Study finds 70% decrease in the seabird population since 1950s


Compiling a global database of seabird population size records from English language literature, researchers at the University of British Columbia monitored 513 seabird populations (of total 3 213) and concluded that the monitored seabird populations of our world have dropped overall by 69.3% percent between 1950 and 2010. 

Seabirds have a great impact on the marine ecosystems and are therefore well monitored. The changes in their population are good indicators of long-term and large scale changes in marine ecosystems. These populations are now heavily influenced by threats like entanglement in fishing gear, over fishing of food sources, climate change, pollution, disturbance, direct exploitation, development, energy production, and introduced species (predators such as rats and cats introduced to breeding islands that were historically free of land-based predators). 

Analysis of global seabird population is limited to small spatial and temporal scales. The only global assessment of seabird population status, based on extinction risk as assessed by the IUCN Red List of Threatened Species, indicates that one third of seabird species are threatened with extinction, one half are known or suspected to be in decline, and at least four species are extinct

To estimate the overall global population trend from a large collection of time-series for different seabird populations, the researchers used multivariate autoregressive state-space (MARSS) modeling because it estimates population size based on time-series containing missing data, and estimates observation error (difference between actual and observed population size) and process error (year to year variability in population growth). MARSS models provide an estimate of the population size in the years when no survey was conducted. A MARSS model is described by the following equations, taken from Holmes et al 2012.

xt = xt-1+u+wt,  where wt~MVN (0,Qt)                          (1)

yt = xt+a+vt, where vt~MVN (0,Rt)                               (2)

In the Eqs 1 and 2, x is a m*T matrix representing the state of the random variable Xt at each time t. The parameter w is a m*T matrix of the process errors at time t, with a mean 0 and covariance matrix Qt. Parameter y represents a n*T matrix of the observation, some of which may be missing. v is a n*T column vector of the non-process errors, the observation errors at tand multivariate and normal with mean 0, and covariance matrix Rt. u and a are parameters.

As each of the seabird populations was reproductively and often geographically isolated, the researchers assumed they had independent random errors (diagonal Q matrix) and had different population parameters (u and a). As the population census data were collected by different groups utilizing different techniques (even within the same population), and some species are easier to detect than others, the researchers stipulated independent observation variances for each population (diagonal and unequal R matrix). However, much of the variation in process error may be the result of environmental, rather than demographic stochasticity, meaning that populations may show similar trends and the assumption of independent process error is invalid. The researchers calculated the size of Q and R as a proportion of u and a.

9 920 records for 3 213 breeding populations were compiled. The number of records per population ranged from one to forty-nine and averaged three. The records were unevenly distributed throughout the decades and most numerous in the 1980s and 1990s.

Number of records (annual and cumulative) in the global seabird population database, 1950–2010. Credit:Michelle Paleczny et al.

When Q and R matrices were set as diagonal and unequal (independent process and non-process errors used for each population), MARSS modeling revealed a substantial decline in seabird populations between 1950 and 2010. Compared to that in the year 1950, only 30% was left in the monitored portion of the seabird populations. On an average, each population lost a considerable number of individuals each year. 

“We expected to find that seabird populations are declining, but we didn’t necessarily expect to find a decline of this magnitude,” says Michelle Paleczny, the lead author of the paper. “In order to secure a future for seabirds, it’s going to be very important for us to increase the emphasis on efforts to conserve them.”

A substantial proportion of the seabird loss was due to large declines in the five most abundant populations, all located in the southern hemisphere. Between them, the populations of Sooty Terns (Sternidae) from French Polynesia and South Orkney, the South Sandwich Island populations of both Soft-plumaged Petrels and Kerguelen Petrels (both Procellariidae), and the Peruvian population of Guanay Cormorants (Phalacrocoracidae) accounted for over 30% of the total numbers of seabirds in the sampled population in 1950; all of these populations were reduced to less than 5% of their initial size by 2010. The populations that were found to increase tended to be small coastal populations. 

Population trend, 1950–2010, of the world’s monitored seabirds, estimated by multivariate autoregressive state-space (MARSS) modeling. Credit:Michelle Paleczny et al.

Because most of these threats pertain to seabirds all over the world, and because the study included such a variety of species, the researchers suspect that their findings are applicable to the entire global population.  Human activities have been continuously threatening the existence of seabird populations. No significant climatic oscillation was found to pose potential threats. In the end, it is high time we undertook conservation and restorative actions for seabird populations.


"Population Trend of the World’s Monitored Seabirds, 1950-2010" –  Michelle Paleczny, Edd Hammill, Vasiliki Karpouzi, Daniel Pauly – Published: June 9, 2015 – PLOS ONE – DOI: 10.1371/journal.pone.0129342​ (open access)

Featured credit: Birds in the sky by Susanne Nilsson (CC – Flickr)

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  1. How many dead birds since radiation from Japan’s nuclear crisis blanketed the air and Stratosphere with radiation?

    I direct you to this headline at Enenews dot com and check out Enenews for much more:

    “Former Japan TV News Anchor: The mutations have begun in Fukushima, birds found blind, unable to fly — Magazine: “Birds in tailspin 4 years after Fukushima… the proverbial canary in a coalmine” — Professor: Birds with mutations popping up all over in contaminated areas “

    1. Thanks for this link Ana, looks like a good one. You are right on this issue but unfortunately there are many other factors negatively effecting our world environment today in addition to this from Fukushima.
      To stay on your topic I first want to add to it then explain the “additions”. I have heard from some in Hawaii saying similar to what you say and the enenews reports coming from Japan’s meltdown. In Hawaii they are getting sea turtles washing up on shore with huge tumors on them and authorities are telling people not to touch them. The woman also told me that their water is contaminated, people are turning purple from the sun, their volcano’s are blowing and they are having almost daily earthquakes now too. She said she is “scared in Hawaii”.
      Not sure if you have heard, but across the USA tests are coming back showing high amounts of other forms of radiation & dangerous chems in our ground soils and water ways. We all come to this site obviously because we are aware of on going Earth events very out of the ordinary that the masses do not have a clue about as main stream news doesn’t report it. So due to this fact of life with our Earth, we have insanity in leadership that thinks it can play God and some how control a planet from doing what it does to cleanse and nourish itself naturally.
      That is one big “addition” element. In case you are not familiar, let me introduce you to ‘Geo-Engineering’ to “save” the planet from global warming/climate change. Did you know? This program has many remedies to it but the most prevalent one is called SRM – solar radiation management – dimming of the sun via planes with gigantic spraying nozzles on them flying through the atmosphere at different altitudes spraying chems to cool, dim the sun, create snow, and move systems to make rain. Weather modification.

      This ‘experiment’ out of panic is contributing to the melt down of our environment immensely. It is an eco collapse of proportions never known to man kind before. Dubbed a possible extinction event. We are encapsulated in an enormous cloud of geo spray haze in the atmosphere compliments of chem trails globally. Did you know? White skies are not normal, neither are lines in the sky or grid patterns, the skies are supposed to be deep blue with puffy white clouds and when was the last time you saw any of that?
      Here’s a link for you now – geoengineeringwatch.org
      Hawaii is not alone in it’s rumbles and ruptures, something is very wrong and the fact we are being sprayed to combat this warming issue says real trouble too. They can not control or stop any of it and it is a complete disaster situation globally. I have heard Fukushima is still leaking. Japan gets quakes almost every day, so how can they possibly keep things solid and running normally? Of course they are still leaking if you know truth you know this too. There are many many other lands doing these same things and no one reports this stuff, big cover up. Think about it and connect the dots. This link I gave you has very good info. on ingredients in this spray program but they imply man is causing this for weather wars, man made quakes too and that part is wrong so just a heads up with that. It is impossible for that to be true due to the consistency, amounts and depths of all the earthquakes happening globally every day now. NOT man made. For this to be so there would have to be people on a pc 24/7 zapping nations and causing them to have quakes – LOL.. not even enough time in between all these quakes to have a bathroom break, so it is not man, that is ridiculous but because not many are aware of this happening so frequently and in so many places, they can focus on one big one, delete reporting of the rest that follow non-stop, and say that man did it. Just know this ahead of time because when I try to write it on that site to say they are wrong I get deleted every time. They won’t post me. So there is some element out there that wants people to think man is using this geo program for war purposes against other nations. DON’T believe it, this is from God all of it not man. Proper knowledge will help you protect yourself. Things are very very bad, not even close to “recovery”……. Global warming is coming from rising magma. This is not man made either. Magma is made up of and releases carbon dioxide, sulfur and methane gases mostly. They all heat and they are all rising from the ground in to the air and wha la – global warming is here! Man can’t control the core of earth and thank God for that much! Stay safe and God Bless. Thanks.

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