Maxwell LC, Faulkner JA (1978) Seasonal acclimatization to temperature in Cardueline finches II. Changes in body composition and mass in relation to season and acute cold stress. J Comp Physiol 125:101–114
Charnov EL (1976) Optimal foraging: attack strategy of a mantid. Am Nat 110:141–151
Conley JB, Blem CR (1978) Seed selection by japanese quail (Coturnix coturnix japonica). Am Midl Nat 100:135–140
Davies NB (1977a) Prey selection and social behaviour in wagtails (Aves: Motacillidae). J Anim Ecol 46:37–57
Davies NB (1977b) Prey selection and the search strategy of the spotted flycatcher (Muscicapa striata): a field study on optimal foraging. Anim Behav 25:1016–1033
Elner RW, Hughes RN (1978) Energy maximization in the diet of the shore crab, Carcinus maenas. J Anim Ecol 47:103–116
Goss-Custard JD (1977a) Optimal foraging and the size selection of worms by redshank (Tringa totanus) in the field. Anim Behav 25:10–29
Goss-Custard JD (1977b) Predator responses and prey mortality in the redshank (Tringa totanus) and a preferred prey, Corophium volutator. J Anim Ecol 46:21–35
Green R (1978) Factors affecting the diet of farmland skylarks (Alauda arvensis). J Anim Ecol 47:913–928
Kear J (1962) Food selection in finches with special references to interspecific differences. Proc Zool Soc Lond 138:163–204
Krebs JR, McCleery RH (1984) Optimization in behavioral ecology. In: Krebs JR, Davies NB (eds) Behavioural ecology: An evolutionary approach. Blackwell Scientific Publications, Boston Massachusetts
Krebs JR, Erichsen JT, Webber MI, Charnov EL (1977) Optimal prey selection in the great tit (Parus major). Anim Behav 25:30–38
Krebs JR, Stephens DW, Sutherland WJ (1983) Perspecitives in optimal foraging. In: Perspectives in ornithology. Am Ornith Union
MacArthur RH, Pianka ER (1966) On the optimal use of a patchy environment. Am Nat 100:603–609
McFarland DJ, Houston AI (1981) Quantitative ethology: The state space approach. Pitmann, London
Mittlebach GG (1981) Foraging efficiency and body size: a study of optimal diet and habitat use by bluegills. Ecology 62:1370–1386
Odum EP, Major JC (1956) The effect of diet on photoperiod induced lipid deposition in the white-throated sparrow. Condor 58:222–228
Pulliam HR (1974) On the theory of optimal diets. Am Nat 108:59–74
Pulliam HR (1975) Diet optimization with nutrient constraints. Am Nat 109:765–768
Pulliam HR (1980) Do chipping sparrows forage optimally? Ardea 68:75–82
Pyke GH (1984) Optimal foraging theory: a critical review. Ann Rev Ecol Syst 15:523–575
Pyke GH, Pulliam HR, Charnov EL (1977) Optimal foraging: a selective review of theory and tests. Q Rev Biol 52:137–154
Rapport DJ (1971) An optimization model of food selection. Am Nat 105:575–588
Rapport DJ (1980) Optimal foraging for complementary resources. Am Nat 116:324–346
Rechten C, Avery M, Stevens A (1983) Optimal prey selection: why do great tits show partial preferences? Anim Behav 31:576–584
Schoener TW (1971) Theory of feeding strategies. Ann Rev Ecol Syst 2:369–404
Schoener TW (1974) The compression hypothesis and temporal resource partitioning. Proc Nat Acad Sci 71:4169–4172
Sokal RR, Rohlf FJ (1969) Biometry. WH Freeman and Co, San Francisco
Willson MF (1971) Seed selection in some North American finches. Condor 73:415–429
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Thompson, D.B., Tomback, D.F., Cunningham, M.A. et al. Seed selection by dark-eyed juncos (Junco hyemalis): optimal foraging with nutrient constraints?. Oecologia 74, 106–111 (1987). https://doi.org/10.1007/BF00377353
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF00377353