Volume 51, No. 1

Search by author or title:

Laying sequence and oceanographic factors affect egg size in Scripps's Murrelets Synthliboramphus scrippsi at Santa Barbara Island


1School of Environmental and Forest Sciences, University of Washington 98195, Seattle, Washington, USA (
2Washington Cooperative Fish and Wildlife Research Unit, School of Aquatic and Fishery Sciences, University of Washington, Seattle, Washington 98195, USA
3California Institute of Environmental Studies, Davis, California 95617, USA
4Channel Islands National Park, Ventura, California 93001, USA
5U.S. Geological Survey, Washington Cooperative Fish and Wildlife Research Unit, School of Environmental and Forest Sciences & School of Aquatic and Fishery Sciences, University of Washington, Seattle, Washington 98195, USA


TODD ZARAGOZA, M.I., DuVALL, A.J., HOWARD, J.A., MAZURKIEWICZ, D.M. & CONVERSE, S.J. 2023. Laying sequence and oceanographic factors affect egg size in Scripps's Murrelets Synthliboramphus scrippsi at Santa Barbara Island. Marine Ornithology 51: 1 - 9

Received 30 December 2021, accepted 01 September 2022

Date Published: 2023/04/15
Date Online: 2023/04/10
Key words: Alcidae, egg size, laying sequence, index, ocean productivity, monitoring


Egg size is an important avian life history parameter, with larger eggs indicating greater investment of resources in the chick. Prey availability can affect such investment. We investigated the effects of oceanographic conditions and laying sequence on Scripps's Murrelet Synthliboramphus scrippsi egg size at Santa Barbara Island, California during 2009-2017. We evaluated oceanographic covariates characterizing marine productivity for their effect on egg size, including large-scale oceanographic indices such as the Pacific Decadal Oscillation (PDO) index, Oceanic Niño Index (ONI), and North Pacific Gyre Oscillation (NPGO) index. We also evaluated a larval anchovy catch-per-unit-effort (ANCHL) index and the Biologically Effective Upwelling Transport Index (BEUTI) as region-wide indices, and sea surface temperature (SST) as a local index. We evaluated oceanographic conditions over the entire year and during the breeding season only. We also considered the contribution of lagged effects to oceanographic conditions. Our results generally ran counter to our hypothesis that increased ocean productivity should increase egg size. Based on Akaike's Information Criterion, the four top-ranked models provided support for an association between larger eggs and conditions indicative of lower oceanographic productivity, including lower values of BEUTI and NPGO, and higher values of ONI, PDO, and SST. The only result that supported our hypothesis was a positive relationship between ANCHL and egg size, although the 95% confidence interval for the effect included 0. The strongest relationship detected was between laying sequence and egg size, as second eggs were considerably larger than first eggs. Our results indicate substantial complexity in the relationship between ocean productivity and seabird demography. A better understanding of how ocean productivity affects seabird breeding outcomes through multiple mechanisms will help improve predictions of how seabirds will respond to changing ocean conditions.


AINLEY, D.G., BOEKELHEIDE, B.J., MORRELL, S.H. & STRONG, C.S. 1990. Cassin's Auklet. In: AINLEY, D.G. & BOEKELHEIDE, B.J. (Eds.) Seabirds of the Farallon Islands: Dynamics of an Upwelling System Community. Stanford, USA: Stanford University Press, pp. 306-338.

AINLEY, D.G. & HYRENBACH, K.D. 2010. Top-down and bottom-up factors affecting seabird population trends in the California current system (1985-2006). Progress in Oceanography 84: 242-254.

AINLEY, D.G., SYDEMAN, W.J. & NORTON, J. 1995. Upper-trophic level predators indicate interannual negative and positive anomalies in the California Current food web. Marine Ecology Progress Series 118: 69-79.

Anderson D.W., Gress, F. & Kelly, P.R. 1980. Brown Pelicans as anchovy stock indicators and their relationships to commercial fishing. California Cooperative Oceanic Fishery Investigations, Reports 21: 54-61.

Astheimer, L.B. 1985. Long laying intervals: A possible mechanism and its implications. The Auk 102: 401-409. doi:10.2307/4086789

BAKUN, A., BLACK, B.A., BOGRAD, S.J. ET AL. 2015. Anticipated effects of climate change on coastal upwelling ecosystems. Current Climate Change Reports 1: 85-93. doi:10.1007/s40641-015-0008-4

BARRETT, R., NILSEN, E. & ANKER-NILSSEN, T. 2012. Long-term decline in egg size of Atlantic Puffins Fratercula arctica is related to changes in forage fish stocks and climate conditions. Marine Ecology Progress Series 457: 1-10. doi:10.3354/meps09813

BATES, D., MÄCHLER, M., BOLKER, B. & WALKER, S. 2015. Fitting linear mixed-effects models using lme4. Journal of Statistical Software 67: 1-48. doi:10.18637/jss.v067.i01

BENNETT, J.L., JAMIESON, E.G., RONCONI, R.A. & WONG, S.N.P. 2017. Variability in egg size and population declines of Herring Gulls in relation to fisheries and climate conditions. Avian Conservation and Ecology 12: 16. doi:10.5751/ACE-01118-120216

BOGRAD, S.J. & LYNN, R.J. 2001. Physical-biological coupling in the California Current during the 1997-99 El Niño-La Niña Cycle. Geophysical Research Letters 28: 275-278. doi:10.1029/2000GL012047

BRADY, R.X., ALEXANDER, M.A., LOVENDUSKI, N.S. & RYKACZEWSKI, R.R. 2017. Emergent anthropogenic trends in California Current upwelling. Geophysical Research Letters 44: 5044-5052. doi:10.1002/2017GL072945

CARTER, H.R., MCCHESNEY, G.J., JAQUES, D.L. ET AL. 1992. Breeding populations of seabirds in California, 1989-1991, volume 1 population estimates. Dixon, USA: US Fish and Wildlife Service, Northern Prairie Wildlife Research Center; Newark, USA: US Fish and Wildlife Service San Francisco Bay National Wildlife Complex.

CHAVEZ, F.P., RYAN, J., LLUCH-COTA, S.E. & NIQUEN C., M. 2003. From anchovies to sardines and back: Multidecadal change in the Pacific Ocean. Science 299: 217-221. doi:10.1126/science.1075880

Checkley, D.M., Asch, R.G. & Rykaczewski, R.R. 2017. Climate, anchovy, and sardine. Annual Review of Marine Science 9: 8.1-8.25.

CHECKLEY, D.M. & BARTH, J.A. 2009. Patterns and processes in the California Current System. Progress in Oceanography 83: 49-64. doi:10.1016/j.pocean.2009.07.028

CHENILLAT, F., RIVIÈRE, P., CAPET, X., LORENZO, E.D. & BLANKE, B. 2012. North Pacific Gyre Oscillation modulates seasonal timing and ecosystem functioning in the California Current upwelling system. Geophysical Research Letters 39: L01606. doi:10.1029/2011GL049966

CLIMATE PREDICTION CENTER INTERNET TEAM. Cold & Warm Episodes by Season. College Park, USA: National Weather Service. [Accessed at on 15 July 2021.]

FIEDLER, P.C., METHOT, R.D. & HEWITT, R.P. 1986. Effects of California El Niño 1982-1984 on the northern anchovy. Journal of Marine Research 44: 317-338. doi:10.1357/002224086788405365

GOODMAN, D. 1974. Natural selection and a cost ceiling on reproductive effort. American Naturalist 108: 247-268.

GJERDRUM, C., VALLÉE, A.M.J., CLAIR, C.C.S., BERTRAM, D.F., RYDER, J.L. & BLACKBURN, G.S. 2003. Tufted Puffin reproduction reveals ocean climate variability. Proceedings of the National Academy of Sciences 100: 9377-9382. doi:10.1073/pnas.1133383100

HAMILTON, C.D., CARTER, H.R. & GOLIGHTLY, R.T. 2004. Diet of Xantus's Murrelets in the Southern California Bight. The Wilson Bulletin 116: 152-157.

HAMILTON, C.D., GOLIGHTLY, R.T. & TAKEKAWA, J.Y. 2011. Relationships between breeding status, social-congregation attendance, and foraging distance of Xantus's Murrelets. The Condor 113: 140-149. doi:10.1525/cond.2011.100040

HIPFNER, J.M. 2008. Matches and mismatches: Ocean climate, prey phenology and breeding success in a zooplanktivorous seabird. Marine Ecology Progress Series 368: 295-304. doi:10.3354/meps07603

HIPFNER, J.M. 2012. Effects of sea-surface temperature on egg size and clutch size in the Glaucous-winged Gull. Waterbirds 35: 430-436. doi:10.1675/063.035.0307

HUNT, G.L. JR. & J.L. BUTLER. 1980. Reproductive ecology of Western Gulls and Xantus's Murrelets with respect to food resources in the Southern California Bight. California Cooperative Oceanic Fisheries Investigation, Reports 21: 62-67.

JACOX, M.G., EDWARDS, C.A., HAZEN, E.L. & BOGRAD, S.J. 2018. Coastal upwelling revisited: Ekman, Bakun, and improved upwelling indices for the U.S. West Coast. Journal of Geophysical Research: Oceans 123: 7332-7350. doi:10.1029/2018JC014187

JACOX, M.G., HAZEN, E.L. & BOGRAD, S.J. 2016. Optimal environmental conditions and anomalous ecosystem responses: Constraining bottom-up controls of phytoplankton biomass in the California Current System. Scientific Reports 6: 27612. doi:10.1038/srep27612

KARNOVSKY, N.J., SPEAR, L.B., CARTER, H.R. ET AL. 2005. At-sea distribution, abundance and habitat affinities of Xantus's Murrelets. Marine Ornithology 33: 89-104.

KRIST, M. 2011. Egg size and offspring quality: A meta-analysis in birds. Biological Reviews of the Cambridge Philosophical Society 86: 692-716. doi:10.1111/j.1469-185X.2010.00166.x

LEE, D.E., WARZYBOK, P.M. & BRADLEY, R.W. 2012. Recruitment of Cassin's Auklet (Ptychoramphus aleuticus): Individual age and parental age effects. The Auk 129: 124-132. doi:10.1525/auk.2012.10224

LORENZO, E.D., SCHNEIDER, N., COBB, K.M., ET AL. 2008. North Pacific Gyre Oscillation links ocean climate and ecosystem change. Geophysical Research Letters 35: L08607. doi:10.1029/2007GL032838

MacCall, A.D., Sydeman, W.J., Davison, P.C. & Thayer, J.A. 2016. Recent collapse of northern anchovy biomass off California. Fisheries Research 175: 87-94. doi:10.1016/j.fishres.2015.11.013

MARCHISIO, N., BARRIONUEVO, M. & FRERE, E. 2021. Compensatory effect of egg size dimorphism on hatching asynchrony in Magellanic Penguin. Journal of Avian Biology 52: 1-11. doi:10.1111/jav.02673

MURRAY, K.G., WINNETT-MURRAY, K. & HUNT, G.L. 1980. Egg neglect in Xantus' Murrelet. Proceedings of the Colonial Waterbird Group 3: 186-195.

MURRAY, K.G., WINNETT-MURRAY, K., EPPLEY, Z.A. & SCHWARTZ, D.B. 1983. Breeding biology of the Xantus' Murrelet. The Condor 85: 12-21. doi:10.2307/1367880

NAGER, R. 2006. The challenges of making eggs. Ardea-Wageningen 94: 323-346.

NOAA [National Oceanic and Atmospheric Association]. California Current Integrated Ecosystem Assessment website. Washington, USA. [Accessed at on 05 September 2021.]

POZO BUIL, M., JACOX, M.G., FIECHTER, J. ET AL. 2021. A dynamically downscaled ensemble of future projections for the California Current System. Frontiers in Marine Science 8: 612874. doi:10.3389/fmars.2021.612874

R CORE TEAM. 2021. R: A Language and Environment for Statistical Computing. Vienna, Austria: The R Foundation for Statistical Computing. [Accessed at on 01 June 2021.]

ROBBINS, C.T. 1981. Estimation of the relative protein cost of reproduction in birds. The Condor 83: 177-179. doi:10.2307/1367424

ROTH, J.E., SYDEMAN, W.J. & MARTIN, P.L. 2005. Xantus's Murrelet breeding relative to prey abundance and oceanographic conditions in the Southern California Bight. Marine Ornithology 33: 115-121.

SCHAFFNER, F.C. 1986. Trends in Elegant Tern and northern anchovy populations in California. Ornithological Applications 88: 347-354. doi:10.2307/1368882

SCHEIPL, F., GREVEN, S. & KÜCHENHOFF, H. 2008. Size and power of tests for a zero random effect variance or polynomial regression in additive and linear mixed models. Computational Statistics & Data Analysis 52: 3283-3299. doi:10.1016/j.csda.2007.10.022

SEALY, S.G. 1975. Egg size of murrelets. The Condor 77: 500. doi:10.2307/1366104

Siple, M.C., Essington, T.E., Barnett, L.A.K. & Scheuerell, M.D. 2020. Limited evidence for sardine and anchovy asynchrony: Re-examining an old story. Proceedings of the Royal Society B 287: 20192781. doi:10.1098/rspb.2019.2781

Sorensen, M.C., Hipfner, J.M., Kyser, T.K. & Norris, D.R. 2009. Carry-over effects in a Pacific seabird: Stable isotope evidence that pre-breeding diet quality influences reproductive success. Journal of Animal Ecology 78: 460-467. doi:10.1111/j.1365-2656.2008.01492.x

Stein, R.W. & Williams, T.D. 2013. Extreme intraclutch egg-size dimorphism in Eudyptes penguins, an evolutionary response to clutch-size maladaptation. The American Naturalist 182: 260-270. doi:10.1086/670929

Sydeman, W.J., Dedman, S., García-Reyes, M., et al. 2020. Sixty-five years of northern anchovy population studies in the southern California Current: A review and suggestion for sensible management. ICES Journal of Marine Science 77: 486-499. doi:10.1093/icesjms/fsaa004

THOMSEN, S.K. & GREEN, D.J. 2019. Predator‐mediated effects of severe drought associated with poor reproductive success of a seabird in a cross‐ecosystem cascade. Global Change Biology 25: 1642-1652. doi:10.1111/gcb.14595

THORNE, L.H., HAZEN, E.L., BOGRAD, S.J. ET AL. 2015. Foraging behavior links climate variability and reproduction in North Pacific albatrosses. Movement Ecology 3: 27. doi:10.1186/s40462-015-0050-9

WEN, C., KUMAR, A. & XUE, Y. 2014. Factors contributing to uncertainty in Pacific Decadal Oscillation index. Geophysical Research Letters 41: 7980-7986. doi:10.1002/2014gl061992

WHITWORTH, D.L., TAKEKAWA, J.Y., CARTER, H.R., NEWMAN, S.H., KEENEY, T.W. & KELLY, P.R. 1995. Foraging Distribution and Post-Breeding Dispersal of the Xantus' Murrelets in the Southern California Bight. Unpublished report. Vallejo and Dixon, USA: National Biological Service and California Pacific Science Center; Point Mugu, USA: Naval Air Weapons Station.

WILLIAMS, T.D. 2005. Mechanisms underlying the costs of egg production. BioScience 55: 39-48. doi:10.1641/0006-3568(2005)055[0039:MUTCOE]2.0.CO;2

Search by author or title:

Browse previous volumes: