10 New Insights about male NES based on results of 3- year survey during molting/breeding seasons

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1 10 New Insights about male NES based on results of 3- year survey during molting/breeding seasons Brittany Marnin BS, Gianna Milano BS and William J. Goodger DVM, PhD This summary of the 3 year male survey in the molting and breeding seasons could not have been completed without the assistance of previous interns Craig Brown, Kayla Wolfer, Shawn Hannah, Zach Hoffman,, and Melissa Voisinet. Their papers can be found in references at the end of this paper. 1. Updated method of male categorization for subadult and adult categories using pictures. After personal communication with Richard Condit (Smithsonian Research Institute) and Patrick Robinson (Ano Nuevo Island Reserve Director), categorization of male elephant seal sub-adult and adult categories were accomplished using Ano Nuevo s field classification system (Figure A). However, we decided to make some changes in the Ano Nuevo s classification system based on our experience especially during the counts in year 1. During the 2014 molting season we counted the SAM-1s (sub-adult male, category 1) and SAM-2s together because it was difficult to distinguish between these 2 categories. The Ano Nuevo system (Figure A) only recognizes SAM-2s and doesn t categorize SAM-1s. The methods of categorizations for the SAM-2 and SAM-1 were changed in the 2015 molting season because of what we viewed/learned on the beach concerning sub-adults. SAM-1s and SAM-2s were distinguished by nose development. SAM-1s are defined as having either no nose droop (beginning of a proboscis) or slight hanging nose droop that did not touch the sand (Figure B). SAM-2s had a nose droop that touched the sand (Figure C). In addition, when categorization was unclear, size was used to differentiate with SAM-1s being smaller than SAM-2s but certainly bigger than juveniles. Some of the early June counts had a larger total of unclassified seals because in some instances, we were unable to view the nose droop in relation to the sand. But as the SAM-1s started to leave the beaches in June, classification became much simpler and the unclassified count decreased. SAM-3s are categorized based on distinct morphological features including a nose droop almost like a SAM-4 but the chest shield is usually in the form of wrinkles on the underside of neck (Figure D). In addition, they are usually somewhat larger than the SAM-2s. More importantly, they can have a notch across the mid-portion of the nose that can be as small as a crease or as large as a small notch that might be seen on a SAM-4. The small notch may be more superficial than the similar notch seen on the nose of a SAM-4. SAM-4s are categorized as having a full-size nose and a chest shield that extends halfway up the neck, but not above the eyeline (Figure E). Adults are categorized as having a very big nose with a deep notch and a chest shield level with or above the eyeline (Figure F).

2 Figure A. Field Identification of Elephant Seals following Ano Nuevo s classification system (Obtained from Ano Nuevo Interpretive Guide for Docents, 2013). Figure B. SAM-1, classified as a slight nose drop but does not touch the sand. Figure C. SAM-2, classified as a slightly bigger nose droop than SAM-1, that touches the sand.

3 Figure D. SAM-3, classified as a bigger nose droop with a small notch and the beginning wrinkles of a chest shield. Figure E. SAM-4, classified as a full nose with a notch but a chest shield that does not reach eye level.

4 Figure F. Adult, classified as a full nose with notch and a chest shield that is eye level or above. 2. SAM-1 molt overlaps with juvenile and adult female molt. The molting season for juveniles (male and female) and adult females begins in early- April and lasts until about the end of May to early June. The molting season for males, SAM-2 or older, starts about mid-june and can last until mid-august to late-august. The survey found in the 2015 and 2016 molting season that the SAM-1s molt overlapped with the female and juvenile molt. Figure G s frequency histogram for 2015 indicated that on 6/15/2015 there were 1600 SAM-1s present on the 9 beaches surveyed that year. Then figure H s frequency histogram indicates that on 6/6/2016 there were 1200 SAM-1s present on the 9 beaches surveyed that year. In 2015, SAM-1 numbers had decreased by almost 90% by the end of June and in 2016 had decreased by almost 70% by the end of June (figure G, H). This timeframe is during a time when other subadults and adult males have not reached their peak molting numbers yet. In fact, at the 6/6/2016 survey, there were between females that still had not left for their long migration. There have always been some SAM-1s on the beach during the molting season for juveniles and adult females. However, the early June counts indicate we may need to confirm this insight that SAM-1 molting may overlap with females and juveniles. To do this we may need to survey SAM-1 numbers during May. This survey would inform us about the number of SAM-1s leading up to the June numbers.

5 Figure G. Frequency histogram for each of the classes of male elephant seals in Figure H. Frequency histogram for each of the classes of male elephant seals in SAM-3 category as a special case using updated features to identify seals. When we added up the male counts during the 2014 molting season we found that there were more SAM-4s than SAM-3s which is unlikely as SAM-3s become SAM-4s (Figure I). Thus, in the 2015 molting season we were looking for a better way to categorize SAM-3s and SAM-4s. In addition to nose droop and chest shield mentioned in Insight 1, we discovered a helpful method to differentiate SAM-3s from SAM-4s by noting the beginning of a notch in the midportion of the nose. In the previous year (2014), these somewhat smaller seals may have been called SAM-2s. This beginning of a notch was like a small crease across the nose where the notch would be in SAM-4s and adults (Figure J).

6 Figure I. Number of individuals within each age class throughout the 2014 molting season. Figure J. SAM-3, has the beginning of a notch shown by a small crease. The change in categorization rules for SAM-3s in 2014 compared to 2015 made a noticeable difference in the results. The 2015 categorization used the notch as described above as additional criteria along with size. This helped to more reliably distinguish the SAM-3s from SAM-2s and assisted our ability to obtain a more reliable count of SAM-3s when compared to SAM-4s. This resulted in the number of SAM-3s being larger than that of the SAM-4s at every count both during 2015 and 2016 molting seasons (Figure K, Figure L).

7 Figure K. Age categories across the molting season, excluding SAM-1s for the 2015 molting season. Figure L. Age categories of male elephant seals across the molting season, excluding SAM-1s for 2016 molting season. 4. SAM-2 haul out pattern for the molting season is similar to adults except after the middle of July it drops off rapidly.. SAM-2s seem to follow a molting season haul out pattern similar to that of the adult males. However, as seen in Figure K and L above, under Insight 3, in both 2015 and 2016 after mid-july, the SAM-2 count has a large decline. In adult males, the population count does not drop significantly until late August. The SAM-2 count may decline abruptly because of being intimidated by the adults, after all it is their first-year molting with the adults. The SAM-3s and 4s in the past years have already confronted the adults, which may be the reason their haul out and return to the ocean is more consistent over time.

8 5. Adults haul out over a longer period of time compared to the SAMs Adult males have much higher numbers on the beaches for a longer period of time compared to the SAMs. When females begin to leave the beach after breeding season, males stay an average of 15 days longer (Stewart 1994). As seen above in Figure K and L, the adult males begin to arrive on the beach during molting season at the beginning of June but stay through the end of August with higher numbers than all the others. These males lost varying amounts of weight, between lbs, during the 3-month fast during breeding season. They come back onto the beaches at different times to molt because some may need more time in Alaska to feed while others may not. We can speculate that those who lost less weight, may come back sooner than those that lose more during the breeding season, thus allowing a more extended range of haul out time. 6. There is a difference in counts of the number of adult males between the breeding and molting seasons in 2015 and By looking at table 1 one will notice the large difference in counts of the number of adult male elephant seals between seasons. Using only 2 full years for this analysis (breeding and molting), in both 2015 and 2016, the breeding season had many more adult male elephant seals than the molting season did. We used the breeding season as our base population. Because of this, we could only use full years of 2015 and Our observations did not include having both breeding and molting season data collected from 2014 and For example, in 2014, we did not collect breeding season data, and in 2017, molting season data. For this insight, the next question is, did these results occur by chance alone. To answer this question we applied some statistics and found out the probability was low(.0060) that the difference between the numbers of adult males in the 2 seasons occurred by chance alone. The next question for us as researchers would be to try to hypothesize why this may have occurred. First, there could be fewer adult males in the colony if mortality exceeds recruitment of SAM-4s during their post breeding foraging trip. Second, some adult male elephant seals in the Piedras Blancas colony may be molting elsewhere, possibly at rookeries up north such as Vancouver Island (British Columbia), Cape Arago, and Cape St. George (Oregon) (Stewart et. al., 1994). These 3 rookeries only have elephant seals during the molting season and none during the breeding season. The only citation that provides some insight is from B. Le Boeuf, In his findings, he noted that sexually mature males molt at the same colony location where they breed. In order to verify these results, a more aggressive tagging program would need to be used to follow the migratory patterns of the adult males in the breeding/molting seasons.

9 Number Season Count breed breed breed molt molt molt breed breed breed molt molt molt 183 Table 1. Table of counts for breeding and molting seasons The availability of adult males to breed the increasing number of adult females remained constant. As the number of females increase on the Piedras Blancas beaches, we inspected the survey data to assess whether there are enough adult males to continue to service the females on the beach. The number of adult males in the breeding season has been maintained. Over the last 3 years the three-year average for adult males was 237 with only small variation from year to year (Figure M). Figure M. Histogram of the number of average breeding males for each breeding season

10 8. The range of adult male beach counts Throughout the 3 years of surveys, there were 5 beaches (Arroyo del Corral, Piedras Blancas, Surfers Beach, VP3 South, VP3 Cove) that had average counts which differed by 5 animals or fewer and the other 4 beaches (VP1, VP2, VP3 North, and VP4-Middle) averaged counts that differed by 8-10 seals (Figure N). The counts that had greater differences in seal numbers had bigger and more difficult beaches where counting was much harder. For example, Vista Point 2 (VP2) has a very wide range that requires driving or walking to separate places and also has a high chance for the seals to be in the water since there is little beach area. This made it counting more difficult than at other beaches that did not have as many obstacles. Nevertheless, every beach count in the past three years of surveys did not exceed a difference of more than ten animals Adult Male Counts During Breeding Number of Individuals Arroyo del Corral Piedras Blancas Surfers Beach VP1 VP2 VP3 North VP3 South VP3 Cove VP4 to Middle Location Figure N. Adult male elephant seal counts during breeding season at each of the 9 different beaches between Adult males do not leave until the last female has left during breeding season There were 3 counts conducted during each breeding season; at the end of January, the middle of February, and the end of February. The histogram (Figure P) includes only the last two counts which cover the mating period in order to ensure all adult male elephant seals were on the beach at the time of the survey. The majority of female elephant seals come onto the beaches to give birth between the middle of December and the end of January. Therefore the last two counts

11 are used with confidence that all adult male seals should be on the beach during those times. Between the second and third counts, the majority of females that arrived in December/January have left the beach and returned to the ocean to forage, but the adult male counts indicate that most adult males remain on the beach each year ( ) at the end of February (Figure O) Adult Male Breeding Season Counts Number of Individuals nd Count 3rd Count Counts Figure O. Average breeding counts for the last three surveys for the breeding seasons. 10. The similar male elephant seal counts by each beach over the 3-year survey period faced very challenging survey conditions which could have resulted in errors. When researching, there are many challenges that can affect or even skew the data that is collected. To begin, there were many interns assisting in the three-year survey data collection, which could result in inconsistent findings. To offset the fact that there were many different people on this project, each member of the group had to have a count within 5% of the other members. If that was not the case, everyone needed to start over and count until the counts were each within 5% of one another. Once the counts were within 5% the final numbers were averaged. The average value was used as the data point for further analysis. Other possible

12 challenging conditions that could potentially result in errors in the count include as follows. Below are two figures (Figure P and Figure Q) that can give a better visual of these challenges. The animals were in and out of the water making it very hard to define which animals were already counted and which were not. Weather and visibility is a major factor on the northern coastline of Highway 1 and majority of days are cloudy and foggy making it hard to see very far. There is also only a certain distance we walk as researchers so the farther away the animal in less-than-ideal conditions, the harder the visibility. The animals could also be hidden in the dunes that are on many of these sandy beaches with uneven terrain that may make it difficult to get around the dunes or even to the beach in the first place. This also makes it difficult to even know there is an animal in the dune because they are completely hidden. The animals tend to line up along the beach, side by side but are facing away, toward the horizon. Much of these challenges lead us to Unclassify animals which are those that we are unable to tell whether they are subadult or adult, male or female, for various reasons; underwater, under each other, facing away, etc. An unclassified animal prevents us from categorizing an animal and creating incorrect data. There are more unclassifieds counted during molting season because they are categorized as Subadults 1-4 and adults rather than the subadults and adults category during breeding season. Figure P. This image of Vista Point 2 (VP2), shows a clear day in San Simeon but with limited beach, rocks in the water, and limited visibility of distance with only binoculars to count the seals. Figure Q. An example of animals that may be considered unclassified when laying on top of one another, limiting the researcher s ability to see their noses and chest shields

13 References Stewart, B. S., Yochem, P. K., Huber, H. R., DeLong, R. L., Jameson, R. J., Sydeman, W. J., Allen, S. G., & Le Boeuf, B. (1994). History and present status of the northern elephant seal population. Elephant seals: population ecology, behavior, and physiology, Le Boeuf, B, Ainley, D., and Lewis, T. (1974). Elephant seals on the Farallones:Population Structure of an Incipient Breeding Colony. Journal of Mammalogy 55, no.2. pp Brown, Craig and William J. Goodger. (2014). Population Survey of Male Northern Elephant Seals at the Piedras Blancas Rookery during the Molting Season. Friends of the Elephant Seals. Wolfer, Kayla, Shawn Hannah and William J. Goodger. (2015). Population Survey of Male Northern Elephant Seals at the Piedras Blancas Rookery during the Breeding Season. Friends of the Elephant Seals. Hoffman, Zach and William J. Goodger. (2015). Population Survey of Male Northern Elephant Seals at Piedras Blancas Rookery during the Molting Season: Year Two. Friends of the Elephant Seals. Voisinet, Melissa, Gulce Ozturk, and William J. Goodger. (2016). Population Survey of Male Adult and Subadult NES at the Piedras Blancas Rookery during the 2016 Breeding Season. Friends of the Elephant Seals.